KYN28A-12 (KZN1-12) indoor metal-clad withdrawable switchgear (hereinafter referred to as switchgear) is a complete distribution assembly for 3–10kV three-phase AC 50Hz single-bus and single-bus sectionalized systems. It is mainly used in power plants, small and medium generator outgoing circuits, industrial and mining distribution, secondary substation receiving and outgoing service, and large HV motor starting, providing control, protection and monitoring functions.

This switchgear complies with IEC 62271-200, GB 3906 and related standards. It features interlocking to prevent pushing or withdrawing the circuit-breaker truck under load, prevent erroneous switching operations, prevent closing the circuit breaker when the earthing switch is closed, prevent entry into live compartments and prevent closing the earthing switch when energized. It can be fitted with ABB VD4, GE VB2 vacuum circuit breakers, or domestically produced VS1 and VT2 VCBs, making it a high-performance distribution solution.

3.1 Normal service conditions

1. Altitude not exceeding 1000m;

2. Ambient air temperature: upper limit +40°C, lower limit -10°C (storage/transport down to -25°C permitted);

3. Humidity: daily average relative humidity not exceeding 95%; monthly average not exceeding 90%;

4. Seismic intensity not exceeding magnitude 8;

5. Suitable for condensing and Class II pollution environments.

3.2 Special service conditions

When service conditions exceed the above limits, the user and manufacturer shall agree on appropriate measures.

a. Product certificate of conformity   b. Packing list   c. Factory test report   d. Operation manual

e. Equipment list     f. Secondary wiring diagram    g. Drawn products supplied per drawing list and equipment schedule

h. Withdrawable truck operating crank, earthing switch operating handle and truck transfer trolley (for orders below 10 units: one set per 5 units; for orders above 10 units: one additional set per 10 units)

The following information shall be provided when ordering:

a. Main single-line diagram number, arrangement diagram and floor layout;

b. Secondary schematic and terminal arrangement (manufacturer standard if not supplied);

c. Model, specification and quantity of switchgear components;

d. Electrical equipment summary list;

e. Busbar bridge span and height if required (between rows or wall-to-cabinet);

f. Special environmental conditions;

g. Additional accessories beyond standard scope, if any.