JPH0836011A - Short circuit detecting checker - Google Patents

Abstract

PURPOSE:To easily and clearly detect the short circuit of a circuit to be tested with high safety. CONSTITUTION:Three-phase terminals 1a-1c to be detected, to which each phase of a three-phase test circuit is connected, and three phase power source terminals 2a-2c, to which each phase of a three phase low-voltage test power source is connected, are provided, and one end of contacts 3a-3c of each phase is connected to the power source terminals 1a-1c. This checker is provided with a three-phase breaker 3, which is closed at the time of detecting test, and series circuits 6a-6c of short circuit discriminating lamps (lighting elements) 4a-4c and current limiting impedance elements 5a-5c, which are provided between the other end of contacts 3a-3c of each phase of the breaker 3 and each terminal 1a-1c to be detected.

Description

Detailed Description of the Invention

[0001]

[Field of Industrial Application] The present invention relates to a short circuit detection checker for detecting a short circuit in a power receiving and transforming facility.

[0002]

2. Description of the Related Art Conventionally, the most important field tests performed in power plants, substations, demand facilities, etc. are a dielectric strength test and a test charging test (commercial voltage application test). This is because if these tests are successful, commercial operation will be started as it is.

Of these two tests, what is particularly troublesome is the dielectric strength test. In this test, each voltage part of the circuit under test, such as extra-high voltage and low voltage, is short-circuited by a short-circuit wire, and further, in terms of safety, etc. Considering this, the short-circuited part is grounded by the ground wire. By the way, it is necessary to remove the short-circuit wire and the ground wire used for the short circuit and the ground after the completion of the dielectric strength test.

That is, if the test charge test is performed without forgetting to remove these wires, not only the test equipment is damaged but also a serious accident is caused. Therefore, in order to detect the short-circuited part and confirm whether or not the short-circuit line and the ground line remain, conventionally, a low-voltage application test has been performed as a short-circuit detection test, and this test applies a low-voltage power supply directly to the circuit under test. The location of the short circuit is detected from the measurement results of voltage, current, etc.

[0005]

In the case of short-circuit detection by the conventional low voltage application test, the low voltage power source is directly applied to the circuit under test, which is dangerous and especially when the capacity of the low voltage power source is large. , The current flowing through the circuit under test becomes extremely large when there is a short-circuited point, which may cause damage to the test equipment connected to the circuit under test, damage to test personnel, etc., and sufficient safety cannot be ensured. There is a point.

Further, it is necessary to confirm a short circuit from the measurement results of various test instruments, which requires expensive various test instruments and cannot easily and clearly detect a short circuit. An object of the present invention is to provide a simple and inexpensive three-phase and single-phase short-circuit detection checker which is highly safe and can detect a short circuit easily and clearly.

[0007]

In order to achieve the above-mentioned object, the short-circuit detection checker according to the present invention according to claim 1 has three elements.
Three-phase detected terminals to which each phase of the circuit under test is connected, three-phase power supply terminals to which each phase of the three-phase low-voltage test power supply is connected, and power supplies of each phase to the power supply terminals of each phase Of the three-phase circuit breaker, which is connected during the detection test and the load side of each phase of the three-phase circuit breaker and the detected terminal of each phase for short-circuit determination and current limiting And an impedance element in series circuit.

A short circuit detection checker according to a second aspect of the present invention includes a detected terminal connected to a single-phase circuit under test,
Provided between the power supply terminal connected to the single-phase low-voltage test power supply, the power supply terminal connected to the power supply terminal, and the single-phase circuit breaker that is turned on during the detection test, and the load side of the single-phase circuit breaker and the detected terminal. And a series circuit of a lighting element for short circuit determination and an impedance element for current limiting.

[0009]

In the short-circuit detection checker of the present invention according to claim 1 configured as described above, each phase of the three-phase low-voltage test power supply is connected to the power supply terminal of each phase, and three are connected to the detected terminals of each phase. When each phase of the phase detection circuit is connected and the three-phase circuit breaker is turned on, when there is a two-phase or three-phase short circuit in the circuit under test, each lighting element for short-circuit determination is selected according to the short circuit. The short circuit of the three-phase detected circuit can be detected easily and clearly by turning on and off each lighting element.

Further, when there is a short-circuited portion in the three-phase circuit under test, the series circuit of the lighting element for short-circuit determination and the impedance element for current limiting determines the three-phase circuit under test when there is a short-circuited portion. The amount of energized current is suppressed, and even if the capacity of the 3-phase low-voltage test power supply is large, the current of the 3-phase circuit under test does not become excessive and safety and the like are secured.

Next, in the case of the short-circuit detection checker of the present invention according to claim 2, the detected terminal is connected to the single-phase circuit under test, and the single-phase power source terminal is connected to the single-phase low-voltage test power supply. When the phase breaker is turned on, the lighting element is turned on and off depending on whether the short circuit of the single phase test circuit is present or not, and the short circuit of the single phase test circuit is detected easily and clearly from this point or off.

Further, the series circuit of the lighting element for short-circuit determination and the impedance element for current limiting suppresses the amount of current flowing through the single-phase circuit under test when there is a short-circuited portion, and the capacity of the single-phase low-voltage test power supply is reduced. Even if it is large, the current of the single-phase circuit under test does not become excessive and safety is secured.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment will be described with reference to FIGS. In this embodiment, a single tester enables a low voltage application test for detecting a short circuit of a three-phase circuit under test and a transformation ratio test of a three-phase transformer.

FIG. 1 shows the circuit connection of the short-circuit detection checker, and FIGS. 2 and 3 show its shape. In these drawings, 1a, 1b and 1c are terminal connections for each phase of the circuit under test. Three-phase detected terminals 2a, 2b,
Reference numeral 2c is a three-phase power supply terminal to which each phase of the three-phase three-wire type 200V three-phase low-voltage test power supply is connected.

Reference numeral 3 is a three-phase circuit breaker in which one end on the load side of the contacts 3a, 3b, 3c of each phase is connected to each of the power supply terminals 2a to 2c, which is turned on during the detection test. Reference numerals 4a, 4b, and 4c are lighting elements (hereinafter referred to as lamps) for short-circuit determination for each phase, one end of which is connected to the other end on the power source side of the contacts 3a to 3c of each phase, and each is composed of an incandescent light bulb of 100V20W. 5
a, 5b and 5c are impedance elements for current limiting for each phase, one end of which is connected to the other ends of the lamps 4a to 4c, each consisting of a resistor of 300Ω20W, and the other ends of which are the detected terminals 1a to 1c of each phase. It is connected to the.

Reference numerals 6a, 6b and 6c denote lamps 4a to 4 of each phase.
c is a series circuit of impedance elements 5a to 5c, and 7 is a normally open three-phase main changeover switch for switching the test mode. One end of each phase contact 7a, 7b, 7c is a contact 3 of each phase.
It is connected to the other ends of a to 3c, and the other ends of the contacts 7a to 7c are connected to the detected terminals 1a to 1c of the respective phases. Reference numeral 8 denotes a normally closed three-phase auxiliary changeover switch which is interlocked with the main changeover switch 7. One end of each phase contact 8a, 8b, 8c is connected to the other end of each phase contact 7a to 7c.

Reference numeral 9 denotes a normally open three-phase operation switch for confirming lamp lighting, which is formed by a push button switch. One end of each phase contact 9a, 9b, 9c is connected to the other end of each phase contact 8a-8c. The other ends are connected to each other. 10
a, 10b, 10c are three-phase auxiliary terminals for transformer ratio test,
11 is a case body of the short-circuit detection checker 12, 13a, 13
Reference numerals b and 13c are receptacles for mounting the lamps 4a to 4c in the case body 11.

During the low voltage application test, the short circuit of the three-phase circuit under test is detected by the following procedure. (I) Connect each phase of the three-phase low-voltage test power supply to the power supply terminals 2a to 2c. (ii) For example, each phase of the three-phase circuit under test 14 shown in FIG. 4 is connected to the detected terminals 1a to 1c. This circuit under test 14 is a transformer 1 of 77 / 3.3KV, 7500KVA of a substation.
On the secondary side (low-voltage side) of 5, 3.3 KV three-phase bus 16
It is constructed by connecting a, 16b and 16c. Also,
The transformer 15 has a star (Y) connection on the primary side (high voltage side) and a delta (Δ) connection on the secondary side.

By connecting each phase on the primary side of the transformer 15 to the terminals to be detected 1a to 1c, the electric line including the transformer 15 from the extra high voltage to the normal height of the substation becomes a detection target. .

(Iii) To carry out the detection test, the three-phase circuit breaker 3 is turned on. At this time, since the transformer 15 has a Y-Δ connection, the condition is that the phase rotation of the power supply is positive.
All of the lamps 4a to 4c are lit in a three-phase short circuit, one corresponding lamp is lit in a two-phase short circuit, and all lamps are extinguished when there is no short circuit part.

That is, as a result of an experiment in which the R, S, and T three-phase buses 16a to 16c on the secondary side of the Y-Δ connected transformer 15 are short-circuited, the phase rotation of the three-phase low-voltage test power supply is positive. At this time, the combination of the short-circuited phase and the lit lamp is as shown in the following Table 1, and in this Table 1, L ₁ , L ₂ , L ₃
Indicates lamps 4a, 4b and 4c.

[0022]

[Table 1]

Therefore, the short circuit of the three-phase circuit under test 14 can be easily and clearly detected from the turning on and off of each of the lamps 4a to 4c.

Moreover, since the three-phase low-voltage test power source is applied to the circuit under test 14 through the series circuits 6a to 6c of each phase, the impedance element 5a of the series circuits 6a to 6c is present even if there is a short-circuited portion. By 5c, an increase in the amount of current flowing through the circuit under test is suppressed, and safety and the like are improved.

If the transformer 15 is a Δ-Δ connection,
The lamps 4a to 4c are all turned on when a three-phase short circuit occurs, and 2
At the time of phase short circuit, two lights corresponding to the two short-circuited lights,
If there is no short-circuited portion, all lights are kept turned off, and in this case as well, short-circuit detection can be performed by turning on and off the lamps 4a to 4c.

(Iv) The operation switch 9 is turned on to short-circuit the terminals 1a to 1c to be detected. Due to this short circuit, the same state as the three-phase short circuit is obtained, and it is confirmed that the lamps 4a to 4c are lit, and from this point, the lamps 4a to 4c are judged to be good or defective. Then, this judgment confirms whether the short-circuit detection result of (iii) above is correct or incorrect, and further improves the reliability of short-circuit detection.

Next, the transformer ratio test of the three-phase transformer 15 is performed in the following procedure. (I) Connect each phase of the three-phase low-voltage test power supply to the power supply terminals 2a to 2c. (ii) Connect each phase terminal on the primary side of the transformer 15 to the detected terminals 1a to 1c.

(Iii) The transformer 1 is attached to the auxiliary terminals 10a to 10c.
Connect each phase terminal on the secondary side of No. 5. (iv) The main selector switch 7 is turned on (O)
N), the main selector switch 7 is closed and the sub selector switch 8 is opened.

At this time, each contact 7a of the main changeover switch 7
By closing 7c to 7c, the series circuits 6a to 6c of the respective phases are short-circuited, and the detected terminals 1a to 1c are the contacts 3a of the three-phase circuit breaker 3.
It is directly connected to the other end of 3c. Further, the operation switch 9 is disconnected by opening the contacts 8a to 8c of the sub-switch 8.

(V) In order to carry out the transformer ratio test, the three-phase circuit breaker 3 is turned on, and the three-phase low-voltage test power supply is applied to the primary side of the transformer 15. (vi) A voltmeter is connected to the detected terminals 1a to 1c, and the primary voltage of the transformer 15 is measured.

(Vii) A voltmeter is connected to the auxiliary terminals 10a to 10c to measure the secondary voltage of the transformer 15. (viii) Calculate the transformation ratio of each phase of the transformer 15 from the formula of primary voltage / secondary voltage = transformation ratio based on the measurement result of the primary voltage and the secondary voltage of each phase of the transformer 15.

Therefore, in this embodiment, a low voltage application test for detecting a short circuit of the three-phase circuit under test 14 and a transformation ratio test of the three-phase transformer 15 can be performed using one tester 12.

The checker 12 is formed by the three-phase circuit breaker 3, the lamps 4a to 4c, the impedance elements 5a to 5c, the switches 7, 8 and 9 and the like into a structure having a small number of parts, simple, inexpensive and hard to break down. It

Even if the lamps 4a to 4c are burnt out, they are incandescent lamps that are easily available.
The checker 12 can be easily replaced, and since the circuit configuration is simple, inspection and repair can be performed easily, and maintenance and management of the checker 12 are extremely easy.

By the way, if the transformer ratio test is unnecessary,
Main and sub selector switches 7, 8 and auxiliary terminals 10a to 10c
Can be omitted, and it can be made simpler and cheaper. Further, if it is not necessary to confirm the lighting of the lamps 4a to 4c, the operation switch 9 can be omitted, which further simplifies and reduces the cost.
Further, the lamps 4a to 4c may be other than the incandescent light bulb, and the impedance elements 5a to 5c for current limiting may be various inductance elements, reactance elements, or the like.

Next, a case where the present invention is applied to detection of a short circuit in a single-phase circuit under test will be described. In this case, the short-circuit detection checker has a configuration corresponding to at least one phase in FIG. 1, for example.

That is, in order to perform a low voltage application test for short circuit detection, the short circuit detection checker is, for example, the terminal 1 to be detected in FIG.
A contact of a single-phase circuit breaker corresponding to the contact 3a and a series circuit of the lamp 4a and the impedance element 5a are provided in series between a and the power supply terminal 2a.

The detected terminal 1a is connected to the non-grounded line of the single-phase detected circuit, and the power supply terminal 2a is connected to the non-grounded terminal portion of the single-phase low-voltage test power supply.

When judging whether the lamp 4a is good or bad and performing the transformer ratio test of the single-phase transformer of the single-phase circuit under test corresponding to the transformer 15, the operation switch 9 and the changeover switch 7 of FIG. , Single-phase operation switch corresponding to 8 and main,
A sub switch and an auxiliary terminal 10a are also provided.

Further, from a practical point of view, the ground line of the single-phase circuit under test, the ground terminals on the detected side and the power supply side, which are connected to the ground end of the single-phase low-voltage test power supply, are also provided. Although only short-circuiting may be performed, a contact on the ground side of the single-phase circuit breaker that interlocks with the contact between the terminals 1a and 2a is provided between the two ground terminals.

When the single-phase circuit under test and the single-phase low-voltage test power supply are connected and the single-phase circuit breaker is turned on, the lamp 4a is turned on and off depending on whether the single-phase circuit under test is short-circuited or not. However, at this point, a short circuit is detected by turning off the light.

Also, by turning on the operation switch and the main / sub switching switch, the lighting confirmation of the lamp 4a and the transformer ratio test can be performed in the same manner as in FIG. Therefore, the same test as in the first embodiment can be performed on the single-phase test circuit and the single-phase transformer.

By the way, as in the case of the first embodiment, the operation switch, the main / sub switching switch, and the auxiliary terminal 10a may be omitted, and the lamp 4a may be other than the incandescent lamp.
The impedance element 5a for current limiting may be an inductance element or a reactance element.

Further, instead of using the checker for single phase, two phases of the checker for three phases in FIG. 1 are used, and for example, the detected terminals 1a and 1b in FIG. Ground line, connected to the ground line, power terminals 2a, 2b
May be connected to the non-grounded end and the grounded end of the single-phase low-voltage power supply, and in this case, one checker can
Phase and single phase tests can be performed.

[0045]

Since the present invention is configured as described above, it has the following effects. First, in the case of the short circuit test checker according to claim 1, each phase of the detected circuit is connected to the detected terminals 1a to 1c of each phase, and each of the power supply terminals 2a to 2c of each phase is connected to each of the three-phase low-voltage test power supplies. Connect the phases 3
When the phase breaker 3 is turned on, when there is a two-phase or three-phase short circuit in the three-phase circuit under test, the respective lamps 4a to 4c for short-circuit determination are selectively turned on according to the short circuit, and each lamp 4a. ~ 4
It is possible to easily and clearly detect a short circuit in the three-phase circuit under test from the point c and the turning off.

Moreover, when there is a short circuit in the circuit under test, a series circuit 6a of the lamps 4a to 4c for judging the short circuit of each phase and the impedance elements 5a to 5c for current limiting is provided.
By ~ 6c, the amount of current flowing through the three-phase circuit under test is suppressed,
Even if the low-voltage test power supply has a large capacity, the current of the circuit under test does not become excessive, and safety and the like can be secured.

Therefore, the three-phase circuit breaker 3 and the lamps 4a ...
The short circuit of the three-phase circuit under test can be detected easily and clearly and with high safety by using a simple and inexpensive structure with a small number of parts including 4c and impedance elements 5a to 5c.

Further, in the case of the short circuit test checker according to the second aspect, it is possible to simply and clearly detect the short circuit of the single-phase circuit under test, and further, the lamp (lighting element) and the impedance element for current limiting are connected in series. The circuit suppresses the current of the circuit under test, and the same effect as in the case of claim 1 can be obtained in the test of the circuit under test.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a plan view of an embodiment of the present invention.

FIG. 3 is a cut front view of an embodiment of the present invention.

FIG. 4 is an explanatory diagram of a test of one example of the present invention.

[Explanation of symbols]

 1a to 1c Detected terminal 2a to 2c Power supply terminal 3 Three-phase circuit breaker 3a to 3c Contact point of three-phase circuit breaker 3 4a to 4c Lamp for short circuit determination 5a to 5c Resistance for current limiting

[Procedure amendment]

[Submission date] November 29, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

[0022]

[Table 1]

Claims (2)

[Claims] 1. A three-phase detected terminal connected to each phase of a three-phase circuit under test, a three-phase power supply terminal connected to each phase of a three-phase low-voltage test power supply, and a power supply terminal of each phase The power supply side of each phase is connected to the three-phase circuit breaker that is turned on during the detection test, and the short-circuit determination provided between the load side of each phase of the three-phase circuit breaker and the detected terminal of each phase. Short-circuit detection checker comprising a series circuit of a lighting element for lighting and an impedance element for current limiting. 2. A detected terminal connected to a single-phase circuit under test, a power supply terminal connected to a single-phase low-voltage test power supply, and a power supply side connected to the power supply terminal, and a single-phase cutoff that is made during a detection test. Circuit, a short circuit detection comprising a series circuit of a lighting element for short circuit determination and an impedance element for current limiting provided between the load side of the single-phase circuit breaker and the detected terminal checker.