Patent Publication Number: US-2011050413-A1

Title: Dual-warning protector having multiple protections

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a dual-warning protector having multiple protections. 
     2. Description of the Prior Art 
     Generally, there is a protector disposed between a telecommunication cable and a switchboard apparatus for preventing the equipment from being damaged because of a short circuit or a lightning strike. A conventional protector comprises a protection circuit and an alarm circuit. The protection circuit uses a thermistor and a semiconductor discharge tube for protecting it from over voltage or over current. The alarm circuit uses an illuminating member to activate a phototransistor which is adapted to start a light emitting diode to radiate light for providing a warning to remind the maintenance personnel of abnormal circuit. The conventional protector guides the surge to the ground wire via the protection circuit. However, the operating voltage is interrupted, which is unable to proceed to communication, causing an indirect loss. In addition, the conventional protector uses the phototransistor for a light control alarm, which has many shortcomings, such as large size, difficulty in packing, and light leakage or the like. The conventional protector is unable to remind the maintenance personnel of high voltage when the parts in the protector have a breakdown or aging, which may cause an accident because of getting an electric shock. Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve this problem. 
     SUMMARY OF THE INVENTION 
     According to the present invention, there is provided a dual-warning protector having multiple protections, disposed between a telecommunication cable and a switchboard apparatus, comprising: 
     a protection circuit including two protection modules which are identical and disposed on two different signal lines respectively, the protection modules each including a thermistor connected to one of the signal lines in the way of series connection, a fuse connected to the signal line in the way of series connection, a semiconductor discharge tube connected between the signal line and a ground wire, and a voltage dependent resistor connected between the signal line and the ground wire; 
     a first alarm circuit including two first illuminating modules and a light control alarm module, the two first illuminating modules being respectively connected to the signal lines in the way of parallel connection, the light control alarm module being disposed at a rear end of the protection circuit and connected to the ground wire in the way of series connection, the first illuminating modules each including a first resistor and a first light emitting diode, the light control alarm module including a phototransistor and a third light emitting diode, the phototransistor being disposed close to the first light emitting diode; and 
     a second alarm circuit including two second illuminating modules which are respectively connected to the signal lines in the way of parallel connection, the second illuminating modules each including a second resistor and a second light emitting diode, the second resistor having a resistance valve much greater than that of the first resistor of the first illuminating module. 
     Accordingly, when there is a surge, the protection circuit will absorb it for providing a protection effect. With the thermistor, the operating voltage is kept when the protection circuit is acting for ensuring the communication not being interrupted. Besides, when high current passes through, the fuse will be blown to form a broken circuit, achieving a protection for the circuit. Furthermore, when there is high voltage in the protector, the maintenance personnel is able to know it via the second alarm circuit, preventing the maintenance personnel from getting an electric shock. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view showing the circuit of a preferred embodiment of the present invention; 
         FIG. 2  is a side view of a protection module of the present invention; and 
         FIG. 3  is a front view of the protection module of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings. 
     As shown in  FIG. 1 , a protector  100  according to a preferred embodiment of the present invention is disposed between a telecommunication cable and a switchboard apparatus, and comprises a protection circuit  10 , a first alarm circuit  20 , and a second alarm circuit  30 . 
     The protection circuit  10  includes two protection modules  11  which are identical and disposed on two different signal lines aa′ and bb′, respectively. The protection module  11  provided on the signal line aa′ is given as an example. The protection module  11  includes a thermistor  111  connected to the signal line aa′ in the way of series connection, a fuse  112  disposed in front of the thermistor  111 , a semiconductor discharge tube  113  connected between the signal line aa′ and a ground wire E, and a voltage dependent resistor  114  connected between the signal line aa′ and the ground wire E. The semiconductor discharge tube  113  is located at a front end of the thermistor  111 , and the voltage dependent resistor  114  is located at a rear end of the thermistor  111 . The starting voltage of the semiconductor discharge tube  113  is greater than that of the voltage dependent resistor  114 . 
     The first alarm circuit  20  includes two first illuminating modules  21  and a light control alarm module  22 . The two first illuminating modules  21  are respectively connected to the signal line aa′ and the signal line bb′ in the way of parallel connection. The light control alarm module  22  is disposed at a rear end of the protection circuit  10  and connected to the ground wire E in the way of series connection. Each of the first illuminating modules  21  includes a first resistor  211  and a first light emitting diode  212 . The light control alarm module  22  includes a phototransistor  221  and a third light emitting diode  222 . The phototransistor  221  is disposed close to the first light emitting diode  212 . The second alarm circuit  30  includes two second illuminating modules  31  which are respectively connected to the signal line aa′ and the signal line bb′ in the way of parallel connection. Each of the second illuminating modules  31  includes a second resistor  311  and a second light emitting diode  312 . The resistance valve of the second resistor  311  is much greater than that of the first resistor  211 . 
       FIG. 2  is a side view of the protection module.  FIG. 3  is a front view of the protection module. The protection modules  11  are disposed on a circuit board  40 . The thermistor  111  has a top and a bottom connected with first copper plates  115 . The first copper plates  115  have connecting legs  116  which are connected with the signal line aa′ so that the thermistor  111  is connected to the signal line aa′ in the way of series connection. The connecting leg  116  at the front end of the thermistor  111  is connected with the fuse  112  in the way of series connection. In this embodiment, the fuse  12  is a thermal fuse. The first copper plates  115  extend a specific distance in the same direction to form a space therebetween for stacking up the semiconductor discharge tube  113  and the voltage dependent resistor  114  in sequence. A second copper plate  117  is provided between the semiconductor discharge tube  113  and the voltage dependent resistor  114 . The second copper plate  117  has a connecting leg  118  which is connected with the ground wire E. Accordingly, the semiconductor discharge tube  113  and the voltage dependent resistor  114  are connected between the signal line aa′ and the ground wire E. Besides, the circuit board  40  is formed with a through hole  41  corresponding in position to the voltage dependent resistor  114  for insertion of the voltage dependent resistor  114  so as to decrease the height of the protection module  11 . 
     Referring to  FIG. 1 , under a normal status, the telecommunication cable and the switchboard apparatus has an operating voltage (48V) so that the semiconductor discharge tube  113  is in an open circuit status. The resistance valves of the first resistor  211  and the second resistor  311  are much greater than that of the thermistor  111  so that the communication current of the telecommunication cable are transmitted from a,a′ ends to b, b′ ends of the signal lines aa′, bb′, respectively, through the thermistor  111  into the switchboard apparatus. 
     During communication, if there is a surge and the voltage of the surge is greater than the starting voltage of the semiconductor discharge tube  113 , the semiconductor discharge tube  113  will form a closed circuit and guide most of the current to the ground wire E. The resistance valve of the thermistor  111  will rise quickly so that partial current is forced to go through the first illuminating module  21  of the first alarm circuit  20  to start the first light emitting diodes  212  to radiate light. Meanwhile, the phototransistor  221  of the light control alarm module  22  is shone to trigger the third light emitting diode  222  to radiate light for warning the maintenance personnel of abnormal circuit. Because the resistance of the second resistor  311  of the second alarm circuit  30  is greater than those of the first resistor  211  and the thermistor  111 , only minimal current passes therethrough, which is unable to start the second light emitting diode  312 . The current passing through the thermistor  111  will be absorbed by the voltage dependent resistor  114  to keep the voltage (50V) which is slightly greater than the operating voltage (48V) of the telecommunication cable and the switchboard apparatus. Therefore, the communication current will not be interrupted, proceeding to do communication. 
     When the voltage of the surge is less than the starting voltage of the semiconductor discharge tube  113 , the semiconductor discharge tube  113  will keep in an open status, without any action. At this time, the voltage of the thermistor  111  rises quickly so that partial current is forced to pass through the first illuminating module  21  of the first alarm circuit  20  to start the first light emitting diodes  212  to radiate light so as to trigger the light control alarm module  22  for warning the maintenance personnel of abnormal circuit. Meanwhile, the current passing through the thermistor  111  will be absorbed quickly by the voltage dependent resistor  114  and then be radiated in the form of heat to keep the voltage (50V) so that the communication current will not be interrupted. Because the resistance of the second resistor  311  of the second alarm circuit  30  is much greater than those of the first resistor  211  and the thermistor  111 , only minimal current passes therethrough, which is unable to start the second light emitting diode  312 . Thereby, the protector  100  provides multiple protection functions, including protecting the equipment, keeping the operating voltage, and not interrupting communication. 
     The parts in the protector  100  may become aging. In this embodiment, the semiconductor discharge tube  113  becoming aging is given as an example. When current greater than the operating voltage of the semiconductor discharge tube  113  is inputted from the “a” end, the semiconductor discharge tube  231  fails to form a closed circuit. Thus, the resistance valve of the thermistor  111  rises quickly to form high current, which will blow the fuse  112 . The current will be forced to go toward the first alarm circuit  20  and the second alarm circuit  30  for starting the third light emitting diode  222  and the second light emitting diode  312  to radiate light such that the maintenance personnel is able to know that the protector  100  has high voltage, preventing the maintenance personnel from getting an electric shock. 
     Although particular embodiments of the present invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the present invention. Accordingly, the present invention is not to be limited except as by the appended claims.