Primary switchgear ZF28-550


Electrical characteristics
SF6 gas-insulated
circuit breaker
Primary current

4,000 A, 5,000 A, 6,300 A


550 kV


ZF28-550 type GIS/ ZH28-550 type HGIS is composed of standard modules through flanged joint, which can meet the demand for substation optimization design through the flexible combination between modules. It saves space and conforms to technical requests.


1) The domestic first high power spring operation mechanism of circuit breaker has the small volume and is safe

and stable, free of maintenance. high reliable and conform to oil free and gas free requirements for operation


2) Interrupter unit adopts shunt capacitor to balance the voltage between open contacts It improves short line

fault breaking capability;

3) Excellent insulation level and low partial discharge. The only company in the industry that can achieve: under

the 80% power-frequency withstand voltage (80%×740kV = 592kV), the partial discharge of intervals is lower

than 5pC, the partial discharge of the insulator is lower than 3pC. It’s better than the IEC standard that the

partial discharge should be lower than 5pC under 1.2 times phase voltage (1.2×550/√3 = 381kV);

4) The insulator quality is stable and reliable. The basin-type insulator pouring process reaches the international

advanced level;

II. Application environment

1. Installation site: indoor/outdoor;

2. Ambient temperature:

Maximum temperature: +55℃;

Minimum temperature: -40℃;

Maximum daily temperature difference: 32 K;

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