KYN28A-12 Metal-Clad Mid-Mounted Switchgear

Start from the voltage class. 40.5 kV means KYN61-40.5, 24 kV means KYN□-24, and only at 12 kV and below does the choice open up between KYN28A-12, KYN550-12 and YF-KYN450-12. Among those three, KYN28A-12 carries the widest fault range (16-50 kA) and rated current to 3150 A, which makes it the broadest fit; KYN550-12 takes the main busbar to 4000 A with cubicle widths from 550 to 1000 mm, for high current where width is also constrained; YF-KYN450-12 is the compact type at 475-550 mm wide and 1100 mm deep, for switchrooms short of floor area. The series page carries the full five-model comparison.

They are fixed together. The voltage class follows the nominal system voltage and the insulation level follows from it: 3.6 kV pairs with 24 kV power-frequency withstand and 40 kV lightning impulse; 7.2 kV with 32 kV and 60 kV; 12 kV with 42 kV and 75 kV. The three sets are paired, so a lower-class insulation level cannot be used at a higher voltage. Give the nominal and the highest operating system voltage with the enquiry and the insulation level follows.

The fault level follows the system fault capacity at the point of installation and the rated current follows the circuit load; the two are set independently. Send the system fault capacity or the short-circuit calculation and the level is taken from the six steps of 16, 20, 25, 31.5, 40 and 50 kA at not less than the calculated value, with peak withstand current following at 40, 50, 63, 80, 100 or 125 kA. The rated current is then chosen between 630 and 3150 A against the circuit duty.

A complete order designation is KYN28A-12 followed by four positions: the primary scheme number, which says whether the cubicle is an incomer, a feeder, a bus-tie or a metering cubicle; the operating-mechanism code, D for magnetic and T for spring; the rated current; and the rated breaking current. The first two follow from where the cubicle sits in the system and from the control supply conditions, and the last two are the answers to the two questions above. Send the single-line diagram and the circuit schedule and all four can be set cubicle by cubicle.

The two values correspond to two insulation paths. Where the path runs wholly through air, the phase-to-phase clearance is not less than 125 mm; where part of it runs through solid insulation, the clearance is not less than 60 mm. The smaller figure is permitted because the solid insulation carries part of the duty, and GB 3906 gives the pair for 12 kV. Neither depends on the main switch — both hold with a ZN63A(VS1) vacuum circuit breaker and with a C3-series fixed load-break switch — and both can be checked cubicle by cubicle at drawing stage against the actual primary scheme.

The choice follows the circuit function. Incomer, feeder and bus-tie circuits that have to break fault current take a ZN63A(VS1) vacuum circuit breaker; circuits that only switch load current, with upstream protection coordinated, can take a C3-series fixed load-break switch. Where remote supervision is required, a communication interface is added for remote control and telemetry, with the protocol and point list agreed at technical specification stage. The main switch type also affects the truck and fixed-contact box dimensions, so state it when sending the single-line diagram.

Three items are enough for a preliminary proposal: the single-line diagram, the voltage class with the rated current, and the system fault capacity. For a contract-grade quotation, add the cubicle count with the primary scheme for each, the control supply type and voltage, the metering and protection requirements, the cable entry arrangement and cable sizes, the communication interface, the switchroom dimensions and depth limit, and the standards and document list for the destination market.

Yes. Switchgear is supplied as equipment; an MV switchgear E-House or power module is supplied as an enclosure — the first is the cubicle itself, the second covers the enclosure, the equipment layout, the auxiliary systems and interface integration. Where a KYN28A-12 line-up is delivered as the primary equipment inside an E-House, ETENZ develops the line-up layout, busbar connections and internal interfaces together, and the delivery boundary is set once at contract stage.