JPS602020A - Testing circuit of protecting relay - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Background of the Invention] Protection succession'? [i: As shown in Figure 1, the test calibration terminal of the instrument panel is connected between the current transformer 2 and the protective relay 30, and when testing the protective relay panel, the test calibration terminal is connected to the current transformer secondary circuit and the protective relay. This is used to connect the test power supply to the here,
What if you are using a differential current type protection relay that connects multiple current transformers such as a busbar protection relay or a transformer protection relay to one 1L protection relay? show.

Generally, in a differential current protection relay, the differential current on the secondary side of the current transformer is zero during normal times, but when an internal failure occurs, a differential current is generated and the protective relay operates. However, during the test, one of the multiple current transformer secondary circuits
By short-circuiting the test calibration terminals at the ends, a differential current may occur and the protective relay may operate. This is because, depending on the magnitude of the load'a current during normal operation, the secondary circuit of the current transformer may be short-circuited, causing a differential current that can operate the protective relay to flow. In the protective relay panel, in order to prevent the circuit breaker 4 from being cut off due to the operation of the protective relay, a lock terminal 6 is connected to each circuit, and the calibration terminal 1 is connected to the current transformer 2 during testing. Next circuit? Before short-circuiting, the breaker tripping circuit is locked by the part that opens the lock terminal 5.

However, if the order of the above operations is incorrect during the test, there is a problem in that the protection relay is activated and the circuit breaker is disconnected as soon as the secondary circuit of the current transformer is short-circuited.

[Purpose of the invention]

The object of the present invention is to operate the current transformer secondary circuit all through the calibration terminal, and at the same time lock the breaker row disconnection circuit.
6 all provided.

[Embodiments of the invention]

FIG. 2 shows an embodiment of the present invention.

An example in which the present invention is applied to an all-bus protection relay panel is shown below.

In the disconnection protection method, current transformers 2 of all lines drawn out from the bus are connected to the bus protection relay 3 via the calibration terminal 1.
Connect to. When a failure occurs on the busbar, the busbar protection relay operates, and the auxiliary relay 5 operates, and its contacts are connected to the trip coils of the circuit breakers 4 of each line, so all the circuit breakers connected to the faulty busbar are disconnected. Remove the device.

In the present invention, the lock terminal 6 is connected to the excitation circuit of the auxiliary relay 5. This lock terminal is the calibration terminal 1 and CT secondary +
It is possible to automatically open the tripping circuit before a short circuit occurs, and the lock terminals of all lines are connected in series to the auxiliary relay 5. As a calibration terminal having this function, "Japanese Unexamined Patent Publication No. 57-36529 1'lJ, Panel Calibration Terminal" can be used.

The operation during the test will be explained below with reference to FIG. 3.

FIG. 3 shows details of one line in FIG. 2. A test plug in which the test power supply 7 and the current transformer secondary circuit are short-circuited 8 to the calibration terminal 1 in order to test the protective relay 3? When inserted, the locking terminal 6 is opened before the CT secondary short circuit is made.

The lock terminals 6 of all lines are connected in series, and the protective relay 3
It is connected to the auxiliary relay 5 through the contact Kl. Therefore, when a test plug is inserted into the calibration terminal for testing on a certain line, the secondary circuit of the current transformer is short-circuited, a differential current is generated in the protective relay 3, and even if the relay operates, Since the locking terminal 6 is already open and the auxiliary relay 5 is not excited, it is possible to prevent the breaker from being accidentally tripped.

In the embodiment, an example of bus bar protection is shown, but a similar circuit configuration can be applied to transformer protection and power generator protection that operate with differential current.

〔Effect of the invention〕

According to the present invention, during a test, the trip circuits of all circuit breakers related to the protective relay are automatically opened before a secondary short circuit occurs in the current transformer. can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of the prior art, FIG. 2 is a circuit diagram of an embodiment of the present invention, and FIG. 3 is a circuit diagram of one line in FIG. -α Figure 1 Country 2

Claims (1)

[Claims] 1. In a test circuit for a protective relay that operates with a differential current, a current transformer secondary circuit calibration terminal having a lock terminal type in a tripping circuit is used, and this calibration terminal is used to detect the current transformer secondary circuit. A test circuit for a protective relay, characterized by providing a means for automatically locking the breaker before the circuit is short-circuited.