JPH0684746U - Selective interruption overcurrent relay - Google Patents

Abstract

(57) [Summary] [Purpose] When an overcurrent relay has a short-circuit accident in the lower system, the circuit breaker in the upper system is not tripped, and only the circuit breaker at the accident occurrence point can be selectively cut. [Configuration] Upper and lower overcurrent relays 51R, 5
The limiter 12 for detecting that the instantaneous element 51H of 1F and the overcurrent element 51 and the current flowing in the lower system exceed the short-circuit current setting value of the instantaneous element 51H of the upper overcurrent relay 51R, and the limiter 12 of the limiter 12. A timer 13 that outputs a current I for a predetermined time to make the short-circuit current component of the instantaneous element 51H of the higher-order overcurrent relay 51R zero upon detection.
Provided on the input side of the instantaneous element 51H of the overcurrent relay 51R for the upper, compares the output signal of the timer 13 (output signal of the current transformer CT ₁₎ signal which detected the current flowing through the upper line (subtraction) And an adder 11 is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an overcurrent relay, and more particularly to a selective interruption overcurrent relay equipped with an accident point determination and interruption function and a host lock circuit.

[0002]

[Prior art]

 The current overcurrent relay is composed of 51 (overcurrent element) and 51H (instantaneous element) for one current transformer CT inserted in the power system as shown in Fig. 4, and the operation of 51, 51H. Will trip the corresponding breaker.

[0003]

[Problems to be solved by the device]

The overcurrent relay is used in a power system as shown in FIG. 5, for example. In FIG. 5, reference numeral 52R is an AC breaker inserted in the upper system, and the upper system is provided with a current transformer C T ₁ and an AC overcurrent relay 51R.

Reference numeral 52F ₁ is an AC circuit breaker inserted on the feeder 1 side of the lower system, and a current transformer CT ₂ and an AC overcurrent relay 51F ₁ are provided on the feeder 1 side. 52F ₂ is an AC breaker inserted on the feeder 2 side of the lower system, and a current transformer CT ₃ and an AC overcurrent relay 51F ₂ are provided on the feeder 2 side.

In the power system configured as described above, when a short circuit accident occurs at the point A of the feeder 1, the short circuit current is detected by 51F ₁ and 51R, but the operating time at the time of short circuit is 0.03sec-0. Since it is as short as 0.08 sec, 51F ₁ and 51R operate simultaneously, and it is difficult to cut off only the accident feeder 1. For this reason, 52R is opened by the operation of 51R and power cannot be fed to the healthy feeder 2 side.

The present invention has been made in view of the above points, and an object thereof is to provide a selective interruption overcurrent relay capable of selectively tripping a circuit breaker on the accident point side.

[0007]

[Means for Solving the Problems]

 In the overcurrent relay provided in the power system, the present invention is an instantaneous element and an overcurrent element of the upper overcurrent relay that monitors the current flowing in the upper system, and a lower overcurrent relay that monitors the current flowing in the lower system. The instantaneous element and the overcurrent element of the relay, and the detection unit that detects that the current flowing in the lower system exceeds the short-circuit current set value of the instantaneous element of the upper overcurrent relay for the upper circuit; and A current that is provided on the input side of the time element that outputs a signal for zeroing the short-circuit current of the instantaneous element of the host overcurrent relay for a predetermined time and the input of the instantaneous element of the host overcurrent relay that flows to the host system. It is characterized in that it is provided with an adder unit for adding the detected signal and the output signal of the timed element.

[0008]

[Action]

 First, the time at which the timing element outputs a signal is set to the time required to trip the circuit breaker of the lower system. If a short circuit accident occurs in the lower system, the instantaneous element and the overcurrent element of the lower overcurrent relay will operate, tripping the breaker inserted in the lower system.

When this short circuit accident is detected by the detection unit, the timing element outputs a signal for a predetermined time. Therefore, even if the current of the upper system increases due to the occurrence of the short-circuit accident, the current is canceled by the output signal of the time-limiting element in the adding section and becomes zero.

As a result, even if a short circuit accident occurs in the lower system as described above, the instantaneous element and the overcurrent element of the upper overcurrent relay do not operate for the predetermined time. Therefore, the circuit breaker of the lower system on the accident side trips within this fixed time, and the accident point is separated.Therefore, the circuit breaker of the upper system does not trip, and the other healthy system fails. There is no such thing.

[0011]

Embodiment An embodiment of the present invention will be described below with reference to the drawings. In the present invention, as shown in FIG. 1, a multi-circuit relay X is configured by arranging overcurrent relays for upper system and lower system in the same unit. In FIG. 1, CT ₁ is a current transformer that detects the current flowing in the upper system. The output current of the current transformer CT ₁ is input to the adder 11 provided on the input side of the instantaneous element (51H) of the upper overcurrent relay 51R and the overcurrent element (51) of the upper overcurrent relay 51R. To be done.

CT ₂ is a current transformer that detects a current flowing in a lower system. The output current of the current transformer CT ₂ is input to the instantaneous element 51H, the overcurrent element 51 and the limiter 12 of the lower overcurrent relay 51F. The limiter 12 outputs the current I as shown in FIG. 2 when the input current exceeds the short-circuit current setting value of the high-order overcurrent relay 51R.

Reference numeral 13 is a timer that outputs the current I 2 for a predetermined time after the current I is input, for example, 0.1 sec. The output current I of the timer 13 is compared (subtracted) with the output current of the current transformer CT _{1 in} the adder 11.

In the circuit configured as described above, first, the set time of the timer 13 is set to the time required to trip the circuit breaker of the lower system. When a short circuit accident occurs in the lower system, the instantaneous element 51H and the overcurrent element 51 of the lower overcurrent relay 51F operate to trip the breaker inserted in the lower system.

Due to this short circuit accident, a signal is output from the limiter 12, and the timer 13 outputs a signal (current I) for a predetermined time. Therefore, even if the current of the upper system input from the current transformer CT ₁ becomes large, the current is canceled by the output current I of the timer 13 in the adder 11 and becomes zero.

As a result, even if a short circuit accident occurs in the lower system as described above, the upper overcurrent relay 51R does not operate for the predetermined time. Therefore, by tripping the circuit breaker of the lower system of the accident side within this predetermined time, the accident point is separated, so that the circuit breaker of the upper system will not trip and the power failure of other healthy systems will not occur. Absent.

Although the multi-circuit relay X in the embodiment is for two units, the upper and lower units, the present invention is not limited to this, and two or more units for the lower unit are configured to obtain the same operation and effect as a multi-circuit. To be Further, the set time of the timer 13 is not limited to 0.1 sec, but can be arbitrarily set within a range of 0 to 0.1 sec, and is adjustable.

[0018]

[Effect of device]

 FIG. 3 shows a configuration in which short-circuit protection is performed on the upper system and the lower system composed of a plurality of feeders 1, 2, and 3. When a short-circuit accident occurs at point A of feeder 1 in FIG. 3, the AC breaker 52R trips in the conventional product, and it was not possible to completely prevent the power failure of all the feeders.

Further, there are two series of circuit breakers, 52R and 52F, but there may be three to five, and it was difficult to trip only the circuit breaker at the accident point. However, in the present invention, a multi-circuit relay including upper and lower circuits is used, and the input current of the lower relay is taken into the upper side so that the short circuit current input to the upper relay is zero. Therefore, the following excellent effects can be obtained.

(1) By selecting and tripping the circuit breaker at the accident point, the location of the accident is limited and the investigation for the accident is facilitated. (2) Distinguishing the fault point Since the upper circuit breaker does not trip due to disconnection, it is possible to prevent a total stoppage or a power failure of other circuits.

[Brief description of drawings]

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

FIG. 2 is a characteristic diagram showing input / output characteristics of a limiter used in an embodiment of the present invention.

FIG. 3 is a single wire connection diagram showing an example in which the present invention is applied to short-circuit protection of an upper system and a lower system composed of a plurality of feeders.

FIG. 4 is a configuration diagram showing an example of a conventional overcurrent relay.

FIG. 5 is a single wire connection diagram showing an example of performing short circuit protection of a power system using a conventional overcurrent relay.

[Explanation of symbols]

11 ... adder 12 ... Limiter 13 ... Timer 51 ... instantaneous elements CT ₁ to CT ₄ ... current transformer X ... multiple circuits relay overcurrent element 51H ... overcurrent relay of overcurrent relay

Claims (1)

[Scope of utility model registration request] 1. An overcurrent relay provided in a power system, wherein an instantaneous element and an overcurrent element of a higher-order overcurrent relay for monitoring a current flowing in a higher-order system and a lower-order overcurrent relay for monitoring a current flowing in a lower-order system. And a detection unit for detecting that the current flowing in the lower system exceeds the short-circuit current setting value of the instantaneous element of the higher-order overcurrent relay, and when detecting the detection unit, A timed element that outputs a signal for zeroing the short-circuit current component of the instantaneous element of the overcurrent relay for a predetermined time, and a current that is provided on the input side of the instantaneous element of the higher-order overcurrent relay and is detected in the upper system A selective interruption overcurrent relay, comprising: a signal and an adder for adding the output signal of the timed element.