Auto Recloser Control Unit With Metering Unit

Additional Details

A circuit breaker whose tripping and reclosing functions are programmed and controlled automatically by an intelligent control unit is called as ‘AUTO RECLOSER’. Auto Recloser can interrupt fault currents, and also programmed to reclose to restore the supply. The supply gets restored if the fault is of transient in nature. If the fault is of permanent type, the Auto Recloser tries to reclose the supply in two or three attempts (as set in the program) and finally goes to ‘lock out’ status, after which manual intervention is essential.

The control unit is facilitated with manual control switches for circuit breaker trip and close operations. The circuit breaker status are indicated through indicating lamps. The operation of the circuit breaker is monitored by control unit after extending the trip / re-closing. The lockout contact will operate if breaker is mal-operated. The control unit has inbuilt trip counter which counts number of trips after installation. The count can be reset. The fault zone indicator is very useful only when several sectionalisers are used along the feeder. The zone numbers are based on time interval of closing the sectionaliser from the time of closing of auto recloser. The zone number will be displayed on the display. Zone number gives very useful information to locate the faulty section of the feeder quickly. Inbuilt power pack will generate sufficient DC power supply required to operate circuit breaker.

The lockout contact will operate following conditions.

1. On permanent fault.

2. Breaker mal-operation

3. Very low voltage.

4. Trip when unit is manual modez

Features:

Three phase over current and earth fault protection.

Programmable operating characteristics

Programmable auto reclosing facility.

Independent trip sequence setting (IDMT / Def. time)

Under voltage blocking for breaker close

Trip counter.

Fault zone indication.

Breaker mal-operation indication.

Auto / Manual control.

Breaker status indication.

Trivector meter to record energy and Load parameters.

Ammeter and voltmeter with selector switch

Separate cabinets for control unit and meter unit, which are mechanically fastened together

Cabinet suitable for different types of pole mounting.

Application:

Electrical Power for rural areas is supplied by 11kV overhead lines. They are exposed to several faults like,lightning, heavy wind, fall of tree branches, fault created by animals / birds etc. When a fault occurs, the protection system trips the circuit breaker to prevent / minimize the damage. It is expected to locate the fault, clear and then restore the supply by reclosing the circuit breaker. It takes more time between power outage and restoration. More than 70% of the faults are observed to be temporary / transient in nature. Hence, power outage time can be reduced if the reclosing function is automated and carefully planned.

Settings:

Operating characteristics (Separate for Ph & EF) : 1) 3.0s Normal Inverse   2) 1.3s Normal Inverse

Phase O/c ( I> ) : 20 to 200% in steps of 5 %

Earth fault : 5 to 50% in steps of 1%

TMS (Phase & E/F ) :0.02 to 1.0 in steps of 0.01

Definite time (Phase & E/F ):0.06s to 0.24s in steps of 0.01s

High set (Ph. & EF) :2 to 16 times I> setting

Max. Shots (re-closing) :Maximum of 3

Dead time 1 to 3 : 0.5 to 250s In steps of 0.1s

Reclaim time :10 to 250s In steps of 1s

Cold load pickup (CLP): 2 to 20 times the O/c (IDMT)

CLP Delay :0.06s to 1.0s in steps of 0.01s