KYN28A-12 vs KYN61-40.5: Choosing the Right Metal-Clad Switchgear for Your Voltage Class

A typical RFQ arrives with one line: "Need metal-clad switchgear, 11kV, 25 panels." Three suppliers answer with three very different quotes. One prices a 12kV withdrawable line-up, one prices a fixed-type unit, and one prices a 40.5kV line-up because "35kV" appeared somewhere on the single-line diagram.

The gap is rarely about price. KYN28A-12 and KYN61-40.5 are often compared as rival products, when they are really two voltage levels of the same substation. This guide helps you choose the right metal-clad switchgear by working from the voltage down, then checking what each choice means for room space, breakers and site conditions.

KYN28A-12

KYN61-40.5

Step 1: Start with your system voltage, not the model number

Metal-clad switchgear is medium-voltage equipment in which the busbar, circuit breaker, cable and low-voltage control sections sit in separate, grounded metal compartments. The breaker rides on a withdrawable truck (handcart), so it can be pulled out for service without touching live parts. Both models here follow this design. What separates them is the voltage class.

Two numbers cause most RFQ confusion. The nominal system voltage is what your grid runs at. The rated voltage is the highest voltage the equipment is built to carry continuously, and it is always set slightly above the grid.

Our 【12kV Metal-Clad Switchgear】 covers 3.6kV, 7.2kV and 12kV. The KYN61-40.5, our 【Metal-Clad Switchgear】 for 35kV systems, is rated at 40.5kV. Confirm the matching class for 11kV and 33kV grids with your utility.

Watch for three naming traps:

• "10kV" and "12kV" usually describe the same class. One names the grid, the other names the equipment.
• "35kV" and "40.5kV" are the same story one level up.
• 20kV, 22kV or 24kV grids sit between the two classes. Neither model fits automatically, so ask the supplier to confirm the voltage class separately before quoting.

Step 2: See how the two sit in one substation

Take a wind farm, PV plant or industrial site. Power arrives at 35kV and passes through KYN61-40.5 incoming and outgoing panels. A 35/10kV main transformer steps it down. Then KYN28A-12 panels distribute 10kV power to workshops, motors and auxiliary transformers. Many projects need both.

Here is a quick calculation. A 20 MVA transformer draws about 330A on its 35kV side (20,000 kVA ÷ (√3 × 35kV)) but about 1,155A on its 10kV side. The 35kV panels sit far below the 630A minimum busbar rating of the KYN61-40.5. The 10kV incoming panel needs a 1250A-class design.

So at 40.5kV the cabinet size is driven by insulation clearance, not current. At 12kV, current rating drives the choice, and it also decides panel width (see Step 3). If you are a dealer quoting both, ask early which side of the transformer each panel serves.

Step 3: Compare only the parameters that change your decision

A few terms in plain language:

• Short-time withstand current is the fault current a panel survives for 4 seconds while upstream protection clears the fault.
• Lightning impulse withstand voltage is the surge level the insulation must tolerate. It is roughly 2.5 times higher on the 40.5kV model.
• IP4X means the enclosure blocks solids larger than 1 mm. Here it rules out tools and wires poking into live parts, though it is not a water rating.

On the KYN28A-12, width depends on current. Panels with branch busbars up to 1250A are 800 mm wide. At 1600A and above, or with 40kA short-time current, they are 1000 mm wide. Depth is 1500 mm for cable entry and 1660 mm for overhead entry.

Factory footage of KYN28-12 metal-clad switchgear: compartmented cabinet structure and withdrawable breaker truck. A standard KYN28A-12 panel is 800–1000 mm wide, 1500–1660 mm deep and 2300 mm high.

Step 4: Count the three hidden costs before you decide

1. Room size and civil work. The smallest KYN28A-12 panel occupies about 0.8 × 1.5 m, or 1.2 m². A standard KYN61-40.5 occupies 1.4 × 2.8 m, nearly 4 m². That is roughly three times the floor area per panel. A ten-panel line-up runs about 8 m long at 12kV and 14 m at 40.5kV. The KYN61-40.5 also needs a front maintenance aisle of at least 3000 mm and rear clearance of at least 1400 mm. A compact 1200 × 2400 × 2600 mm version exists, so tell us if the building is already fixed. Also check ceiling height and the hoisting route, because each panel weighs about 2.4 tonnes.

2. Breaker choice. At 12kV, a domestic VS1 vacuum breaker is the standard option and the imported VD4 is the premium one. At 40.5kV, you choose between a domestic vacuum breaker and an imported SF6 breaker. Vacuum breakers extinguish the arc inside a sealed bottle. SF6 breakers use insulating gas. Imported breakers can mean longer waits for spare parts, so agree the spares list and handcart quantity at order stage rather than after commissioning.

3. Site conditions. The standard design assumes ambient temperature from −15°C to +40°C and altitude up to 1000 m. Humidity should be at or below 95% daily average, and the air free of corrosive gas and heavy contamination. Many export sites sit higher, so please tell us the altitude in advance and our factory will evaluate it. Quote your project's actual conditions in the RFQ.

Standards and delivery are simpler. Both models are built to GB 3906 and GB/T 11022, and we can customise to your own standard on request. There is no minimum order quantity, and a single panel can ship. Lead time depends on order volume, typically between 30 and 60 days.

Assembly of switchgear panels in our Jiangshan workshop. Each unit is built to order, and a single panel can ship.

Step 5: Learn from projects already running

In Tanzania, a KYN61-40.5 line-up went from unpacking to energisation in five days. It then ran a 72-hour continuous energised test, with partial discharge below 10 pC. Remote 3D animation walkthroughs resolved a busbar compartment alignment question without a site visit. When the local grid proved unstable, the protection settings were upgraded on site.

In Shangrao, Jiangxi, a batch of KYN28-12 panels was installed and accepted within five days. When a ground fault appeared on site, our team restored power within two hours.

Both cases show that fast commissioning depends on correct specification from day one, not on the model name.

Your pre-RFQ checklist

Before you request a quote, gather the following. It will save you at least one round of emails.

1. System voltage and frequency, including any 20–24kV segments.
2. Transformer capacity and voltage ratio.
3. Short-circuit current at the busbar.
4. Single-line diagram, main circuit scheme number and room floor plan.
5. Site altitude, temperature range and humidity.
6. Breaker preference, standards to follow (GB, or your own), cabinet colour and spare parts.

No drawings yet? Send us the site details and the power of the equipment you plan to run, along with the technical parameters you do have. Our engineers can propose a scheme from that.

Need help deciding between the two classes? Start with our 【Medium Voltage Metal-Clad Switchgear】 for 10kV rooms, or send your drawings and let us review them.

FAQ

• Can I use KYN28A-12 on an 11kV system?

Normally yes. 11kV grids are usually served by 12kV-class equipment, but confirm the class and short-circuit level with your utility.

• Is KYN61-40.5 suitable for wind and PV projects?

Yes. It is built for 35kV collection and incoming lines in wind, PV and storage stations, and supports remote monitoring and anti-islanding protection.

• What is the difference between metal-clad and metal-enclosed switchgear?

Metal-clad is one type of metal-enclosed switchgear. It adds grounded metal barriers between compartments and a withdrawable breaker. Basic metal-enclosed designs may not.

• Do you offer 24kV metal-clad switchgear?

For 20kV, 22kV or 24kV grids, please send your parameters so we can confirm the voltage class separately. We do not recommend a model without that review.

• Is there a minimum order, and how long is delivery?

There is no minimum. Delivery is typically 30 to 60 days depending on the quantity.