JPH0142447B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a disconnection detection circuit for a circuit breaker tripping circuit.

[Conventional technology]

As a disconnection detection circuit for a shingle breaker tripping circuit, for example, there is known a circuit disclosed in Japanese Utility Model Application No. 166553/1983, which monitors the abnormal state of the shingle breaker regardless of whether the shunt breaker is opened or closed. An overview of this known example is as follows.

The figure shows one embodiment of the present invention. First, the conventional circuit part in this figure will be explained. The tripping circuit of the shield breaker 10 is a tripping command connected between the positive and negative power supplies PT and NT. This is a series circuit consisting of a contact 12, a pallet switch 10a that closes when the breaker is closed, and a tripping coil 11. Of these, the pallet switch 10a and the tripping coil 11 are installed near the breaker 10, and the tripping command contact 12
Since it is installed in the operation room, a cable T must be laid and connected, and the cable T can be several hundred meters long. Needless to say, the tripping circuit is the final stage of the protective relay system, and it is necessary to ensure the correct operating state of the tripping command contact 12 and the disconnector 10.
It must be something that can be communicated to the public. For this reason, it is necessary to detect the disconnection of the cable T and the tripping coil 11, and in the above-mentioned known example, a weak current (the tripping coil 11 is of a DC operating type) is generated to the extent that the tripping coil 11 cannot operate. Therefore, an AC signal may be applied.) to detect disconnection.

In other words, a constant monitoring method is adopted as a method for detecting disconnection, and a series circuit consisting of a current limiter such as a resistor (7-1) and a detector such as a current relay (8-1) is tripped at the command contact 12. A weak current limited by the resistor (7-1) is caused to flow through the tripping coil 11. In this case, if there is a disconnection in the tripping circuit on the side of the insulation breaker 10, a weak current will not flow and the current relay (8-1) will return and open its contact 8a, so the time-limited return relay 9 will return to operation. Then, the normally closed contact 9b is closed and an alarm is displayed to indicate the occurrence of disconnection in the tripping circuit on the disconnector side. This monitoring method makes it possible to check the health of the tripping circuit.

However, this only holds true when the breaker 10 is closed (when the pallet switch 10a is closed), and does not hold when the breaker is open. In other words, opening the palette switch 10a is equivalent to disconnection of the tripping circuit, and in the case of constant monitoring, an alarm will be issued to indicate an abnormality in the tripping circuit. Therefore,
In a known example, in order to solve this problem, a series circuit consisting of a palette switch 10b, a detector such as a current relay (8-2), and a current limiter such as a resistor (7-2) is connected in parallel with the palette switch 10a. did. In this figure, 1 is an inspection/display section, 6 is a monitoring/display section, and P and N are display power supplies. The operation of this conventional wire breakage detection circuit will be described. Since the palette switch 10b is open when the shroud breaker 10 is closed, the circuit configuration and operation are as described above, so a description thereof will be omitted. If an accident occurs in the power system in this state, the trip command contact 12 closes, and the tripping coil 11 of the shield breaker 10 is energized via the cable T and the pallet switch 10a, and when the shield breaker 10 is opened, the pallet switch 10a is activated. open, and 10b closes. From this point on, PT-(7-1)-(8-1)-T-1
-(7-2)-(8-2)-K-10b-11 A minute current flows through the NT circuit to perform monitoring. (8
-1) and (8-2) are double-coil current relays, which close the contact 8a no matter which coil is excited. Transiently PT-12-T-I-(7-2)
-(8-2)-K-10b-11-NT also flows, but in this case as well, it is a very small current that is limited by the resistor (7-2).

[Problem that the invention seeks to solve]

According to the above-mentioned known example, the tripping circuit can be constantly monitored regardless of whether the breaker is open or closed. However, in this known example, even if a disconnection occurs in the constant monitoring circuit itself, the same display output is given when the tripping circuit is disconnected, and when the constant monitoring circuit outputs, the same display output is given. There was a problem in that it was not possible to determine whether it was an abnormality in the original tripping circuit or an abnormality in the constant monitoring circuit (the tripping circuit itself was normal).

Therefore, it is an object of the present invention to provide a disconnection detection circuit for a circuit breaker tripping circuit that can distinguish between an abnormality in the tripping circuit and an abnormality in the constant monitoring circuit.

[Means for solving problems]

A first circuit containing a shinoda breaker tripping command contact 12 is installed in the operation room, and a first circuit that closes when the shinoda breaker is closed is installed at the site where the shinoda breaker is installed. A second circuit including a series circuit with contact 10a of
The first and second circuits are connected in series with a cable T, and a first detector 8 is connected in parallel to the first circuit.
-1 and the first current limiter 7-1 are connected, and the second contact 10b and the second current limiter are connected in parallel to the first contact 10a and are closed when the breaker opens. A fifth circuit consisting of a second detector 2, a third current limiter 3 and a first inspection contact 4-1 is connected in parallel to the first circuit.
A second inspection contact 4-2 is provided in parallel with the second current limiter 7-2.

[Effect]

By appropriately closing the inspection contacts, when the shield breaker is closed, the fifth circuit - cable - first contact -
When the circuit of the tripping coil is open, the circuit consisting of the fifth circuit, the cable, the second inspection contact, and the tripping coil is energized, and an abnormality can be detected. Also, when the inspection contact is closed when the detector of the third circuit (normal monitoring circuit) outputs an output and determines that there is a disconnection, the presence or absence of the detector output of the fifth circuit (inspection circuit) Correspondingly, it is possible to distinguish between faults in the trip circuit and faults in the monitoring circuit.

〔Example〕

In the present invention, a check circuit 1 is added to a conventionally known circuit. In other words, a series circuit of the detector 8, the current limiter 3, and the inspection contact 4-1 is provided in parallel to the trip command contact 12, and a series circuit of the current limiter 7-2 and the detector 8-2 is connected to the trip command contact 12. An inspection contact 4-2 is provided in parallel. However, when inspection is performed, inspection current flows through the next circuit by closing inspection contacts 4-1 and 4-2.

When the shield breaker is opened (when the pallet switch 10b is closed) PT-2-3-(4-1)-T-I(4-2)-K
-10b-11-NT.

When the shield breaker is closed (when the pallet switch 10a is closed) PT-2-3-(4-1)-T10a-11-
N.T.

If the detector 2 (for example, a lamp) lights up during such inspection, it can be determined that the circuit is connected and healthy, and if it does not light up, it can be determined that the trip circuit is disconnected. Incidentally, when the constant monitoring circuit 6 is giving an output, it is not possible to immediately trip this and determine that the circuit is disconnected. That is, PT-(7-1)-(8-1)
-T-10a-11-NT, or PT-(7-1)
-(8-1)-T-I-(7-2)-(8-2)-K-
If there is a break in a part of 10b-11-NT, the constant monitoring circuit 6 can output, and the tripping circuit (cable T, pallet switch 10a, tripping coil) and the constant monitoring circuit (current limiter 7-1, 7-
2. Even if a disconnection occurs in any of the detectors 8-2, 8-2, cables I and K, and palette switch 10b), the signal is output. By performing inspection at the output of the constant monitoring circuit 6, the disconnected part can be identified.If the detector 2 does not light up, it is a disconnection in the tripping circuit, and if it lights up, it can be said that it is a disconnection in the constant monitoring circuit. .

Note that (8-1) and (8-2) are double-coil current relays, which close the contact 8a no matter which coil is excited. Temporarily PT-12-T-
I-(7-2)-(8-2)-K-10b-11-
It also flows to NT, but in this case there is also resistance (7-2)
It becomes a minute current limited by . In order to suppress overcurrent caused by this trip command contact 12, it is sufficient to connect the palette switch 10b and the resistor (7-2) in parallel to the palette switch 10a, and the double coil (8-2) is used to prevent the circuit breaker from opening. This is to keep the ampere-turn of the relay coil constant regardless of whether the circuit breaker is open or closed, since the monitored current when the circuit breaker is closed is half of that when the circuit breaker is closed.

〔effect〕

According to the present invention, by using an inspection circuit in addition to the constant monitoring circuit, it is possible to identify the disconnection location.
And it can be made into a highly reliable device.

[Brief explanation of drawings]

The figure shows one embodiment of the invention. I, T, K...Cable, 10...Shiya disconnector,
10a, 10b... Palette switch, 11...
Tripping coil, 3, 7-1, 7-2... Current limiter, 2, 8-1, 8-2... Detector, PT, NT
...Power supply, 12...Tripping command contact, 4-1, 4
-2...Contact for inspection.

Claims (1)

[Claims] 1 Install the first circuit containing the tripping command contact for the breaker in the operation room, and the first circuit that closes when the breaker closes as the trip coil for the breaker at the site where the breaker is installed. In a disconnection detection circuit for a disconnection tripping circuit comprising a second circuit including a series circuit with a contact and connecting the first and second circuits with a cable, the first detection circuit is connected in parallel to the first circuit. a fourth circuit comprising a second current limiter and a second contact which is connected in parallel to the first contact and closes when the circuit breaker is opened; A fifth circuit consisting of a second detector, a third current limiter and a first inspection contact is connected in parallel with the first circuit, and a fifth circuit is connected in parallel with the second current limiter. A disconnection detection circuit for a breaker tripping circuit, characterized in that a second inspection contact is provided at the breaker.