Auto Link Electronic Sectionalizer

The current transformer built in the cutout sectionalizer can detect the current of the main circuit and send the output to the electronic control for digital handling. When a fault occurs, the upstream recloser (or circuit breaker) open, the circuit loses voltage and the current is lower than 300mA, the electronic controller can remember this opening time as a “count", when it reach the presetting number (1 to 4), the sectionalizer will automatic trips within 180ms of fault interruption to isolate fault. Then the upstream recloser ( or circuit breaker) close to restore power supply to the healthy section of the system to limit outage scope and protect the mainfeeder in service. If the fault is temporary and is cleared before the sectionalizer counter reaches the presetting number, the sectionalizer remains closed and resets to its original state after its reset time expires.

1. upper moving contact
2. conductive rod
3. control part
4. current transformer
5. lower moving contact
6. reset spring
7. open detent
8. trip spring

APPLICATION

Normally, the sectionalizer is applied in conjunction with an upstream recloser or circuit breaker.Refer to the diagram.

For example:

The recloser applied in the substation is set( “1 fast and 2 slower’)3 shots to lockout and 6 unitscutout sectionalizers (F1, F2, F3, F4, F5, F6) are applied in the four branch line to separate 7 section( L1, L2, L3, L4, L5, L6, L7). The counts of F1 is set to 3 time, F2, F3, F5, are set to 2 times and F4,F6 are set to 1 times.

1. If there is a fault E1 in section L5, a fault current flow the recloser and sectionalizer F1, F3, F4,The recloser trip and all the line lost voltage, The sectionalizer F4 trip after it reach to the presetting “count" number 1 and isolate the fault section L5, the rescloser reclose and restore the healthy section L1, L2, L3, L4, L6, L7 to service.

2. If a fault E2 in section L6, a fault current flow the recloser and sectionalizer F1, F5,the reclosertrips; if the fault is temporary, the recloser reclosesto restore the line in service, then the sectionalizer F1, F5 remains closed and resets to its original state after a presetting time since itdoes not reach the presetting count number,. if the fault is permanent, the recloser failsto reclose successfully and trip again, all the line lost voltage and the sectionalizer F5 trip to isolate faultsection L6 after it reaches the presetting count number.
3. The sectionalizer F1 remain closes state since it does not reach the presetting count number. The recloser reclosesagain and restore the healthy section L1, L2, L3, L4, L5, to service.

4.If a fault E3 in section L2, a fault current flow the recloser and sectionalizer F1, the recloser trip.If the fault is temporary the recloser reclose to restore the line in service, then the sectionalizer F1remains closed and resets to its original state after a presetting time since it does not reach the presetting count number. If the fault is permanent,the recloser fail to reclose successfully and tripagain all the line lost voltage and the sectionalizer F1 trip to isolate fault section L2 after it reach the presetting count number 3, The recloser reclose again and restore the healthy section L1 to service.

The count number of sectionalizer is set 1 time normally as it applied in the end of substation
because almost fault occurring at the end of substation is permanent and is set 2 or 3 times applied
on the overhead line because almost fault applied on the overhead line is temporary. In this co-ordination, the sectionalizer can easily and optimized co-ordinate.