Abstract:
The invention concerns a protection relay, in particular of the thermal type, recessed relative to its front face ( 24 ), a recess acting as through passage for interconnection of the conductors (C) between the terminals of the relay control ( 23 ) and of the contact switch ( 16 ). The recess ( 27 ) is concealed in normal operation by a shutter consisting of a flap ( 26 ) or a fixed part ( 26 ′) of the housing ( 20 ). The interconnection conductors can consist of individual cables (C) or can be integrated to a precabling addition ( 40 ) housed in the recess.

Description:
FIELD OF THE INVENTION 
     This invention relates to a protection relay, and particularly a thermal relay, capable of being connected to a contactor and including a box provided with power connection terminals on the input and output sides, and control terminals, and provided on the front with manually operated devices for actuation or adjustment. As is well known, the power terminals on the input side and the control terminals of this type of protection relay must be connected to the corresponding power and control terminals of an adjacent contactor. 
     The invention relates also to a protected control set including such a protection relay. 
     BACKGROUND OF THE INVENTION 
     Documents EP-256 900 and EP-828 270 disclose thermal protection relays in which the box is provided with a flap that can fold down on selection, control or adjustment devices that must remain inaccessible in normal service, by pivoting or by sliding. The flap leaves a stop button and a reset button accessible at all times. The operator can thus use the stop button to freely cut off the power line through a contactor, the coil of which is connected to the thermal relay or through the reset button, he can manually reset the thermal relay into its operation state after it has tripped. On the other hand, the operator can only take action on the adjustment button or on the manual/automatic mode switch (H/A) when the flap is opened. 
     The power interconnection between the relay and the contactor remains hidden as long as the two devices are assembled. On the other hand, the control interconnection that the user has to make between the relay control terminals and the contactor control terminals leaves the conductors on the front of the equipment visible and accessible to be manipulated. This can be a serious problem. 
     The purpose of the invention is to provide a masked control interconnection for the relay and the contactor using simple means. 
     SUMMARY OF THE INVENTION 
     According to the invention, the relay box includes at least one recess setback from its front face used for the passage of an interconnection conductor between a relay control terminal and a contactor control terminal, the said recess being masked in normal service by a cache, or cover, and housing part of a prewiring additive, or accessory, provided with the interconnection conductor(s), on the front. 
     The cache may be a flap that enables and prohibits operation of an actuation device or a limited access adjustment device, when in the open or closed position respectively. Alternatively, the cache may simply be a fixed part of the protection relay box. 
     The prewiring addition may be housed in the recess, either when the recess is provided on the front of the protection relay box that can be concealed by a flap, or when the recess is provided in a fixed part of the box setback from this front face. 
     The invention also relates to a protected control set formed by the protection relay and the contactor laid out and interconnected as described above. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     We will now describe a non-limitative embodiment of the invention with reference to the attached drawings. 
     FIG. 1 shows a side view of a protected electrical control set composed of a contactor and a thermal type protection relay. 
     FIG. 2 shows a perspective view of the set in FIG.  1 . 
     FIGS. 3 and 4 show perspective views of the protection relay with its flap open, without a prewiring additive and with a prewiring additive respectively; 
     FIGS. 5 and 6 show perspective views of a variant embodiment of the protection relay, provided with a prewiring additive with the flap open and closed respectively, the prewiring additive being shown before and after its installation respectively. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The control and protection set shown includes a contactor with a box  10  and a thermal protection relay with a box  20  assembled to the contactor. The box  10  of the contactor is provided with input power terminals  11  and output power terminals  12 , and a control—instrumentation terminal block  13  on the front side, in other words on the side accessible to the user. The term control used later in this description refers indifferently to the instrumentation (or signalling) and the control (or switching) function that changes the state of the contactor by energizing the contactor coil. The control terminal block  13  projecting forwards beyond the front face  14  of the box  10  on which openings are formed through which a tool can access the terminals  11 ,  12  is provided with input side control terminals  15  and output side control terminals  16  that can be connected to a high potential and a low potential respectively. 
     The box  20  of the thermal relay is provided with input power terminals  21  consisting of pins that can enter into the contactor output terminals  12 . This box  20  is also provided with output power terminals  22  to be connected to a load, and control terminals  23  to be connected to some of the output control terminals  16  of the box  10  using rigid or flexible conductors C, and that may be connected to signalling devices. These conductors are laid out to be mechanically connected to each other in the form of additional prewiring. Note that the terminals  23  are located on the output side, on the side opposite to the contactor. 
     The main face of the box  20  is provided with limited access devices  24 , particularly with actuation or adjustment functions, and permanent access devices  25 , particularly with a stop and/or reset function. The limited access devices  24  may for example be an adjustment button  24   a  and a selection button  24   b  to select the operating mode (manual or automatic) of the relay, and permanent access devices  25  may for example be a reset and stop button or two separate buttons performing these functions. 
     The box  20  also includes a flap  26  forming its front face  24 . The front face  24  would obviously be fixed if there were no such flap. The flap  26  enables access to devices  24  when in the open position (see FIGS. 3,  4  and  5 ) and prohibits access to these devices when in the closed position (see FIGS. 1,  2  and  6 ). It includes an opening  26   a  that can be used to access devices  25  at all times. The flap  26  is able to fold down on devices  24 ,  25  by pivoting or sliding with respect to box  20 . 
     A recess is provided setback from the front  24  of the box  20  of the thermal relay, such as a channel  27  designed to carry two conductors, and for example including two separate passageways on each side of the stop and reset button  25 . The channel is located close to the right of the box so that its passageways are approximately at the same level as the two control terminals  23  of the relay. The channel  27  is formed in the box  20  or in the flap  26  and opens up on the flat top surface  28  of the box  20  adjacent to the contactor through a flared opening  29  through which the conductors can easily pass towards the corresponding output terminals  16 -A 2  and  16 - 14  of the contactor. The opening  29  leads to a space  13   a  open towards the front and delimited by the control terminal block  13 , the front  14  of the contactor and the top surface  28  of the relay. 
     The thermal relay is also laid out so that an additional control prewiring subset provided with interconnection conductors can be fitted on the front; 
     the addition is shown in a first variant in FIG.  4  and in a second variant in FIGS. 5 and 6. 
     The prewiring addition  30  shown in FIG. 4 is housed in the channel  27  and includes two approximately rigid interconnection conductors  31 ,  32 ; in their lower part, the conductors  31 ,  32  are connected by an insulating mounting  33  and can fit into the terminals  23  on the opposite side of the contactor; at their top, they are bent to penetrate into the terminals  16  of the contactor. In the closed position, the flap  26  conceals devices  25  and the channel  27  and contributes to concealing and holding the conductors  31 ,  32  in place. 
     The prewiring additive  40  shown in FIGS. 5 and 6 is housed in a recess  27 ′ of the relay box  20 . The recess  27 ′ includes two channels located behind a fixed part  26 ′ of the box close to its front face; this part  26 ′ forms the cache that will hide it, such that the channel  27 ′ opens up firstly to face  28  and secondly directly into the recesses of the two relay control terminals  23 , through the inside of the box  20 . Note that these terminals are therefore accessible through the top and the inside of the box, and through the bottom of the outside of the box. The additive  40  includes two rigid interconnection conductors  41 ,  42 . The conductors  41 ,  42  are connected at their top by an insulating mounting  43  provided with openings  43   a  through which a tool can be passed to access the contactor power terminals  12 ; they terminate at the top by two pins  41   a,    42   a  that will be inserted into the contactor terminals  16  and at the bottom by two pins  41   b,    42   b  that will penetrate into the two channels of the recess  27 ′ to fit directly into the recesses of the relay control terminals  23 , perpendicular to the face  28  of the box  20 . The pins may be rigid, or they may be designed to allow an adjustment to the spacing or orientation. In this embodiment, the channels forming the recess  27 ′ also provide guidance when the additive  40  is inserted and they give excellent support to this additive. 
     The protection relay described can be used to connect flexible individual cables C or cables  31 ,  32  or rigid conductors  41 ,  42  forming part of a specific additive  30 ,  40  while providing the required cache.