Disconnector Center Break Isolator and Double Break Isolator Center
DISCONNECTOR TYPE:GW4-72.5DW/5000A , 7
2.5 KV,5000A,SHORT TIME WITHSTAND CURRENT40(KA),,
MODE OF OPERATION:THE MAIN ISOLATION SWITCH: MOTORIZED-THE EARTH SWITCH:MOTORIZED,WEIGHT 700KG

Disconnector for 220kV Substation

Center- breaker disconnectors GW4(up to 550kV)

Introduciton;

The following documents were referred to during the preparation of this specification. In case of conflict, the
provisions of this specification shall take precedence.

IEC 129:1975: Alternating Current Disconnectors (Isolators) and Earthing Switches

IEC 60694:2002: Common Specifications for High Voltage Switchgear and Controlgear

BS 729: Hot dip galvanized coating on iron and steel articles

IEC62271-102

Isolator (Disconnector) – a mechanical switching device which provides, in the open position, an isolating
distance in accordance with Electrical Safety requirements.



SERVICE CONDITIONS

The isolator shall be suitable for continuous operation outdoors in tropical areas at altitudes of up to 2200m
above sea level, humidities of up to 90%, average ambient temperature of +30ºC with a minimum of -1ºC and a
maximum of +40ºC and heavy saline conditions along the coast.



DESIGN AND CONSTRUCTION

1 The Isolator, Solid Link shall be designed and constructed in accordance with IEC 129 and IEC 60694.

2 The isolating link shall be of the vertical opening, designed for single phase manual operation. It shall be
easily removed and replaced by using a portable operating rod.

3 The isolating link shall incorporate double porcelain insulators to suit voltage requirements and mounted on
hot dipped galvanised steel under base suitable for vertical mounting.

4 The isolating link shall be arranged so that each unit is mounted independently on an angle bracket. It shall
be supplied complete with the angle bracket and accessories suitable for mounting on ‘U’ type steel channel.
The drawings to be submitted shall indicate all the applicable mounting positions.

5 The isolator shall be designed such that in fully open position, it shall provide adequate electrical isolation
between the contacts on each phase. It shall conform to the requirement as single point isolation for safety.

6 All steel parts shall be hot dip galvanized to BS 729. The minimum coating of galvanizing required is 80
microns.

7 The solid link shall be removable from the mounting by use of operating rod.

8 All current carrying parts of the isolator shall be made of high conductivity material.

9 The isolator shall be fitted with clamp connectors for Aluminium (ACSR) conductor of Aluminium
(ACSR)conductor of up to 18.2mm diameter.

Main Technical Data :


Rated voltage:12-550kV

Rated current: up to 5000A

Rated frequency:50/60Hz

Short time withstand current :up to 63kA

Mechanical endurance:M2

Ice breaking capacity:10-20mm

Rated insulation level:According to the latest IEC 62271-1

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