JP5522734B2 - Short-circuit current interrupting device and short-circuit current interrupting method - Google Patents

Description

  The present invention relates to a short-circuit current interrupting device and a short-circuit current interrupting method for preventing a short-circuit current from flowing through a circuit, and in particular, a short-circuit current interrupting for preventing a short-circuit current from flowing through a transmission line and a reception line of an exchange. The present invention relates to a device and a short-circuit current interruption method.

  FIG. 1 shows a transmission line TX, a reception line RX, and peripheral circuits of a normal exchange. As shown in FIG. 1, since the receiving line is connected to a power supply of −27 volts in a state where the overcurrent protection element PT is closed, the operation center voltage is −27 volts. Further, since the transmission line is connected to the ground, the operation center voltage is zero volts. A signal from the inside of the exchange is given to the transmission line TX via the mutual inductance M1. The signal on the reception line RX is given to the inside of the exchange via the mutual inductance M2. Diodes D1 and D2 are voltage limiters.

  Patent Document 1 discloses an example of a circuit protection device.

JP 2007-252081 A

  When the transmission line TX and the reception line RX of the circuit shown in FIG. 1 are accidentally short-circuited during telephone connection construction or the like, the voltage at the left terminal of the overcurrent protection element PT becomes zero volts, while the overcurrent protection element PT Since the voltage at the right terminal of-remains at -27 volts, a voltage of 27 volts is applied to the overcurrent protection element PT, thereby increasing the impedance of the overcurrent protection element. Therefore, it is possible to suppress a short circuit current from flowing through the transmission line TX. However, if a short-circuit current that exceeds the allowable value of the overcurrent protection element PT flows, or if the time during which the transmission line TX and the reception line RX are short-circuited is too long, the overcurrent protection element PT itself is damaged. There is a possibility.

  Therefore, in place of the overcurrent protection element PT, there is a need for a short-circuit current interrupting device that can prevent a short-circuit current from flowing or can prevent a short-circuit current from flowing in addition to the overcurrent protection element PT. It becomes.

  In the invention described in Patent Document 1, since the supply of overcurrent to the load circuit is detected by the current detection means, fluctuations in the power supply level cannot be directly detected. In the invention described in Patent Document 1, the supply of the power supply current to the load circuit is cut off by lowering the power supply voltage, and therefore cannot be applied when the load is an inductive resistor.

  Therefore, it is very difficult to apply the circuit protection device disclosed in Patent Document 1 to the circuit shown in FIG.

  Then, an object of this invention is to provide the short circuit current interruption device and the short circuit current interruption method corresponding to the structure of the normal exchange.

According to the first aspect of the present invention, the bias voltage supply means applies a first bias voltage based on the ground potential to one of the transmission line and the reception line, and the ground potential is applied to the other of the transmission line and the reception line. Is a short-circuit current interrupting device for an exchange to which a different second bias voltage is applied, between the bias voltage supply means and a line to which the second bias voltage is applied among the transmission line and the reception line. An overcurrent protection means disposed; a short-circuit detection means for detecting a short-circuit between the transmission line and the reception line based on a voltage change between the first bias voltage and the second bias voltage; and the short-circuit detection. When the short circuit is detected by the means, the supply of the bias voltage to the transmission line and the reception line from the bias voltage supply means is interrupted, and when the short circuit is not detected, the bias voltage supply means Comprising of a control means for controlling to continue the supply of the bias voltage, during the short, as well as blocking the flow of short-circuit current to the transmission line and the reception line by the overcurrent protection means, said control The supply of the bias voltage from the bias voltage supply means is interrupted by the means, whereby the first bias voltage is applied to one end of the overcurrent protection means and the second bias voltage is applied to the other end. There is provided a short-circuit current interrupting device characterized by avoiding the above.

Further, according to the present invention, the bias voltage supply means applies a first bias voltage based on the ground potential to one of the transmission line and the reception line, and the other of the transmission line and the reception line differs from the ground potential. 2 is applied, and a short-circuit current is cut off in an exchange in which an overcurrent protection unit is disposed between the bias voltage supply unit and the transmission line and the reception line to which the second bias voltage is applied. A method of detecting a short circuit between the transmission line and the reception line based on a voltage change between the first bias voltage and the second bias voltage; and When a short circuit is detected, supply of a bias voltage to the transmission line and the reception line from the bias voltage supply unit is interrupted. When a short circuit is not detected, the bias voltage supply unit supplies the bias voltage. And a control step for controlling to continue the supply of the astigmatism voltage, a time the short, as well as blocking the flow of short-circuit current to the transmission line and the reception line by the overcurrent protection means, in said control step By interrupting the supply of the bias voltage from the bias voltage supply means, the first bias voltage is applied to one end of the overcurrent protection means, and the second bias voltage is applied to the other end. A short-circuit current interrupting method is provided that is characterized in that it is avoided.

  According to the present invention, since a short circuit between the transmission line and the reception line is detected based on whether or not the voltage of the transmission line and the voltage of the reception line are close to each other, it is possible to cope with the configuration of a normal exchange.

FIG. 3 is a circuit diagram showing a transmission line TX, a reception line RX and peripheral circuits of a normal exchange. It is a circuit diagram which shows the transmission line TX, the reception line RX, and its peripheral circuit of the exchange to which the short-circuit current interruption device according to the embodiment of the present invention is added.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 2 shows a transmission line TX, a reception line RX and its peripheral circuit of an exchange to which a short-circuit current interrupting device according to an embodiment of the present invention is added. The short-circuit current interrupting device includes a short-circuit detecting unit including an NPN transistor TR1, resistors R1, R2, R3, and R4, and a disconnecting unit including a PNP transistor TR2, an NPN transistor TR3, and resistors R5, R6, R7, R8, R9, and R10. Including a control circuit. The part other than the short-circuit current interrupting device is a normal circuit.

  When the transmission line TX and the reception line RX are not short-circuited, since the operation center voltage of the transmission line TX is −27 volts, the base voltage of the NPN transistor TR1 is lower than the emitter voltage of the NPN transistor TR1. Therefore, no collector current flows through the NPN transistor TR1, and therefore the voltage at the terminal ALM is 3.3 volts.

  When the transmission line TX and the reception line RX are short-circuited, the voltage of the transmission line TX becomes zero volts. The resistance values of the resistors R1, R2, and R3 are set so that the base-emitter voltage of the NPN transistor TR1 exceeds the threshold value (about 0.7 volts) of the transistor TR1 when the voltage of the transmission line TX is zero volts. Is set. Therefore, when the transmission line TX and the reception line RX are short-circuited, a collector current flows through the NPN transistor TR1, and the voltage at the terminal ALM becomes zero volts.

  On the other hand, when the voltage at the terminal POWER_OFF is 3.3 volts, the emitter voltage and the base voltage of the PNP transistor TR2 are equal, and therefore no collector current flows through the PNP transistor TR2. Therefore, the base voltage of the NPN transistor TR3 is equal to the emitter voltage of the NPN transistor TR3. Accordingly, no collector current flows through the NPN transistor TR3 (the NPN transistor TR3 is turned off).

  The resistance values of the resistors R5, R6, and R7 are such that when the voltage at the terminal POWER_OFF is zero volts, the base-emitter voltage of the PNP transistor TR2 exceeds the threshold value (about 0.7 volts) of the PNP transistor TR2. Is set to The resistance values of the resistors R8, R9, and R10 are such that when the collector current flows through the PNP transistor TR2, the base-emitter voltage of the NPN transistor TR3 exceeds the threshold value of the NPN transistor (about 0.7 volts). Is set to Accordingly, when the voltage at the terminal POWER_OFF becomes zero volts, a collector current flows through the NPN transistor TR3 (the NPN transistor TR3 is turned on).

  Therefore, when the voltage at the terminal ALM is 3.3 volts, the control circuit sets the voltage at the terminal POWER_OFF to zero volts, and when the voltage at the terminal ALM is zero volts, the voltage at the terminal POWER_OFF is 3.3 volts. As a result, when the transmission line TX and the reception line RX are not short-circuited, the NPN transistor TR3 is turned on, the operation center voltage of the transmission line TX is set to −27 volts, and the transmission line TX and the reception line are set. When RX is short-circuited, the NPN transistor TR3 can be turned off so that a voltage of 27 volts is not applied across the overcurrent protection element PT.

  Further, when a circuit equivalent to the disconnection unit controls connection / disconnection of the portion A shown in FIG. 2, when the transmission line TX and the reception line RX are short-circuited, both ends of the overcurrent protection element PT are connected to both ends. The voltage of volts can be prevented from being applied.

  According to the present embodiment, since a short circuit between the transmission line and the reception line is detected based on whether or not the voltage of the transmission line and the voltage of the reception line are close to each other, it is possible to cope with the configuration of a normal exchange. .

  Further, according to the present embodiment, when a short circuit between the transmission line and the reception line is detected by the short circuit detection unit, the transmission line and the line that applies a bias voltage to the transmission line are disconnected. It can correspond to.

  A part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.

(Appendix 1)
A short circuit detecting means for detecting a short circuit between the transmission line and the reception line based on whether the voltage of the transmission line and the voltage of the reception line are close to each other;
Cutting means for cutting the transmission line and a line for applying a bias voltage to the transmission line when a short circuit between the transmission line and the reception line is detected by the short-circuit detection means;
A short-circuit current interrupting device comprising:

(Appendix 2)
A short circuit detecting means for detecting a short circuit between the transmission line and the reception line based on whether the voltage of the transmission line and the voltage of the reception line are close to each other;
Cutting means for cutting the receiving line and a line for applying a bias voltage to the receiving line when a short circuit between the transmitting line and the receiving line is detected by the short-circuit detecting means;
A short-circuit current interrupting device comprising:

(Appendix 3)
The short-circuit current interrupting device according to appendix 1 or appendix 2,
The short-circuit detection unit is characterized in that a short-circuit between the transmission line and the reception line is detected based on whether or not the voltage of the transmission line approaches the voltage of the reception line.

(Appendix 4)
The short-circuit current interrupting device according to appendix 1 or appendix 2,
One of the transmission line and the reception line is biased by ground,
The short-circuit detection means is configured to determine whether the voltage of the transmission line and the reception line, which is not the line biased by the ground, approaches the ground voltage. And a short circuit between the receiving line and the short circuit current interrupting device.

(Appendix 5)
The short-circuit current interrupting device according to any one of appendices 1 to 4,
The short-circuit detection means outputs a detection signal indicating whether the transmission line and the reception line are short-circuited,
The disconnecting means disconnects the transmission line and a line for applying a bias voltage to the transmission line when a disconnection signal indicates a disconnection request,
The short-circuit current interrupting device further includes a control unit that causes the disconnection signal to indicate a disconnection request when the detection signal is short-circuited between the transmission line and the reception line. Current interrupt device.

(Appendix 6)
A short-circuit detection step for detecting a short-circuit between the transmission line and the reception line based on whether or not the voltage of the transmission line and the voltage of the reception line are close to each other;
A disconnecting step of disconnecting the transmission line and a line for applying a bias voltage to the transmission line when a short circuit between the transmission line and the reception line is detected by the short-circuit detection step;
A method of interrupting a short-circuit current, comprising:

(Appendix 7)
A short-circuit detection step for detecting a short-circuit between the transmission line and the reception line based on whether or not the voltage of the transmission line and the voltage of the reception line are close to each other;
A disconnecting step of disconnecting the receiving line and a line for applying a bias voltage to the receiving line when a short circuit between the transmitting line and the receiving line is detected by the short-circuit detecting step;
A method of interrupting a short-circuit current, comprising:

(Appendix 8)
The short-circuit current interrupting method according to appendix 6 or 7,
In the short circuit detection step, a short circuit between the transmission line and the reception line is detected based on whether or not the voltage of the transmission line approaches the voltage of the reception line.

(Appendix 9)
The short-circuit current interrupting method according to appendix 6 or 7,
One of the transmission line and the reception line is biased by ground,
In the short-circuit detection step, the transmission line is determined based on whether or not the voltage of the transmission line and the reception line that is not the line biased by the ground approaches the ground voltage. And a short circuit between the receiving line and the short circuit current interruption method.

(Appendix 10)
The short-circuit current interrupting method according to any one of appendices 6 to 9,
In the short-circuit detection step, a detection signal indicating whether or not the transmission line and the reception line are short-circuited,
In the disconnecting step, when the disconnect signal indicates a disconnect request, the transmit line and a line that applies a bias voltage to the transmit line are disconnected,
The short-circuit current interruption method further includes a control step in which the disconnection signal indicates a disconnection request when the detection signal is short-circuited between the transmission line and the reception line. Current interruption method.

R1 to R10 Resistance TR1 NPN transistor TR2 PNP transistor TR3 NPN transistor

Claims (2)

An exchange in which a first bias voltage based on a ground potential is applied to one of a transmission line and a reception line from a bias voltage supply means, and a second bias voltage different from the ground potential is applied to the other of the transmission line and the reception line. A short-circuit current interrupting device of
An overcurrent protection unit disposed between the bias voltage supply unit and a line to which the second bias voltage is applied among the transmission line and the reception line;
Short-circuit detection means for detecting a short-circuit between the transmission line and the reception line based on a voltage change between the first bias voltage and the second bias voltage;
When the short circuit is detected by the short circuit detection unit, supply of the bias voltage to the transmission line and the reception line from the bias voltage supply unit is cut off. When the short circuit is not detected, from the bias voltage supply unit Control means for controlling the supply of the bias voltage to be continued,
With
At the time of the short circuit, the overcurrent protection unit prevents the short circuit current from flowing into the transmission line and the reception line, and the control unit cuts off the supply of the bias voltage from the bias voltage supply unit. A short-circuit current interrupting device that avoids applying the first bias voltage to one end of the overcurrent protection means and applying the second bias voltage to the other end. A bias voltage supply means applies a first bias voltage based on a ground potential to one of the transmission line and the reception line, and applies a second bias voltage different from the ground potential to the other of the transmission line and the reception line , A short-circuit current interruption method for an exchange in which an overcurrent protection means is disposed between the bias voltage supply means and a line to which the second bias voltage is applied among the transmission line and the reception line,
A short-circuit detection step for detecting a short-circuit between the transmission line and the reception line based on a voltage change between the first bias voltage and the second bias voltage;
When the short circuit is detected in the short circuit detection step, the supply of the bias voltage to the transmission line and the reception line from the bias voltage supply unit is cut off. When the short circuit is not detected, from the bias voltage supply unit A control step for controlling the supply of the bias voltage to be continued;
With
At the time of the short circuit, the overcurrent protection means prevents the short circuit current from flowing into the transmission line and the reception line, and the supply of the bias voltage from the bias voltage supply means is interrupted in the control step. A method of interrupting a short-circuit current, wherein the first bias voltage is applied to one end of the overcurrent protection means and the second bias voltage is not applied to the other end.

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