High Voltage Electric Automatic Sectionalizer Use on Overhead Distribution Lines

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 countsis registered, the electronic sectionalizer willoperate.
The sectionalizer can be set to 1, 2, 3, 4 counts. It registers a count when a current dead time exceeding200 milliseconds occurs, immediately after a current pick up. This ensures the sectionalizer only registers acount when a recloser has tripped due to a faultcurrent.
The count setting should be one count less than the immediate upstreamrecloser.

Pick upcurrent
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
Theelectronicsectionalizerwillresetitselfduringthedropoutoperation.Do not need remove the unit from itsmount using a hook stick and reset itmanually.

Service conditions
1.The ambient air temperature is not above 55ºC or below-40ºC.
2.Theaveragevalueoftheambienttemperature,measuredoveraperiodof24h,doesnotexceed 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 cylindricalsurfaces).
5.The ice coating does not exceed1mm.
6.Thesectionalizershouldnotapplytothoseflammable,explosive,corrosiveandseverevibrationconditions. As to other service conditions not covered in the manual, please contact and consult with the manufacturerfor detailinformation.

Designator and itsmeaning

Technical data
Rated actuating current: 8 to400A
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