Abstract:
An electrical switch for connecting and breaking a circuit including a connecting and breaking mechanism for connecting and breaking the circuit provided with at least a set of movable contacts and stationary contacts; a electromagnetism drive mechanism for controlling the contacts to be actuated so as to realize closed circuit; a housing for accommodating the movable contact and stationary contact; an arc-extinguishing mechanism disposed in the housing and corresponded to the movable and stationary contact; a case connected to a base for accommodating the electromagnetism drive mechanism; a bedplate associated with the case; and a holding mechanism disposed on the bedplate for holding the contacts to connect the circuit, the electromagnetic holding mechanism is electromagnetic and has a set of electromagnetic attracting mechanism in which the movable iron core is made to be a pothook or a baffle mechanism, the movable iron core is attracted so that the pothook or baffle keeps the switch closed by means of hitching or ramming the movable bolt when the electromagnetic attracting mechanism is powered on. The electrical switch has a structure in which it has a breakaway mechanism using winding, in which the remanence being small and the feedback force being large and the action of the limiting current being rapid, it can break the large short current as air switch.

Description:
This application claims the benefit of PCT Application No. PCT/CN2004/000563 filed May 28, 2004 which further claims the benefit of Chinese Patent Application No. 03140553.3 filed May 29, 2003. The entire disclosures of PCT Application No. PCT/CN2004/000563 and Chinese Patent Application No. 03140553.3 (Publication No. 1553464A) are incorporated by reference as part of the specification of this application. 
     FIELD OF THE INVENTION 
     The present invention relates to an apparatus for connecting and breaking a circuit between a load and a power supply, which can be called an electrical switch and may be one single phase or three-phase switch. The present invention mainly introduces one three-phase electrical switch, whose load is a three-phase AC motor. 
     DESCRIPTION OF THE RELATED ART 
     In 1983, an Integral 32 combination electrical appliance was put on the market by Telemecanique (TE) Company in France, it represents the world&#39;s level today,  FIG. 45  is view showing the structure of its switch portion, in which the connection and break of the switch are controlled by an attracting coil WI. A current limiting mechanism comprises a current limiter W 3 , a percussion bar B 5 , and a striking bar  65 . Z 1  denotes a tension spring, Z 2  denotes a spring, the force of the tension spring Z 1  is greater than that of Z 2 . When the attracting coil W 1  is powered on, a connection board  20  rises the spring Z 2  so as to make the contact of the switch be closed, when the attracting coil W 1  is powered off, the tension spring Z 1  draws and presses Z 2  so as to make the contact be disconnected. When an over-current flows through the switch, the current limiter W 3  attracts percussion bar B 5  to make the striking bar  65  strike tension spring Z 1 , so that the movable contact and the stationary contact can be disconnected at a rapid speed. The bigger the current is, the faster the disconnection speed is. TE Company has been granted two Chinese Patents No. 89108203 and No. 89108547, respectively. 
     Shanghai Electrical Power Science and Research Institute has developed the same product as TE Company, and has been granted Chinese Patent No. 95227387. 
     The present inventor disassembled and analyzed the product manufactured by TE Company, and found out that it was too complicated to describe, at the same time, the product always keeps in the closed state as a contactor, and the power consumption is high. In contrast, the present switch is simpler, and the power consumption is lower, the present inventor has produced the sample. 
     German Moeller Company has also produced a compact motor starter, it has only changed the conventional air switch, contactor and thermorelay into the inserted switch so that the entire system has a small size. 
     SUMMARY OF THE INVENTION 
     To solve the problem described above, in accordance with one aspect of the present invention, there is provided an electrical switch for connecting and breaking the circuit, said electrical switch centralizes all the functions of the breaker, the contactor and the protective relay, it serves to connect, break and protect the circuit, not only to be operated frequently as the contactor, but also to break the larger short circuit current as the air switch. The switch has a small size, and a compact structure, in addition, it can save the electric energy. 
     In order to achieve the above and other objects, the present invention provides an electrical switch for connecting and breaking a circuit, including: a connecting and breaking mechanism for connecting and breaking the circuit provided with at least a set of movable contacts and stationary contacts; a electromagnetism drive mechanism for controlling the contacts to be actuated so as to realize closed circuit; a housing for accommodating the movable contact and stationary contacts; an arc-extinguishing mechanism disposed in the housing and corresponded to the movable and stationary contact; a case connected to a base for accommodating the electromagnetism drive mechanism; a bedplate associated with the case; and a holding mechanism disposed on the bedplate for holding the contacts to connect the circuit after the contacts are connected, the holding mechanism is electromagnetic and has a set of electromagnetic attracting mechanism in which the movable iron core is made to be a pothook or a baffle mechanism, the movable iron core is attracted so that the pothook or baffle keeps the switch closed by means of hitching or ramming the movable bolt when the electromagnetic attracting mechanism is powered on. 
     Said electrical switch further includes a coil, a conducting magnet plate, a bracket, and a tension spring; the pothook or baffle intersects the top end of the conducting magnet plate, and has an inclined plane at a position where is contacted with the movable bolt so as to disconnect the movable bolt. 
     In another aspect of the present application, there is provided an electrical switch for connecting and breaking the circuit, including: a connecting and breaking mechanism for connecting and breaking the circuit provided with at least a set of movable contacts and stationary contacts; a electromagnetism drive mechanism for controlling the contacts to be actuated so as to realize closed circuit; a house for accommodating the movable contact and stationary contact; an arc- extinguishing mechanism disposed in the housing and corresponded to the movable and stationary contacts; a case connected to a base for accommodating the electromagnetism drive mechanism; a bedplate associated with the case; and a holding mechanism, which is an elasticity type, disposed on the bedplate for holding the contacts to connect the circuit after the contacts are connected; a pothook or baffle of said holding mechanism keeps the switch closed by hitching or ramming the movable bolt by means of elasticity, said holding mechanism further includes a spring, a stop button, and a reset button, said pothook or baffle abuts against the movable bolt. 
     Said electrical switch further includes a current limiting mechanism disposed on the bedplate for detecting and limiting over-current, said over-current mechanism includes a set of electromagnet corresponding to each of phase circuit and a set of connecting rod mechanism connected with thereof, said connecting rod mechanism has a rod which can rapidly thrust aside the movable iron core of the holding mechanism when the over-current occurs, and further includes a spring, a pushing plate, a pushing bar and a bracket. 
     Said electrical switch further includes a selection switch mechanism disposed on the Bedplate, said selection switch mechanism comprises a set of movable and stationary slide slices in which the movable slide slice moves along with the turnbutton bar, said selection switch may move both in the rotary direction and in the vertical direction to control the operating state of the switch. 
     Said electrical switch further includes a selection switch mechanism disposed on the bedplate, said selection switch mechanism comprises two sets of micro buttons and a mechanism for connecting and breaking the circuit comprised of a turnbutton, a turnbutton bar, a movable slide slices and a stationary slide slices. 
     Said electrical switch further includes a comprehensive protector, said comprehensive protector has a thermal element action means corresponding to each phase circuit, the thermal element action means can disconnect the said switch when the over-current occurs and further has a phase failure detecting mechanism corresponding to the main circuit which can disconnect said switch in detecting the phase failure. 
     Said switch is a combination type one, it comprises a switch portion and a protection portion, which will be described with reference to  FIGS. 10 ,  11  and  17 , it may be a selective type or a nonselective type depending on whether there is a selection switch, the selective type employs the circuit shown as  FIG. 1 , while the nonselective type employs the circuit shown as  FIG. 2  or  FIG. 3 . 
     Said switch portion includes a contact and closing mechanism, a holding mechanism using a pothook or a baffle, a limiting current mechanism, a connecting and supporting mechanism and a selection switch mechanism. 
     Said protection portion includes an overload protection mechanism, an over-current protection mechanism, a phase failure protection mechanism and a reset mechanism. 
     Now, the operation of the switch will be described in details below. 
     When the attracting coil W 1  is powered on, the movable and stationary iron cores and the contacts are closed to make the holding coil W 2  be electrified so as to attract the pothook E 1 , which can hook or repel the movable bolt  19 . At this time, though the coil W 1  is powered off, the closing state is maintained by the coil W 2  attracting the pothook E 1 , when it needs to disconnect the switch, the coil W 2  is powered off, the pothook E 1  rapidly breaks away the movable bolt  19  by a tensile force of the tension spring Z 1  and a component force of the spring Z 2 . 
     When the pothook E 1  breaks away the movable bolt  19 , the switch trips to make the movable iron core and the movable contacted and the stationary iron core and the stationary contact are rapidly separated from each other due to the spring Z 2 . 
     When the over-current occurs in the switch, the selection switch ejects immediately to turn off the switch K 2 , K 3  and SA, and strikes the pothook E 1  to disconnect from the hook so as to turn off the switch. The switch can be turned on only when the reset button of the selection switch is pressed. 
     When the overload or over-current occurs in the switch, the protection mechanism breaks away the contact K 1  to make the coil W 2  be powered off and make the switch trip. The switch can be turned on again only when the protection mechanism is reset. 
     Generally, the air switch is manually operated, its disconnection capacity is high (as an example of the switch 32 A-400V, it has a disconnection capacity of 50000 A as 1562 times as its rated current), but its lifespan is short, and it is difficult to start frequently. In contrast, since the contactor is electrically operated, its lifespan is long, it can be started frequently, but it only has a disconnection capacity as 10 times as its rated current. 
     The reason why the disconnection capacity of the air switch is higher than that of the contactor is mainly that its disconnection speed is faster. The present inventor thinks that the reason why the disconnection speed of the contactor is slower has two factors: the one is that the contactor is heavier than the air switch in weight, the other one is mainly that there is magnetic remanence in the contactor when it is powered off instantly. 
     At present, it is necessary to have the following functions in the electrical machine controlling system, that is, a overload protection, a short-circuit protection, a separation control, a rapid and easy control. These functions are generally carried out through the air switch, the contactor and the overload relay. The switch has all above functions, when it is turned on, the coil W 1  is turned off immediately, and the magnetic remanence is small. 
     Compared with said product, the switch has many following advantages: 1) the switch has a small size, and a simple structure, it can be near-controlled, be stopped and be remote-controlled by the selection switch, its operation is convenient and flexible; 2) the holding coil has a capacity less 5% than that of the attracting coil, and it saves energy; 3) since the switch employs the pothook structure, the pressure of its contact keeps stable, it is different from the conventional attracting coil which is often affected by the voltage variation of the power network which fluctuate in a sine wave forms, so the contact can be easily damaged; 4) the over-current action of the switch is short, and the response speed is rapid. 
     In particular, the switch has a good practical effect, though it is said that the product manufactured by TE has a disconnection capacity of 50 KA, it is infrequency in practice. For example, the maximum short circuit current in the transformer of 560 KVA is only 16.7 KA, and that of the transformer of 1800 KVA is only 48 KA. In practice, the switch may usually be partial short, sometimes the short circuit current is several times more than the rated current. It is impossible to make the striking bar of the product manufactured by TE be actuated, or make the breaker of the starter in the compact motor be actuated, in contrast, it can make the loop voltage on the attracting coil drop, they will be disconnected because the attracting force is smaller than the feedback force. Since some certain attracting forces also produce in the coil, the disconnection speed is slow, the contact tends to be turned out due to the pulling arc. Sometimes, though the load is not shorted, the voltage on the power network is low, said contact of the switch also be easily damaged. 
     Since the present switch employs the tripping disconnection mechanism, its disconnection speed is mainly affected by the feedback force, even if the trip occurs in the holding coil due to the dropping voltage, the disconnection speed keeps constant, accordingly, the aforesaid problems do exist at all, therefore, the present switch is more practical and more reliable. 
     Since the present switch has a structure in which it has a breakaway mechanism using winding, in which the magnetic remanence being so small to be negligent, meanwhile, its feedback force may be designed to be large. The action of the limiting current mechanism may be rapid. Therefore, it can break the large short circuit current as an air switch while it saves the energy. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will become clearer from the following description of the specific preferred embodiments with reference to the attached drawings, in which: 
         FIG. 1  is a view showing the circuit diagram of a selective electrical switch; 
         FIG. 2  is a view showing the circuit diagram of a nonselective electrical switch; 
         FIG. 3  is a view showing the circuit diagram of a resilience-holding electrical switch with electrical actuation; 
         FIG. 4(   a ) is a view schematically showing a state after the selective switch is closed; 
         FIG. 4(   b ) is a view schematically showing a state after the selective switch is disconnected; 
         FIG. 4(   c ) is a view showing the action path of the selective switch; 
         FIG. 5  is a view schematically showing the structure of the movable slide slice shown in  FIG. 4(   a ) and  FIG. 4(   b ); 
         FIG. 6  is a view schematically showing the structure of the fixed slide slice shown in  FIG. 4(   a ) and  FIG. 4(   b ); 
         FIG. 7  is a view schematically showing the structure of the turn-button bar shown in  FIG. 4(   a ) and  FIG. 4(   b ); 
         FIG. 8  is a view schematically showing the structure of the elastic baffle shown in  FIG. 4(   a ) and  FIG. 4(   b ); 
         FIG. 9  is a view schematically showing the operation position of the selective switch, in which  FIG. 9(   a ) is a state of being remote-controlled,  FIG. 9(   b ) is a state of being stopped,  FIG. 9(   c ) is a state of being directly connected; 
         FIG. 10  is a top view showing the structure of the vertical bolt switch; 
         FIG. 11  is a section cross view showing the structure of the pothook switch; 
         FIG. 12  is a section cross view showing the structure of the baffle switch; 
         FIG. 13  is a view schematically showing the structure of the movable bolt shown in  FIG. 11  and  FIG. 12 ; 
         FIG. 14  is a view schematically showing the structure of the holding mechanism shown in  FIG. 11 ; 
         FIG. 15  is a view schematically showing the structure of the pothook show in  FIG. 11 ; 
         FIG. 16  is a view schematically showing the structure of the limiting current mechanism shown in  FIG. 11  and  FIG. 12 ; 
         FIG. 17  is a section cross view showing the structure of the electrical switch implemented according to the present invention; 
         FIG. 18  is a view schematically showing the structure of the switch in which the contact is positioned on its top end; 
         FIG. 18  ( a ) is a view showing the circuit diagram of the structure of the electronic tripper; 
         FIG. 19  is a view schematically showing the structure of the nonselective switch in which the contact is positioned on its top end; 
         FIG. 20  is a top view and cross section view showing the structure of the side hook type electrical switch, respectively; 
         FIG. 21  is a view schematically showing the structure of the single contact side hook type electrical switch; 
         FIG. 22  is a cross section view showing the structure of the side hook type electrical switch shown in  FIG. 20 ; 
         FIG. 23  is a view schematically showing the structure of the holding mechanism of the side hook type electrical switch shown in  FIG. 20  and  FIG. 22 ; 
         FIG. 24  is a view schematically showing the structure of one current limiter shown as  FIG. 20 ; 
         FIG. 25  is a view schematically showing the structure of another current limiter shown as  FIG. 20 ; 
         FIG. 26  is a view schematically showing the structure of the resilience-holding mechanical switch with electrical actuation; 
         FIG. 27  is a view schematically showing the pothook coupled with the movable bolt in the resilience-holding switch; 
         FIG. 28  is a view showing the shape of the connecting shaft in the switch shown as  FIG. 26 ; 
         FIG. 29  is a view schematically showing the structure of one mechanical-electrical protector; 
         FIG. 30  is a view schematically showing the structure of another one mechanical-electrical protector; 
         FIG. 31  is a view schematically showing the structure of the contact of the mechanical-electrical protector shown in  FIG. 30 ; 
         FIG. 32  is a view showing a state after the over-current occurs in the protector shown in  FIG. 30 ; 
         FIG. 33  is a view showing the phase failure control circuit of the protector shown in  FIG. 29 ; 
         FIG. 34  is a view schematically showing the structure of the connecting shaft and compensation slice in the protector shown in  FIG. 30 ; 
         FIG. 35  is a view schematically showing the element in assembly of the protector shown in  FIG. 30 ; 
         FIG. 36  is a view schematically showing a state after the tripper shown in  FIG. 30  is tripped; 
         FIG. 37  is a view schematically showing the structure of the overload bar in the protector shown in  FIG. 30 ; 
         FIG. 38  is a view schematically showing the structure of the bracket in the protector shown in  FIG. 30 ; 
         FIG. 39  is a view schematically showing the structure of the movable arc contact; 
         FIG. 40  is a view schematically showing the structure of the V-shaped contact; 
         FIG. 41  is a view schematically showing the structure of the switch with a protective fuse; 
         FIG. 42  is a view schematically showing the structure of one switch in which the movable iron core has separated from the movable bolt; 
         FIG. 43  is a view schematically showing the structure of another switch in which the movable iron core has separated from the movable bolt; 
         FIG. 44  is a view schematically showing the structure of the impacting switch; 
         FIG. 45  is a principle diagram showing the structure of the switch produced by TE Company; 
         FIG. 46  is a view schematically showing a state in which the nonselective switch indicates the over-current and breaks away, the reset mechanism resets; 
         FIG. 47  is a view schematically showing a state in which the nonselective switch indicates the over-current and breaks away, the reset mechanism feedbacks; 
         FIG. 48  is a front view showing the switch according to one preferred embodiment of the present invention, on which the assistant contact is disposed; 
         FIG. 49  is a top view showing the switch shown in  FIG. 48 , in which it has the assistant contact and the slide way; 
         FIG. 50  is a cross section view showing the structure of the switch shown in  FIG. 48 ; 
         FIG. 51  is a view showing the electrical circuit of the switch shown in  FIG. 48 ; 
         FIG. 52  is a side view showing the switch according to one preferred embodiment of the present invention; 
         FIG. 53  is a view schematically showing the position of the turnbutton when the switch shown in  FIG. 52  is turned on; 
         FIG. 54  is a view schematically showing the position of the turnbutton when the switch shown in  FIG. 52  is turned off; 
         FIG. 55  is a view schematically showing the connection and break of the circuit in the switch shown in  FIG. 52 ; 
         FIG. 56  is a view schematically showing the structure of one current limiter mechanism; 
         FIG. 57  is a view schematically showing the structure of the attracting iron in the switch shown in  FIGS. 48 ,  49 ,  50  and  52 ; 
         FIG. 58  is a view schematically showing the structure of the pushing bar in the switch shown in  FIGS. 48 ,  49 ,  50  and  52 ; 
         FIG. 59  is a view schematically showing the structure of the insulating bracket. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The electrical switch according to the present invention will hereinafter be described in details by reference to the attached drawings. 
     1. The Electrical Circuit of the Electrical Switch 
       FIG. 1  is a circuit diagram shows one of the features of the present invention, in which after the switch is attracted and closed by means of the contact inside the switch, the circuit can assure the attracting coil to be powered off immediately, while can keep the holding coil be powered on so as to be on a self-protected state, if the switch is selected to be operated by the remote button, it can reduce one self-protection wire compared with the contactor, therefore, it is simple. 
       FIG. 1  shows one preferred circuit of the selective electrical switch, in which the elements and the circuit in the switch are disposed in the large broken line block, A, B, C are input source terminals respectively, a, b, c are input load terminals respectively, x 1 , x 11 , x 2 , x 22  are output assistant contact terminals respectively, L, N are control source terminals, W 1 , W 2  are control terminals, K is the main contact and the assistant contact of the switch, W 1  represents attracting coil, W 3  represents over-current control mechanism, there is a comprehensive protector in the Z block, some comprehensive protectors contain the over-current control mechanism W 3 , there is a holding coil mechanism in the block of the control terminal W 2 . It includes a holding coil W 2 , a rectification element, a continuation current element and a display element etc, which are all assembled on the element board EJ, there is a selective switch in h block. The attracting coil in the circuit also uses a DC source. The other kind of switch may employ the circuit shown in  FIG. 2  or  FIG. 3 . 
     2. The Operation of the Selective Switch and the Elective Switch 
     The electrical switch includes the selective switch and the nonselective switch, in which the operation of the selective switch depends on the selection switch. 
     The selective switch is one of the features of the present invention, it has two functions of selecting the operation state and breaking the electrical circuit, and has a rotary action and a vertical action. 
       FIG. 4(   a ) and  FIG. 4(   b ) are views schematically showing a structure of the selective switch, portion  1   h  in  FIG. 1  is a block diagram showing its circuit, it has three switch K 2 , K 3 , SA, also includes a turnbutton  2  and turnbutton bar  26 . There is a bowl-shaped ring  27  in the turnbutton bar  26  in which its top end is flat, its bottom end is round, as shown  FIG. 7 . Z 4 , Z 5  represent springs, the reference number  28  represents a branch pipe, the reference number  29  represents a movable slide slice, in which an elongated hole matched with the turnbutton bar  26 , a rim and a contact area are sequentially arranged on the middle portion of the movable slide slice  29 , and the movable contacts dl, d 2  are disposed on the movable slide slice  29 . As shown  FIG. 5 , the buttons on two sides of the movable slide slice  29  are to limit the rotary range. The reference number  30  represents the fixed slide slice, in which a hole passing through ring  27 , a cog circle, and a contact area are sequentially arranged on the middle portion of the fixed slide slice  30 , and the fixed contacts f 1 , f 2 , f 3  and f 4  are disposed on the fixed slide slice  30 , the buttons on its two sides are to fix these above elements, as shown  FIG. 6 . There are grooves among these contacts to increase the creepage distance. The rims of the movable and fixed slide slices fit with each other to adjust the gear. The reference number  32  represents a pushing block made of elastic material, as shown  FIG. 8 . 
     While the selective switch being assembled, the fixed slide slice  30 , the spring Z 4  and the pushing shield  32 , whose front ends are blocked by the side of the turnbutton  26 , their back ends are supported by the pad  33  which is riveted on the turnbutton bar  26 , are muff-coupled in serial on the turnbutton bar  26 . The back end of the spring Z 4  may be directly blocked by the bracket  88 . The fixed slide slice  30  may be disposed on the back end of the spring Z 4 , also may be directly blocked by the bracket  88 . The fixed slide slice  30  can move in the direction of the elastic force of the spring Z 4 , the fixed slide slice  30  and the pushing block  32  can rotate along with the turnbutton bar  26 . Then, the turnbutton bar  26  passes through the fixed slide slice  30 , and is fixed on the bracket  88  by the fixed member  31  and the branch pipe  28 . After being sleeved on the spring Z 5 , the turnbutton bar  26  is fixed on the bedplate  68  of the switch, as shown  FIG. 4(   a ) and  4 ( b ). 
     The selective switch has three-position type and four-position type, whose operation path is shown as  FIG. 4(   c ), it can rotate in the direction shown as the arrow in the figure, and select the operation state, the operation state of each block position follows as: 
     D 1  remote control: when the selective switch directs to this position, K 2 , K 3  are turned on, SA is turned off. At this time, the switch is only remote controlled, turned on or stopped. 
     D 2  stop: when the selective switch directs to this position, K 2 , K 3  and SA are all turned off, the power supply is controlled by the switch, and the switch is powered off. 
     D 3  direct connection: when the selective switch directs to this position, K 2  and SA are turned on, the switch is powered on. 
     D 4  direct lock: only the four-position type selective switch has a direct connection locking position and the pushing block  32 . When the selective switch turns from the direct connection position to the direct connection locking position, K 2 , K 3  and SA are all turned off, a pothook E 1  is opposed against the pushing block  32  to lock the movable bolt  19  so as to make the switch closed such that the pushing block can maintain in the holding state. 
     The connecting and breaking state of the three-position type selective switch in every blocking position is shown as  FIG. 9 , in which (a) indicates the remote control, (b) indicates stop, (c) indicates the direct connection. 
     The nonselective electrical switch does not have a selective switch, and it employs the circuit shown as  FIG. 2 . 
     3. The Structure of the Switch Portion of the Electrical Switch 
     (1) The Structure of the Vertical Bolt Electrical Switch 
       FIG. 10  is a top view showing the structure of the vertical bolt switch, including the switch portion and the comprehensive protection portion. The switch portion has a current limiter.  FIG. 11  is a section cross view showing the closed state of the switch maintained by the pothook mechanism holding switch;  FIG. 12  is a section cross view showing the closed state of the switch maintained by the baffle mechanism holding switch, all of which are applied to the circuit shown as  FIG. 1 , which will be explained respectively as below. 
     a. The Contact and Closing Mechanism 
     The mechanism includes a attracting coil W 1 , a stationary iron core  15 , a stationary contact  17 , a movable contact  14 , a guiding arc slice  89  and a arc extinguisher  6 , in which the contact mechanism uses a repulsion force type. The movable iron core  16  and the movable bolt  19  are connected together with the connection board  20 , the insulting connection frame  21  and the movable contact  14 . 
     While the coil W 1  is powered on, the movable iron core  16  is attracted to make the movable contact  14 , the movable bolt  19 , the connection board  20  and the insulting connection frame  21  move along the direction shown as F 1 , therefore, the movable iron core  16  and the movable contact  14  close respectively the stationary iron core and the stationary contact. In the figure, the reference number  93  represents a rubber pad for absorbing shock and reducing the remanence. 
     b. The Holding Mechanism 
     The holding mechanism is one of the features of the present invention, it employs a pothook or baffle E 1  to make the switch closed by means of hitching or ramming the movable bolt  19 . The holding mechanism may be placed in the different positions corresponding to the movable bolt  19 , and it has several various structures such as an electromagnetic holding mechanism, an elastic holding mechanism and a pushing block holding mechanism etc according to the different holding modes. W 1 , W 2 , and W 3  represent the electromagnetic irons including the iron core and the coil, all of which are indicated by the coil or W 1 , W 2  and W 3  throughout the accompanying drawings. 
     The electromagnetic holding mechanism includes W 2  and the relevant elements inside the shield W 2  in the  FIG. 1 , comprising the pothook or baffle E 1 , the movable bolt  19 , a magnet conducting plate  23 , a bracket  69  and a tension spring Z 1 , as shown  FIG. 14 .  FIG. 15  is a view schematically showing the structure of the pothook E 1 , and also showing the structure of the intersection of the top end of the magnet conducting plate  23  and the pothook E 1 , in which the surface X on the pothook E 1  is an inclined plane, that is to say, an included angle is formed between the surface x and the direction F 1 , it is advantageous to make the pothook E 1  disconnect with the movable bolt  19 . 
     When the coil W 2  is powered on, the pothook E 1  is attracted to hitch or ram the movable bolt  19  so as to make the switch closed. 
     The movable bolt  19  is one of the features of the present invention, and is one part of the holding mechanism, it may be attached to the iron core end on which the iron core intersect with the contact vertically, as shown  FIGS. 11 and 17 , also may be attached to the contact end as shown  FIG. 43 , further may be attached to the iron core end on which the iron core is parallel with the contact as shown  FIGS. 20 and 21 , or be fixed on the other position where it can connect the switch,  FIG. 13  is a view schematically showing the structure of the movable bolt  19 . 
     c. The Current Limiting Mechanism and the Over-Current Trip of the Switch 
     The current limiting mechanism is one of the features of the present invention, it is connected in serial in the main loop circuit. Since its action is direct and easy, and the intrinsic time is very short, the capacity of breaking the expected short circuit current is high. 
     The limiting current mechanism is comprised of a coil W 3 , a tension spring Z 3 , a pushing plate  86 , a pushing bar  87  and a bracket  90 , as shown  FIG. 16 . In the figure, the reference number  91  represents the coil core, the reference number  92  represents the coil insulting case, in which the coil wire is wound outside the case. 
     The coil W 3  is connected in serial in the main loop circuit as a current limiting mechanism, when an over-current occurs in the switch (the over-current is preferably as 12 to 16 times as that of its rated current), the pushing plate  86  is attracted to push the pushing bar  87  to move along the direction F 2 , the pushing bar  87  pushes the pothook E 1  to make it disconnect with the movable bolt  19 , such that the switch is tripped off. At this time, the pushing bar  87  disconnects with the duplex ring  27  on the other pushing block of the switch, the spring Z 5  can make the turnbutton  2  and the elements connected in serial on the duplex ring  27  jump up along the direction F 3  until the bracket  88  can block the pad  33 . At this time, the movable contacts d 1  and d 2  separate from the stationary contacts f 1 , f 2 , f 3  and f 4 , thereby turning off the power supply of the switch, meanwhile, as shown  4 ( b ), it is clear for at a glance that the turnbutton  2  is apparently high. 
     If it needs to reset, the turnbutton  2  is pressed. At this time, the duplex ring  27  is lower than the pushing bar  87 , the pushing bar  87  will be return back due to the tension force of the tension spring Z 3 , and block the duplex ring  27  to restore the switch to operate normally. 
     d. Connection Supporting Mechanism 
     The connection supporting mechanism includes a case  1 , an end cover  8 , a housing  10 , a base  22 , a bedplate  68  and various connection fixing members etc. 
     As shown  FIGS. 11 and 12 , there is provided with several chambers separating from each other on the base  22 , each of which can fix two sets of arc extinguishers and one arc guiding plate, and receive a set of stationary and movable contacts. The base  22  is attached to the housing  10  by a fixing member, on which there is a mounting hole and a mounting slot for installing and fixing the switch. 
     There is a selective switch, a current limiting mechanism and a holding mechanism on the bedplate  68 , on the middle of which has a hole through which the movable bolt  19  can pass. On the assembling, the movable iron core  16 , the connection board  20  and the insulting connection frame  21  are first installed, then the tension spring Z 2 , the coil W 1  and the stationary iron core  15 , at last the bedplate  68  for fixing the various members is installed, and fixed by the fixing member, as shown  FIGS. 10 ,  11  and  12 . 
     (2) The Other Structure Switch 
       FIG. 17  is the structure of a switch in which the switch portion includes a current limiting mechanism, and the positions of the comprehensive protector and the current limiting mechanism are different from that of the aforesaid, but the operation is on the same principle. 
       FIG. 18  is a view schematically showing the structure of the electrical switch in which the contact is positioned on its top end. 
       FIG. 19  is a view schematically showing the structure of the electrical switch in which the contact is positioned on its top end and the pothook is different from that of the mentioned above. There is not selective switch in the  FIGS. 18 and 19 , which employ the electrical circuit shown as  FIG. 2 . 
     (3) The Side Pothook Electrical Switch 
     The attracting coil, the movable coil, the stationary iron core and the contact mechanism in said switch are connected in serial on one line, generally called a direct motion type, the present invention mainly introduces a switch in which the attracting mechanism, the tripping mechanism and the contact mechanism are installed in parallel, also called rotation type, and the structure is similar to the CJ10-60 contactor. 
       FIG. 20  is a top view showing the structure of the switch including a comprehensive protector in which the housing is separated and a cross section view taken along line F-F,  FIG. 22  is a cross section view taken along line E-E, in which the connecting shaft  84  and the connecting rod  85  are connected with the movable iron core and the movable contact to make them result in linkage. The selective switch and the comprehensive protector in the switch have the same structure and operational principle as the vertical bolt switch, only have different positions, the combination of the position may have various forms if needed, whose description will be omitted herein. As shown  FIG. 23 , the pothook switch and the vertical bolt switch are just opposite. 
     As shown  FIG. 20 , there are two current limiters W 3 , one of which is to restrain the limit short circuit current in the switch, it has many different structures, as shown  FIGS. 24 and 25 . In the figures, the reference number  40  represents a adjusting screw nut, the reference number  41  represents an insulting case, the reference number  42  represents an iron prop, the reference number  43  represents an iron core, B 5  represents a pushing bar made of nonferromagnetic material, the wire is wound outside the insulting case  41 . 
     When the over-current occurs in the switch, the iron prop  42  will be attracted to move along the direction F 6  so that the pushing bar B 5  also can move along the direction F 6 . 
     In the  FIG. 20 , the rotating shaft  64  has three rows of cogs, in which the number of cog  65  is three, each of cog corresponds to the pushing bar B 5  on the current limiter W 3  of each phase power supply, the number of the cog  87  is one, which corresponds to the pothook E 1 , the cog  62  corresponds to the insulting connection frame  21 . 
     When the over-current occurs in the switch, the coil W 3  attracts the pushing bar B 5  so that it can push the cog  65  to make the rotating shaft  64  rotate so as to make the cog  87  push the pothook E 1 , which can trip off the movable bolt  19  resulting in the tripping of the switch, at this time, the cog  87  separates from the movable slide slice  29 , and the switch trips off so as to switch off its power supply, in addition, the cog  62  strikes the connection frame  21  to increase the breaking speed of the switch. 
     Some of side pothook type switches have single contact structure, as shown  FIG. 21 , whose contact is directly fitted on the connection frame  21 , and connected with the wire terminal  18  through the flexible wire  66 , the tail ends of the connection frame  21  and the connection bar  85  are provided on the connecting shaft  84 , which can rotate at the axle center of the shaft  84 , and have the same operational principle as the mentioned above. 
     (4) The Switch Starting-Up with Electrical Power and Holding with the Elasticity 
       FIG. 26  is a view schematically showing the structure of the switch turning on or off with electrical power and with resilience-holding, which employs the circuit shown as  FIG. 3 . 
     In the Figure, Z 1 , Z 6 , Z 8  and Z 9  are all springs, ST represents a manual stop button, SF represents a manual reset button, JR represents an overload action member, E 3  represents a temperature compensating plate, the other elements have been introduced above. When the switch is turned off, the movable bolt  19  is applied on the pothook E 1 . When the coil W 1  is powered on, the switch is closed, the movable bolt  19  is fallen into the hook of the pothook E 1 , the tension spring pushes against the pothook E 1  to make it hitch the movable bolt  19  such that the switch keeps closed. When it is needed to turn off the switch, the manual stop button ST is pressed down to make the coil W 2  be powered on so that the switch can be electrically turned off, the manual stop button ST is pressed down so that the switch can be manually turned off. 
     When an over-current, an overload and a phase failure occurs in the switch, it can make the connecting shaft B 1  rotate in the direction F 4  such that it can prevent the connecting shaft B 1  from blocking E 1  to move along the direction F 5 , and the pad  33  strikes the pothook E 1  to make it trip off the movable bolt  19 , resulting in the tripping of the switch, when it resets, the manual reset button ST is pressed down to turn off the switch. 
     All mentioned above switches may be changed into the resilience-holding switch, whose operational principle of the pothook and the movable bolt is shown as  FIG. 27 . 
     Accordingly, the switch portion of said switch have many forms of the combination, it has an electromagnetic holding type, an elastic holding type and a pushing-shielding holding type depending on different holding modes, it has a selective or nonselective type depending on whether there is a selection switch, and it has a switch with current limiter and a switch with no current limiter depending on whether there is a current limiter, which will not be illustrated individually herein. 
     3. The Comprehensive Protector 
     There are many kinds of different comprehensive protectors, it will be described several typical structures below. 
     (1) The Electromechanical Type -I 
       FIG. 29  is a front view showing the structure of the protector in which the housing is separated and a cross section view taken along line A-A,  FIGS. 11 and 12  are views schematically showing the switch combing with the cross section taken along line A-A,  FIGS. 18 and 20  are views schematically showing the switch combing with the cross section taken along line B-B. The protector in  FIG. 29  has the functions of over-current, overload and phase failure protection. W 3  represents an over-current element, which may be made as shown  FIG. 24  or  FIG. 25 , JR represents a thermal protection element, which can be bent toward the direction F 7  due to heat. The reference number  4  represents an overload adjusting bar, which can rotate at the axle center Q 1 , and adjust the overload current in the range of F. The connecting shaft B 1 , the overload adjusting bar  4 , the coil W 5  and the pushing plate  74  are fixed through the bracket  76 , and installed in the housing  70 . 
     The over-current element W 3  is inserted in the connecting plate  72 , which is fixed in the housing  70 , the pushing bar B 5  is close to the connecting shaft B 1 , as to the three-phase load, the shape of the connecting shaft B 1  is shown as  FIG. 28 , it has two lines of cogs, in which three of cogs in the row correspond to the pushing bar B 5  of the over-current element W 3 , three of four cogs in the column correspond to the thermal protection element JR, the other cog corresponds to the pushing plate  74 , the pushing plate  74  is fixed on the overload adjusting bar  4  at the axle center Q 2 , when the over-current or overload occurs in the switch, the pushing plate  74  pushes the compensating plate E 3  to make the connecting shaft B 1  rotate, the connecting shaft B 1  pushes the pushing plate  74  to make it push down the temperature compensating plate E 3  such that the temperature compensating plate E 3  can impel the switch K 1  to be turned off, resulting in the tripping of the switch. 
     As shown  FIG. 29 , the switch K 1  and the coil W 5  are preferably small-size relay, whose normally closed contacts are the switch K 1 , the coil W 5 , the coil W 4  and the iron core  9  comprise a phase failure control circuit, as shown  FIG. 33 . Each phase of the coil W 4  has a structure which employs a single iron core, and an output from a single coil, in which three-phase coils are connected in serial with each other, and whose output is rectified, filtered and then inputted into the coil W 5 . If the three-phase electrical sources are balanced and powered on, the output from the coil W 4  is zero. If the phase failure occurs, then an output is produced so that the switch K 1  is attracted by the coil W 5 . The action value of the coil W 5  is selected according to the rated current, in which there exists an unbalance 20% of the three-phase electrical sources, that is, it allows the coil W 4  to output 20% of the rated current, but the coil W 5  may not act for a long time. 
     (2) The Electromechanical Type -II 
       FIG. 30  is a front view showing the structure of the protector and a cross section view taken along line A-A,  FIG. 17  is a view schematically showing the protector combing with the switch, the protector has the functions of a overload and a phase failure protection, in the figure, R 2  represents an operational lamp. 
     In  FIG. 30 , the phase failure action mechanism is comprised of an over-current bar B 2 , a spring Z 6 , a tension spring Z 1 , a shield E 2 , the coil W 4  and the coil W 5 . When the phase failure occurs in the switch, the coil W 5  attracts the shield E 2  to make it drop out of the over-current bar B 2 , then the over-current bar B 2  is ejected due to the elastic force of the spring Z 6  to drive the switch K 1  to break the contact. As shown  FIG. 31 , the switch K 1  is an elastic copper sheet, on which there are two semicircle contacts. After the over-current bar B 2  springs up, it is apparent to be higher on the surface of the protector, as shown  FIG. 32 , if it needs to reset, the over-current bar B 2  is only pressed down. 
     In the  FIG. 30 , the overload action mechanism is comprised of the overload bar B 4 , the connecting shaft B 3 , a compensating sheet E 3 , a thermal element JR and a spring Z 7 . As shown  FIG. 34 , the connecting shaft B 3  and the compensating sheet E 3  have three cogs in one line, each of which corresponds to the overload element in each phase, the front end of the compensating sheet E 3  is formed into a pothook which can hook the overload bar B 4 , the rear end of the compensating gauge E 3  is clamped in the connecting shaft B 3  whose two ends are cylinders for fixing and rotating, a spring Z 9  pushes against the connecting shaft B 3  to make it hook firmly the overload bar B 4 , the thermal element JR in each phase sticks to the cogs of the connecting shaft B 3 , as shown  FIG. 35 , when the thermal element JR can be bent due to the heat to make the connecting shaft B 3  rotate, such that the compensating a sheet E 3  can drop out of the overload bar B 4 , the overload bar B 4  springs up to break the switch K 1 , it is apparent to be higher on the surface of the protector, as shown  FIG. 36 , if it needs to reset, the overload bar B 2  is only pressed down. The compensating gauge E 3  is to compensate the temperature of the thermal protection. 
     In order to adjust the over-current, the platform  77  on the overload bar is formed into an eccentric circular, whose radius from the lower point to the high point is selected according to the degree of curve of the thermal element on which the current is applied,  FIG. 37  is a view showing the structure of the overload bar and the platform  77 ,  FIG. 38  is a view showing the structure of the bracket  76 , which can fix the over-current bar B 2 , the connecting shaft B 3  and the overload bar B 4 . 
     (3) The Mechanical Releasing Type 
       FIG. 26  is a view schematically showing the structure of the mechanical releasing electrical switch, the left side in the figure is a comprehensive protector, whose structure and principle have been described above, and will be omitted herein. 
     (4) The Electrical Releasing Type 
       FIG. 18(   a ) is a view showing the circuit diagram of the structure of the electronic releasing comprehensive protector, in which the coil W 4  is a mutual inductor for detecting the current of the main loop circuit, DP is a transformer of the electrical source, AD is an electronic controller, which may be an integrated circuit or use directly a single chip processor. The operation of the electronic comprehensive protector is varied with the current detected on the W 4 , it is determined whether there exists an over-current, an overload and a phase failure by comparing the loads, and it is further determined whether the protector needs to be released based on the result of the comparison. 
     The controller employing the single chip processor may be designed to have various functions, such as displaying each phase current and voltage of the controlled load, and displaying the environment temperature, moisture, time and the total number of starting-up, it may record the phase current, voltage or phase sequence of the phase failure of the controlled load before the releasing when the over-current, the overload or the phase failure occurs every time, it also may use an audible and visual alarm. 
     The electronic protector may be integrated with the electromechanical protector, thereby forming a comprehensive protector, that is to say, the comprehensive protector has either the electromechanical structure and function, or the electronic structure and function, in  FIG. 29 , the reference number represents an electronic controller. 
     4. The Operation of the Electrical Switch 
     The operation of the electrical switch may be illustrated by the drawings above, now it is taken as an example by  FIGS. 11 ,  12  and  17 . 
     When the selective switch directs to the remote control position D 1 , the switch K 2  and K 3  are turned on, at this time, the switch may be operated remotely by a button. If the button QA is switched on, the coil W 1  is powered on, and the switch is attracted to be closed, at this time, the movable contact  14 , the movable iron core  16 , the movable bolt  19 , the connecting plate  20  and the insulting connection frame  21  can move along the direction F 1 , the switch can be closed, the movable contact  14  and the stationary contact  17  are connected, the coil W 2  is powered on immediately so that the pothook E 1  can be attracted and closed, thereby resulting in the movable bolt  19  being locked by the pothook E 1 . At this time, although the coil W 1  is powered off, the coil W 2  is powered on to make the pothook E 1  hook the movable bolt  19  so as to keep the switch closed. If it needs to break the switch, the switch TA is opened to make the coil W 2  be powered off, so that the pothook E 1  is not attracted to disconnect with the movable bolt  19  because the component force is produced on the inclined surface X of the pothook E 1  due to the tension force of the tension spring Z 1  applied on the pothook E 1  and the pressure applied on the movable bolt  19  by the spring  22 , after the pothook E 1  dripping out of the movable bolt  19 , the movable contact  14 , the movable iron core  16 , the movable bolt  19 , the connecting plate  20  and the insulting connection frame  21  can move along the direction opposite to the direction F 1 , therefore, the switch can be broken. 
     When the selective switch directs to the stop position D 2 , no matter what operation the switch was, the switch is broken, and the remote control is out of work. 
     When the selective switch directs to the direct connection position D 3 , the switch is switched on immediately. 
     When the selective switch directs from the direct connection position D 3  to the direct connection locking position D 4 , the pushing block  32  firstly pushes against the pothook E 1 , then the switch K 2  and SA are turned off, the switch can be closed by the pushing block  32  pushing against the pothook E 1 , thereby forming a pushing block holding type switch. When the switch needs to be stopped on the position D 4 , it is only returned back to the position D 2 . 
     When the switch is closed on the position D 1  or D 3 , if the overload or the phase failure occurs, the contact K 1  in the comprehensive protector will be disconnected to make the coil W 2  be powered off, such that the switch can be broken. Only when the comprehensive protector is reset, the switch will operate normally. If the over-current occurs in the switch, it will be happen as described above, which will be omitted herein. 
     When the over-current occurs in the switch on the position D 4 , since the pushing block  32  is made of elastic material, the pushing bar  87  may compress the pushing block  32  to disconnect the pothook E 1  such that the pothook E 1  can release from the movable bolt  19 , thereby resulting in the switch tripping out. 
     As to the nonselective switch, there is provided with a mechanism for over-current displaying, analyzing and resetting on the bracket  69 , which can control the switch K 2  shown as  FIG. 2 .  FIG. 46  is a view showing the structure of the mechanism which is on the closed state. In the figure, the bar  26  is a cylinder with a bowl-shaped duplex ring  27  in the middle of it, the switch K 2  is a normal open button, Z 5  is a spring, the reference number  69  is a bracket. When it operates normally, the pushing bar  87  presses against the duplex ring  27 , the switch K 2  is turned on, when the over-current occurs in the switch, the pushing bar  87  can disconnect from the bar  26 , thereby the bar  26  can spring up to make the switch K 2  be turned off, as shown  FIG. 47 . Only when the bar is reset, the switch can operate normally. 
     The Measures Improving the Performance of the Switch 
     1. Making Use of the Movable Arc Contact to Prolong the Life Span of the Contact 
       FIG. 39  is a view schematically showing the structure of the movable arc contact, in which T 1  is a movable contact, T 2  is a stationary contact, T 3  is a movable contacting sheet, T 4  is a stationary contacting sheet. As is well known, when two charged bodies are close to each other, the electric charges will be discharged from the top end nearby. The movable arc contact makes use of the principle to make the electric arc be discharged from the contact position to the other position, then the electric arc can be entered into the arc extinguisher. 
     2. Changing the Contact Shape to Increase the Contacting Area of the Contact 
     The contact is designed to form a V-shape, as shown  FIG. 40 , compared with the semicircle or plane contact in the prior art, the contacting area of the contact can be increased, and the contacting resistance can be reduced. 
     3. The Fuse Provided in the Switch to Limit the Maximum Short Circuit Current 
     As shown  FIG. 41 , a fuse  94  is added in each phase main electrical circuit to limit the maximum short circuit current. 
     4. Adding the Releasing Circuit of the Coil or Employing Twin Coil. 
     5. The Iron Core Disconnecting from the Movable Bolt to Increase the Breaking Speed 
     In order to increase the breaking speed of the switch, the switch can break the movable iron core from the movable bolt to lighten the weight of the movable bolt in breaking, such that the breaking speed can be increased.  FIG. 42  is a view schematically showing the structures of the movable iron core and the movable bolt, in which the movable bolt  19 , the connecting plate  20 , the insulting connection frame  21  and the movable contact  14  are connected together. Two connecting plates on which a pair of hooks  96  are provided define a space in which the movable bolt  19  is formed. when the coil W 1  is powered on, the movable iron coil  16  is attracted because the hooks  96  hook the movable iron coil  16  to allow it to drive the movable bolt  19  and movable contact  14  to close together. When the coil W 2  is powered, the pothook E 1  hooks the movable bolt  19  to close the switch. When the coil W 1  is powered off, the movable iron is pushed to its original position by the spring Z 0 , the movable iron coil  16 , the movable contact  14  and the movable bolt  19  are then separated. If the switch is dropped out, the movable contact will be broken at lower weight and a higher speed thereby improving the short-breaking capacity of the switch. 
       FIG. 42  is a view schematically showing the structures of the movable iron core and the movable bolt employing two release springs,  FIG. 43  is a view schematically showing the structures of the movable iron core and the movable bolt employing one release spring. 
     6. Making Use of the Over-Current Percussion Arrangement Mechanism to Increase the Breaking Speed 
     The present invention is designed to make use of the energy produced by the over-current in the switch to strike the movable bolt, thereby improving the breaking speed. 
       FIG. 20  is one of said structures, whose operational principle has been described above. 
     Said switch stated above may be changed into a percussion type switch, as shown  FIG. 44 , the coil W 3  is a horizontal type, the connecting shaft  64 , the pushing bar  87 , the striking bar  65  and the attracting iron  86  are integrated. When the over-current occurs in the coil W 3 , the attracting iron  86  is attracted, and the pushing bar  87  pushes the pothook E 1  along the direction F 1  to make it drop out of the movable bolt  19 . At this time, the striking bar  65  strikes the movable bolt  19  to make it be broken at a higher speed, thereby improving the over-current breaking capacity of the switch. 
     7. Making Use of the Building Block System 
     The switch can make use of the building block system, if needed, it can be equipped with various additional function, such as a current leakage protection module etc. 
     8. The Other Kinds of Switch 
     The switch may be formed into an explosion protection switch or a commutation switch. The contact mechanism or the whole switch only needs to be sealed in the explosion protection switch, or the contacts of the switch are located into the vacuum or the arc extinguishing material. 
     The present inventor has seen a vacuum direct current contactor in which the attracting coil is bigger, if the holding mechanism according to the present invention is applied into it, the effect of saving energy will be better. 
     The Description of the Preferred Embodiments of the Electrical Switch 
     For the purpose of the description of the structure and the function of the electrical switch, there will be described by taking the model machine made by the present inventor as an example. 
     1. The Structure of the Example of the Switch 
       FIGS. 48 ,  49 ,  50 ,  51  and  52  are views showing the structure of the example of the switch, in which J represents a normal assistant contact set, whose structure is same as the assistant contacts in the contactor CJXI, in which the shaft  94  has a movable assistant contact, and it can run through, and move up and down in the contact set, Z 8  is a spring. When the switch is on the startup, the spring Z 8  can make the contact J 1  be turned on and the contact J 3  be turned off. When the switch is closed, the insulting frame  21  moves up to push the shaft  94  to make the contact J 1  be turned off and the contact J 3  be turned on. There are two sets of assistant contacts in the switch, in which one of sets is for its use, the other set is for output. The contact sets are embedded into a recess in the middle of two sides of the housing  10 , and clamped by the case  1 . 
     It is seen from  FIGS. 50 and 52  that the switch is fixed and packaged by the base  22 , housing  10  and the case  1 . There are three chambers in the lower portion of the housing  10 , in which the movable contact, the stationary contact, the arc extinguisher and the arc guiding plate are received respectively, there are four pillars on the housing  10 , which are in one plane, and can receive the movable iron core, the stationary iron core, the movable bolt, the coil W 1  and the base  22 , an elongated slot is provided on the middle of the plane which can connect the upper and lower portion, there are slide paths on the sides of the slot, on which the insulting frame  21  can slide, as shown  FIG. 49 . The insulting frame can support the movable iron core and three sets of movable contacts, as shown  FIG. 59 , the form of the insulting frame connecting with the movable iron core and the movable contacts are same as that of the contactor CJX 2 . 
     The bedplates  68  are fastened on four pillars in the housing  10  by the fastener  31 , it has a shape of right angle. The selective switch and the holding mechanism are fastened by the fastener on the bedplate  68 , E 1  employs a pothook, the movable bolt  19  can pass through a square hole in the middle of the bedplate  68 , whose sides can fasten the over-current mechanism by the fastener. 
     The miniature buttons K 4 ,K 5  are fixed on the two holes of the bracket  88 , the upper end of the button can pass through the hole on the case  1 , and be exposed outside the case  1  for operation. 
     The simplified electrical switch does not need a selective switch, only the holding mechanism and the over-current mechanism can be remained, the turnbutton  2 , the button K 4 , the button K 5 , the duplex ring  27 , the movable slide slice  29  and the stationary slide slice  30  in  FIGS. 50 and 52  are all omitted, only the bracket  88  is left for fixing the attracting iron  86  and the pushing bar  87 . 
     Some electrical switches are simpler, which only keep the holding mechanism. The selective switch and the current limiting mechanism are omitted, the sides of the bedplate  68  are also omitted, some other switches only keep the holding mechanism and the selective switch. 
     The electrical circuit in the simplified switch is also simple, in which the buttons K 2 , K 3 , K 4  are all omitted and shorted, the button K 5  is omitted and open. 
     2. The Electrical Circuit and the Control in the Switch 
     The exemplary switch use the electrical circuit shown as  FIG. 51 , compared with  FIG. 1 , which has only a normal open assistant contact, and whose selective switch uses double-position double-switch. When the turnbutton  2  is parallel with the main loop circuit, as shown  FIG. 53 , the switch is on the control position, which corresponds to the connection position(a) in  FIG. 55 , at this time, the buttons K 2  and K 3  in the switch are turned on, the remote control is operated by the buttons QA and TA, the near control is operated by the miniature buttons K 4 ,K 5  in the switch. 
     When the turnbutton  2  is vertical to the main loop circuit, as shown  FIG. 54 , the switch is on the stop position, which corresponds to the stop position(b) in  FIG. 55 , at this time, the buttons K 2  and K 3  in the switch are turned off, the miniature buttons K 4 ,K 5  are shield by the turnbutton  2  so that the switch can not be closed. 
     3. The Over-Current Control in the Switch 
       FIG. 56  is a view schematically showing the structure of one current limiter mechanism in the exemplary switch, in the figure, the reference number  86  represents a pushing plate, as shown  FIG. 57. 0Z  is a rotating fixed pivot of the pushing plate  86 , it is located in the slots which are on the sides of the bedplate  68 , two sides of the pushing plate  86  are just installed in two slots, the lower side of the pushing plate  86  is a wide side, which corresponds to the pushing bar B 5  of the current limiter W 3 , the top side is a cylinder, which is embedded in two side slots of the bracket  88  to block the turnbutton bar  26 . The reference number  87  represents a pushing bar, as shown  FIG. 58 , whose two front pothooks can hook the cylinder in the top side of the pushing plate  86 , the rear shaft is located in two side slots of the bracket  69 , the tension spring Z 3  is tensioned between the pushing bar  87  and the conducting magnet plate  23 . 
     When the switch is closed, if the pushing bar B 5  moves along the direction F 6  due to the over-current, it will push the pushing plate  86  to make it rotate at the fixed pivot OZ, and pull the pushing bar  87  to make it push the pothook E 1  so that the pothook E 1  can drop out of the movable bolt  19 , thereby resulting in the tripping of the switch. At this time, the pushing plate  87  separates from the shield of the duplex ring  26  to make it move along the direction F 3 , thereby leading to the movable and stationary slide slices in the switch separating from each other. After the over-current is relieved, the shield of the duplex ring  26  is pressed to be lower than the pushing plate  86 , the tension spring Z 3  pulls the pushing plate  86  and the pushing bar  87  to make the system reset. 
     4. The Assembly of the Exemplary Switch 
     With reference to the drawings above, the processes in assembling the exemplary switch include: firstly, the movable iron core  16 , the connecting board  20  and the insulting frame  21  are assembled together, and inserted into the elongated slot in the housing  10 ; then, the tension spring Z 2 , the coil W 1  and the stationary iron core  15  are installed; next, the movable bolt  19  is fastened on the connecting board  20 . The bedplate  68  to which the holding mechanism, the selective switch and the over-current mechanism are attached is overlapped on the stationary iron core  15 , there is a rubber pad  93  provided between the pushing plate  68  and the stationary iron core  15 , the pushing plate  68  is fastened by the fastener  31  on four pillars in the housing  10 , and the stationary contact  17  is fixed on the housing  10 , one end of the coil W 3  is fixed by the fastener on the stationary contact  17 , and the other end of the coil W 3  is fixed on the wiring terminal  18 , the movable contact  14  is inserted into the upper end of the insulating frame  21 , the arc extinguisher  6  and the arc guiding plate  89  are installed into the chambers in the housing, the base  22  is attached onto the housing  10  by the fastener, and the assistant contact sets are placed the recesses on the two sides in the housing, KJ is fixed on the pushing plate  68 , and wired as shown  FIG. 51 , the housing  10  is fixed on the magnet conducting plate  23 , the processes of assembling the switch have been completed. 
     While the present invention has been described and shown with reference to the preferred embodiments chosen for purpose of illustration, the described above examples and embodiment modes according to the present invention are to be considered in all respects only as illustrative and not as restrictive. It should be apparent that such modifications could be made thereto by those skilled in the art without departing from the scope of the appended claims and the equivalents thereof.