Distribution transformers
1000 kVA transformer
A 1000 kVA transformer delivers 1,443 A at 400 V and draws about 52 A from an 11 kV network. At this rating the transformer feeder can be a switch fuse or a circuit breaker, and the choice belongs in the specification.
- Rated current at 400 V
- 1,443 Acalculated
- Primary current at 11 kV
- 52 Acalculated
- Incomer frame at 400 V
- 1600 Ayour designer confirms it
- Load at power factor 0.9
- 900 kWat rated current
- EU load loss ceiling, liquid
- ≤ 7,600 WTier 2, Table I.1
- EU no load loss ceiling, liquid
- ≤ 693 WTier 2, Table I.1
Where 1000 kVA is specified
One megavolt ampere is a round figure in specifications for large commercial buildings, logistics halls, hospitals and factory extensions. At a power factor of 0.9 it carries 900 kW.
A distribution network operator's published drawings list 1000 kVA ground mounted units for 11 kV networks, alongside 500, 800 and 1500 kVA.
Under regulation 27 of the ESQCR the UK declared low voltage is 230 V, 10 % above or 6 % below. One operator states that it chooses a 433 V no load secondary to help provide that declared voltage.
Rated currents at 1000 kVA
| Primary | Secondary | Primary current | Secondary current |
|---|---|---|---|
| 11 kV | 400 V | 52 A | 1,443 A |
| 11 kV | 433 V | 52 A | 1,333 A |
| 20 kV | 400 V | 29 A | 1,443 A |
| 13.8 kV | 480 V | 42 A | 1,203 A |
Switch fuse or circuit breaker
At 1000 kVA the transformer feeder in the ring main unit can be specified either way. A switch fuse is simpler and has no relay to set. A circuit breaker with a protection relay gives adjustable protection and selectivity with the network, and some operators and designers require it at this size.
The fuse link comes from the fuse maker's selection table for the transformer rating, the network voltage and the inrush the unit draws. Your designer then checks it against the downstream protection.
A 1600 A incomer
1,443 A needs an incomer in the 1600 A frame, usually an air circuit breaker. At this current busbar trunking is often a neater link to the board than several parallel cable runs.
At 6 percent impedance the fault contribution at 400 V reaches about 24.1 kA as an upper bound. Two 1000 kVA units in parallel double that figure. That is one reason large sites split their boards.
Real power at 1000 kVA
| Load power factor | Real power |
|---|---|
| 0.80 | 800 kW |
| 0.90 | 900 kW |
| 0.95 | 950 kW |
What sets the price at 1000 kVA
The price of a 1000 kVA unit moves with the construction, liquid immersed or cast resin, and with how far below the loss ceiling the design sits. The voltage pair and tapping, the fittings and cable boxes, the standard at the destination and the delivery terms move it too.
Two offers for the same rating are comparable once those items match. We set them out line by line, with the datasheet, the drawing and the test documents for each unit offered.
The UK network operators' range
ENA TS 35-1, which UK network operators use for their distribution transformers, now Issue 8 of March 2026, covers units from 25 to 2000 kVA, so 1000 kVA sits well inside the range an operator adopts. Tier 2 brought the GB ceilings for a liquid immersed 1000 kVA unit down from 10,500 W and 770 W to 7,600 W and 693 W.
What a 1000 kVA transformer request needs
- 1000 kVA, or the load in kW and its power factor
- A switch fuse or a circuit breaker for the transformer feeder, as the ring main unit or the network operator requires
- Busbar trunking or parallel cables between the unit and its 1600 A incomer
- Liquid immersed or cast resin, and the room or plinth it stands on
Specification template
Fill it in on screen or by hand, then upload it with your request.
Questions buyers ask
How many amps is a 1000 kVA transformer?
1,443 A at 400 V, 1,333 A at 433 V and 1,203 A at 480 V on the low voltage side. On the primary it is about 52 A at 11 kV and 29 A at 20 kV.
What load can a 1000 kVA transformer carry?
800 kW at a power factor of 0.8, 900 kW at 0.9 and 950 kW at 0.95, at rated current and continuous duty. Diversity, harmonics, ambient temperature and the largest motor start change how much of that is usable.
How much does a 1000 kVA transformer cost?
It depends on the construction, the loss level, the voltage pair and tapping, the fittings, the standard and the delivery terms, and it moves with manufacturer loading. Each offer we return is priced for your specification and states those items.