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sectionalizer

The electric sectionalizer has been developed for use on overhead distribution lines to improve reliability and service continuity. It enhances the protection of the distribution system in a simple, economical way which is free from maintenance and spares.

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The electric sectionalizer has been developed for use on overhead distribution lines to improve reliability and service continuity. It enhances the protection of the distribution system in a simple, economical way which is free from maintenance and spares.

Introduction
Operational principle
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) opens, the circuit loses voltage and the current is lower than 300mA, the electronic controller can remember this opening time as a "count". As it accumulate 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) closes to restore power supply to the healthy section of the system to limit outage scope and protect the main feeder 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.
Counts
The number of counts differentiates real faults from transient faults. When the preset number of counts is registered, the electronic sectionalizer will operate.
The sectionalizer can be set to 1, 2, 3, 4 counts. It registers a count when a current dead time exceeding 200 milliseconds occurs, immediately after a current pick up. This ensures the sectionalizer only registers a count when a recloser has tripped due to a fault current.
The count setting should be one count less than the immediate upstream recloser.
Pick up current
The pick up current is the threshold, which must be exceeded in order to register a count. The pick up requires a minimum fault pulse that is 10% greater than the pick up current setting and is longer than 20 milliseconds in duration.
Resetting
The electronic sectionalizer will reset itself during the drop out operation. Do not need remove the unit from its mount using a hook stick and reset it manually.
Service conditions
1.The ambient air temperature is not above 55ºC or below -40ºC.
2.The average value of the ambient temperature, measured over a period of 24h,does not exceed 25ºC.
3.The altitude does not exceed 1000 m (3300ft).
4.The wind speed does not exceed 34 m/s (corresponding to 700 Pa on cylindrical surfaces).
5.The ice coating does not exceed 1mm.
6.The sectionalizer should not apply to those flammable, explosive, corrosive and severe vibration conditions. As to other service conditions not covered in the manual, please contact and consult with the manufacturer for detail information.
Designator and its meaning

Technical data
Rated actuating current: 8 to 400A
Reclaim time: 20 ±5%s
Operation counts: 1-4
Sensitivity of pick up current: ±10% 
Max. load current prior to operation: 0.3A
Min. recloser dead time: 500ms
Min. duration of fault pulse: 10ms
Selection list
Please inform the order before ordering. For example:
Pick up current (A)

Count/counts

I1

I2

I3

I4

I5

1.2.3.4
Note: Please view the label to know the section current(I1, I2, I3, I4, I5) .

Sectionalizer setting  guide
1.
Current setting
The sectionalizer current setting must be selected at 20% below the minimum associated recloser or circuit breaker trip current.
2.Number of count setting
Generally the number of count settings should be 'one' less than the number of trips to lockout of the recloser or circuit breaker.

Application
Normally, the sectionalizer is applied in conjunction with an upstream recloser or circuit breaker.For Example:
The recloser applied in the substation is set (1 fast and 3 slow) 4 shots to lockout and 6 units cutout 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 time. As shown in the following figure:

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.
If a fault E2 in section L6, a fault current flow the recloser and sectionalizer F1, F5, the recloser trip, if the fault is temporary, the recloser reclose to restore the line in service, then the sectionalizer F1, F5 remains 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 trip again, all the line lost voltage and the sectionalizer F5 trip to isolate fault section L6 after it reaches the presetting count number 2, the sectionalizer F1 remain closes state since it does not reach the presetting count number. The recloser reclose again and restore the healthy section L1, L2, L3, L4, L5 to service.

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 F1 remains closed and resets to its orginal 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 trip again 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.