JP2006194794A - Short-circuit detecting device of terminal device wiring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately discriminate short-circuit with inexpensive circuitry without using complicated and highly accurate circuitry. <P>SOLUTION: This short-circuit detecting device of the terminal device wiring comprises the terminal device wiring where at least one terminal device is connected in parallel; a driving power source for supplying voltage to the terminal device wiring; a load connected in series between the driving power source and the terminal device wiring; and a short-circuiting detecting section for determining the short-circuiting by detecting the size level of the voltage produced between both ends of the load when the voltage is supplied to the terminal device wiring. The internal resistance of the load increases when the current increases. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a short-circuit detection device for terminal equipment wiring that detects a magnitude level of a voltage generated between both ends of a load connected in series between a driving power source and terminal equipment wiring to determine a short circuit.

  Conventionally, for example, in a fire alarm system, when a fire detector installed at an appropriate place in a building is triggered, a fire alarm is output at the fire receiver, and as an example of a terminal device corresponding to the fire detector, The district bell is ringing. For this reason, the drive power is supplied to the district acoustic wiring as an example of the terminal equipment wiring, and the power is supplied to the connected district bells all at once. In addition to the device disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-339572 (Patent Document 1), various devices are conventionally known as the short circuit detection device for the district acoustic wiring.

  FIG. 2 shows one conventional example of a short circuit detection device for district acoustic wiring. For example, the district acoustic wiring L in which two district bells B are connected in parallel is connected to the district acoustic terminals Bn and Bc of the fire receiver RE. The fire receiver RE has a fixed load R1, a fuse F1, a backflow prevention diode D1, a drive power source E1 connected in series to the terminal Bn, and a relay contact RY1 (normally open) whose other end is grounded. Connected to Bc, the voltage detection unit 20 is connected between both ends of the fixed load R1, and the signal processing unit 10 is provided. The district bell B has a rated current of 1A, for example, and the drive power supply E1 has a rated current set as appropriate depending on the number of district bells B connected. Moreover, the voltage detection part 20 and the signal processing part 10 comprise the short circuit detection part T1.

When the signal processing unit 10 receives a fire signal from a fire detector (not shown), the signal processing unit 10 closes the relay contact RY1. Then, the district acoustic wiring L is supplied with a driving voltage from the driving power source E1 through the terminals Bn and Bc, and the district bell B is driven. Further, the voltage detection unit 20 detects the voltage level V1 generated between both ends of the fixed load R1 at that time, and the signal processing unit 10 collects the voltage level V1 and compares it with the short-circuit level VT stored in the internal memory. To determine whether it is normal or short-circuited.
JP 2001-184571 A

  Conventionally, in order to drive the district bell B normally, it is necessary to reduce the voltage drop of the drive voltage in the district acoustic wiring L. Therefore, the fixed load R1 needs to have a very small resistance value. For example, if the resistance value of the fixed load R1 is 0.1Ω, the voltage level V1 when driving the district bell B is 0.2V. Further, the short circuit level VT is 0.3 V as a short circuit when it is determined that a short circuit occurs when a current of 3 A flows through the district acoustic wiring L. The short-circuit detection unit T1 must accurately distinguish between 0.2V of the voltage level V1 at the time of driving the district bell B and the short-circuit level VT. That is, the short-circuit detection unit T1 detects a minute voltage level V1 generated between both ends of the fixed load R1, and compares the voltage level V1 with the short-circuit level VT to determine the occurrence of a short-circuit. In order to detect an accurate voltage level V1 and accurately determine the occurrence of a short circuit, a complicated and highly accurate circuit configuration must be provided.

  The present invention has been made to solve the above-described problem, and provides a short circuit detection device for terminal equipment wiring that can accurately determine a short circuit with an inexpensive circuit configuration without using a complicated and highly accurate circuit configuration. The purpose is to provide.

  The present invention includes a terminal device wiring in which at least one terminal device is connected in parallel, a driving power source that supplies a voltage to the terminal device wiring, and a load that is connected in series between the driving power source and the terminal device wiring. When a voltage is supplied to the terminal device wiring, a short circuit detection of the terminal device wiring having a short circuit detection unit that detects a magnitude level of the voltage generated at both ends of the load at that time and determines a short circuit The apparatus is characterized in that the load is a load whose internal resistance increases as the current increases. The load is a polyswitch.

  The present invention provides a load connected in series between the drive power supply and the terminal equipment wiring, and when a voltage is supplied to the terminal equipment wiring as a load that increases the internal resistance when the current increases, for example, a polyswitch, At that time, the short circuit detector detects the magnitude level of the voltage generated between both ends of the load and determines whether it is normal or short-circuited. There is an effect that a short circuit can be accurately discriminated by the configuration. In addition, the short-circuit current can be limited to be slightly smaller than in the past, and for example, the relay contact capacity can be made smaller and the wiring pattern can be made thinner than in the past.

  FIG. 1 is a diagram showing a district acoustic wiring short-circuit detection device according to an embodiment of the present invention. The difference from FIG. 2 is that a polyswitch R2 is provided instead of a fixed resistor R1.

  That is, for example, the district acoustic wiring L in which two district bells B are connected in parallel is connected to the district acoustic terminals Bn and Bc of the fire receiver RE. The fire receiver RE has a poly switch R2, a fuse F1, a backflow prevention diode D1, a drive power source E1 connected in series to the terminal Bn, and a relay contact RY1 (normally open) whose other end is grounded. Connected to Bc, a voltage detection unit 20 is connected between both ends of the polyswitch R2, and a signal processing unit 10 is provided. The district bell B has a rated current of 1A, for example, and the drive power supply E1 has a rated current set as appropriate depending on the number of district bells B connected. Moreover, the voltage detection part 20 and the signal processing part 10 comprise the short circuit detection part T2.

  The polyswitch R2 is a polymer-based PCT thermistor, which is a load whose internal resistance increases as the current increases. When heated by overcurrent or heating, the internal temperature of the element increases and the resistance value increases rapidly. . For example, it operates at twice the rated current, and its resistance value reaches from the fourth power to the sixth power. For example, the polyswitch R2 of this embodiment has a resistance value of 0.1Ω in a normal state, and the resistance value rapidly increases when a current of 3A that is determined to be short-circuited flows. Therefore, the voltage level V1 generated between both ends of the polyswitch R2 is a minute voltage level V1 (for example, 0.2V) similar to that in the past when the district bell B is driven. A voltage larger than the minute voltage level V1 generated when the short circuit occurs is generated. For this reason, the short-circuit level VT can be set to a voltage level that is much higher than the conventional level (for example, 0.3 V). As a result, the short-circuit detection unit T2 can have a cheaper circuit configuration than the conventional complicated circuit configuration with high accuracy, and can accurately determine the occurrence of a short circuit.

  Further, since the internal resistance of the polyswitch R2 increases, the short-circuit current can be limited to a smaller amount than in the prior art. Therefore, the contact capacity of the relay contact RY1 can be reduced and the wiring pattern can be made thinner than before. Further, when an external power supply having a voltage value higher than that of the drive power supply E1 is short-circuited to the district acoustic wiring L, the rated current of the backflow prevention diode D1 that protects the drive power supply E1 can be reduced.

  The polyswitch R2 can also serve as the fuse F1 because the resistance value increases rapidly due to overcurrent, and the fuse F1 can be eliminated. At this time, it is not necessary to replace the polyswitch R2 as a fuse as an overcurrent prevention circuit, and by turning off the power of the fire receiver RE, the temperature is lowered and the resistance value is restored.

  When the signal processing unit 10 receives a fire signal from a fire detector (not shown), the signal processing unit 10 closes the relay contact RY1. Then, the district acoustic wiring L is supplied with a driving voltage from the driving power source E1 through the terminals Bn and Bc, and the district bell B is driven. Further, the voltage detection unit 20 detects the voltage level V1 generated between both ends of the polyswitch R2 at that time, and the signal processing unit 10 collects the voltage level V1 and compares it with the short-circuit level VT stored in the internal memory. Then, the wiring state of the district acoustic wiring L is determined. That is, if the voltage level V1 is equal to or higher than the short-circuit level VT, it is determined that the circuit is short-circuited. If the voltage level V1 is 0V, it is determined that the circuit is disconnected. If it is determined that the connection is broken or short-circuited, an abnormality is notified from a speaker (not shown).

  In the present embodiment, when the drive voltage is supplied to the district acoustic wiring L, the voltage detection unit 20 detects the voltage level and determines the short circuit. Thus, it is possible to determine whether or not a short circuit is always present in the same manner as the drive voltage.

  For this purpose, a terminal resistor is provided at the end of the district acoustic wiring L, and a diode is arranged on the district bell B so that current flows only in the ringing direction, and the monitoring voltage limited from the drive power supply E1 is connected to the terminal Bc side. To the terminal Bn side. And when ringing the district bell B, a switch circuit for switching the drive power source E1 from the terminal Bn side to the terminal Bc side may be provided.

  In the present embodiment, the terminal device is described as a district bell, but it may be a control device such as a fire detector or a fire door, and the terminal device wiring is described as a district acoustic wiring. It is good.

  The present invention includes a district acoustic wiring L as terminal equipment wiring in which district bells B as at least one terminal equipment are connected in parallel, a drive power supply E1 for supplying a voltage to the district acoustic wiring L, the drive power supply E1, A load connected in series with the district acoustic wiring L and when a voltage is supplied to the district acoustic wiring L, the magnitude level of the voltage generated at both ends of the load is detected at that time, and a short circuit is detected. A short-circuit detecting device for terminal equipment wiring comprising a voltage detecting unit 20 and a signal processing unit 10 as a short-circuit detecting unit T2 for determining the load, wherein the load is a poly-state as a load whose internal resistance increases as the current increases. Since the switch R2 is used, there is an effect that a short circuit can be accurately detected with an inexpensive circuit configuration without using a complicated and highly accurate circuit configuration. In addition, the short-circuit current can be limited to be slightly smaller than in the past, and for example, it is possible to simplify the contact capacity of the relay contact RY and the wiring pattern to be thinner than in the past.

It is a circuit diagram which shows the short circuit detection apparatus of the district acoustic wiring which is one Example of this invention. It is a circuit diagram which shows the short circuit detection apparatus of the conventional district acoustic wiring.

Explanation of symbols

B district bell (terminal equipment)
L district acoustic wiring (terminal equipment wiring)
E1 Drive power supply R2 Load (Poly switch)
T2 Short-circuit detection unit RE Fire receiver 10 Signal processing unit 20 Voltage detection unit

Claims (2)

Terminal equipment wiring in which at least one terminal equipment is connected in parallel;
A drive power supply for supplying voltage to the terminal equipment wiring;
A load connected in series between the drive power supply and the terminal equipment wiring;
When a voltage is supplied to the terminal equipment wiring, a short-circuit detection device for the terminal equipment wiring, which includes a short-circuit detection unit that detects a magnitude level of the voltage generated at both ends of the load at that time and determines a short-circuit. Because
The load is a load whose internal resistance increases as the current increases. 2. The short circuit detection device for terminal equipment wiring according to claim 1, wherein the load is a polyswitch.

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