What Is an Autorecloser?

Automatic reclosing switch A facility that automatically recloses a circuit breaker by using a mechanical device or a relay automatic device after the circuit breaker is opened for some reason. If the failure of the power system is temporary, after the circuit breaker trips and cuts off the power through the relay protection device, it will automatically reclose after a predetermined time. If the failure has been automatically eliminated, the line will resume power supply; if the failure is continuous , The circuit breaker is tripped again and no longer overlaps. According to the number of reclosing, it is divided into one reclosing and multiple reclosing; according to the number of phases, it is automatically reclosing according to the three-phase and single-phase; according to the occasion of use, it is automatically reclosing according to the single-side power supply and double-side power supply.

in

In general

Most of the faults of overhead lines in power supply systems are transient. Among these transient faults, the short circuit caused by lightning to the insulator's surface network, high-wind-induced line discharge to tree branches, wire hitting, bird damage, etc. accounts for about 80% to 90% of the total number of faults. When the faulty line is disconnected, The transient nature of the fault, the insulation strength of the fault point will be automatically restored, and the fault will be automatically eliminated. At this time, if the circuit breaker can be closed again, the power can be restored. The auto-reclosing device (ARD) uses the characteristics of transient faults. When a line fails, the circuit breaker trips under the action of the relay protection device, and at the same time, the auto-reclosing device is started. After a certain period of time, the auto-reclosing device is automatically reclosed. The device closes the circuit breaker. If the line fault is transient, the reconnection is successful and the power supply is restored; if the line fault is permanent and cannot be eliminated, the relay protection device is used to cut the line again.

The automatic reclosing device is divided into three types of three-phase reclosing, two reclosing and three reclosing. According to the statistics of the success rate of automatic reclosing of overhead lines, the power of the first resynthesis is about 80%, the power of the second resynthesis accounts for 15% to 16%, and the success rate of the third resynthesis is about 5%. Therefore, on the overhead lines of power supply systems below 35kV, three-phase primary reclosing devices are mostly used. ^[2]

(1) During normal operation, when the circuit breaker is

Circuit breaker position start includes single-phase stealth start and three-phase stealth start. The control words "Single-phase stealth allow overlap" and "Three-phase stealth allow overlap" control words are selected to be cast or retreated.

The recloser determines the start of single-phase trip or three-phase trip according to the split-phase trip input of line and line . The trip input signal of the access device requires immediate return after a successful trip. The device will confirm according to the no current of the corresponding trip phase, and judge it to be a single-phase trip start or a three-phase trip start.

For the 3 / 2-wire neutral line and one-line intermediate circuit breaker, if the same-named phase of the or line fails or the phase of the different-named phase fails, the recloser will drive the three-phase trip contact, and the three-phase trip circuit will act on the three-phase trip.

In the first line of the transformer, no reclosing is installed for the transformer side circuit breaker. When the transformer protection is activated, the reclosing function of the intermediate circuit breaker will be blocked.

1. Line protection tripping and reclosing

The reclosing start inputs include: line A, line B, line C, line A, line B, and line C. The input signals of these terminals do not need to come from the trip fixed relay, but from the trip repeater relay, that is, they are required to return immediately after a successful trip, and the recloser is started when these contacts are closed and returned.

If the reclosing device receives the trip inputs from line and line at the same time or successively during the start timing, it will discharge and output the three-trip contact.

If the reclosing device receives a trip signal from any phase and only receives a single-phase trip signal from one side, it starts a single-phase reclosing. If it receives a three-phase trip signal from either side, it starts a three-phase reclosing circuit. And when the trip starts the reclosing contact, the triple timing is started.

During the reclosing process, it will be further judged based on the contacts of the three jump relays to prevent the three jumps from being processed in a single weight.

After receiving the three-hop signal from the transformer, it will discharge without overlapping.

2. Circuit breaker position does not correspond to start

The position of the circuit breaker does not correspond to the starting reclosing, which is mainly used for the circuit breaker to jump. The device uses only three trip relay contacts to start the recloser. The secondary circuit design must ensure that the recloser is discharged by blocking the recloser input terminals during manual jump.

When it does not correspond to the start of reclosing, the judgment of single-hop or three-hop depends on the input of three jump contacts. Single-phase circuit breaker and three-phase circuit breaker stealing can be set by the control word to prohibit starting reclosing. If the control word is not turned on, the three-phase circuit breaker will report "three-trip blocking and reclosing".

Does not correspond to starting reclosing, there is no post-acceleration contact output after reclosing. ^[3]