SU1711285A1 - Device for protection of three-phase load against short- circuit - Google Patents

Abstract

The invention relates to electrical engineering and is intended for use in relay protection circuits for electrical installations of short-circuit outflows. The purpose of the invention is to increase the reliability and speed of protection by combining the functions of the drive of the closing contacts and the sensor of the emergency current of the power line of the consumer. When the automatic switch 1 is turned on and the consumer 2 is in normal operation mode, the electrodynamic forces between the fixed coils 6 and the moving coils 8 generated by the currents do not exceed the forces of the springs 7. The closing contacts of groups 3, 4, 5 are open and all current flows through the consumer 2. At short circuit, when the current in any of the phases exceeds the preset setpoint of the device, the corresponding 3,4,5 contact group closes, shorting all the phases. The current through consumer 2 decreases dramatically. The short-circuit current causes the operation of the automatic switch 1. 1 C.p. f-ly, 1 Il.

Description

The invention relates to electrical engineering and is intended for use in relay protection circuits of electrical installations. from short circuit currents.

The purpose of the invention is to increase the reliability and speed of protection by combining the drive functions of the make contacts and the emergency current sensor of the consumer's power line.

The drawing shows a diagram of the device.

A device for protecting a three-phase consumer from short circuit currents contains a three-phase circuit breaker! each power switching circuit of which is connected in series to the corresponding supply circuit of consumer 2, first 3, second 4 and third 5 groups of make contacts, each of which has its own drive, you. filled in the form of the magnetic fluxes of the stationary coil 6 and spring-loaded spring 7 arranged coaxially with one another with the opposite direction, with a non-zero initial pressing force on the stop of the movable coil 8, onto which sections of the input and control drive windings connected in series with a flexible jumper 9 are wound. The control input of the drive winding of each group of NO contacts through a flexible connection 12 is connected in series to the corresponding supply line between the circuit breaker 1 and consumer 2, and the terminals of each of the groups of NO contacts are connected to the supply lines of consumer 2.

The device operates as follows.

When the automatic switch 1 is switched on and the consumer is operating normally 2, the electrodynamic forces between the stationary 6 and moving 8 coils created by the currents flowing through them do not exceed the force of the springs 7. The closing contacts of groups 3-5 are open and all current flows through the consumer 2 .

During a short circuit, when a rapidly increasing current in any of the phases exceeds a predetermined value (tripping threshold), determined by the number of turns of sections 10 and 11 of the control winding of the drive and pressing the spring 7, the corresponding group of 3-5 contacts closes, shorting all phases. The current through consumer 2 decreases sharply and consumer damage does not occur. The through short-circuit current flowing through the control windings at the drives causes the circuit breaker 1 to trip and keeps the contacts of one or more groups closed until the current is limited by the circuit breaker 1.

In the device, due to the presence of additional groups of make contacts 4 and 5 and the connection of the terminals of groups 3-5 of make contacts, so that when each group is closed, all consumer supply lines are short-circuited to each other, as well as combining the functions of the high-speed drive of make contacts and emergency current sensors the consumer power lines simplifies the design of the device to protect the three-phase consumer from short circuit currents, since an additional power source is not required , the reliability of the device is increased, while the high speed of the drive and the relatively low setting of the operating current, determined by the number of turns of sections 10 and 11 of the input control winding of the drive and pressing the spring 7, provide high speed and a high level of current limitation of the device as a whole, which allows it to be used for protection of consumer semiconductor elements with a relatively small rated current.

Claims (2)

Claim 1. A device for protecting a three-phase consumer from short-circuit currents, comprising a three-phase circuit breaker with leads for connecting each power switching circuit in series to the corresponding consumer supply line, a first group of make contacts with terminals for connecting to the supply lines between the consumer and the circuit breaker, equipped with drive and designed to short circuit between the supply lines of the consumer when the drive is triggered, characterized in that, with In order to increase the reliability and speed of protection by combining the functions of the drive of the make contacts and the emergency current sensor of the consumer power line, the second and third groups of make contacts are introduced into the device, made and connected to the consumer supply lines similarly to the first group of make contacts, the control input of the drive of each group of make contacts it is intended for inclusion in series into the corresponding supply line of the consumer, while the drives of all groups of make contacts are made a threshold sensor fault currents corresponding feed lines consumer. 2. The device according to claim 1, with the fact that the drive of each group of make-up contacts is made in the form of a fixed and spring-loaded with a non-zero initial pressing force on the stop of the movable coils on which the connected successively sections of the input control winding of the drive, the fixed and movable coils in each drive being aligned with one another with the opposite directions of their magnetic fluxes.