Products

Transformers

Distribution, dry type, oil immersed, pad mounted and power transformers, sourced against the rating, the voltage pair, the standard and the conditions where the unit will stand.

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Specified by

Rating: kVA or MVAnever kW, because the unit carries apparent power
Voltage pair: primary and secondarythe primary is set by the network at the connection point
Construction: liquid immersed or dry typeset by where the unit stands and whether oil is acceptable there
Standard: IEC or IEEEset by the specification and the destination market

Outdoor power transformer with high and low voltage bushings, surge arresters and a radiator bank against a blue sky — A power transformer at an outdoor substation, with its bushings, surge arresters and radiator bank.Photo: Yoshieslunchbox, CC BY-SA 4.0, source. Shown for illustration. Not a product of this company, and no stock or manufacturer relationship is implied.

A transformer is chosen by a short sequence of decisions taken in order. The rating follows from the load and from the starting behaviour of the largest motor on it. The voltage pair follows from the network on the primary side and from the installation on the secondary. The construction follows from where the unit stands. Everything after that, the enclosure, the tapping range, the fittings and the loss requirement, follows from those three.

Capacity is stated in kVA or MVA because a transformer is rated for apparent power. A load described in kilowatts has to be converted with its power factor before it can be compared with a rating, and skipping that step is one of the commonest reasons a unit arrives undersized.

Transformer types

Distribution

Distribution transformersMedium voltage to low voltage, liquid immersed or dry type, in the standard rating series.Oil immersed transformersMineral oil or ester filled, hermetically sealed or with a conservator, for outdoor and plant room use.Dry type transformersCast resin units for indoor and occupied spaces, with no insulating liquid to contain.

Network and utility

Pad mounted transformersCompartmental, tamper resistant units for underground distribution on North American style networks.Power transformersMVA rated units for primary substations and large connections, engineered per project.

Choosing the construction

Construction	Typical placement	Why it gets chosen
Liquid immersed, mineral oil	Outdoors, or in a dedicated transformer room	Usually lower cost per kVA, and suits outdoor installation
Liquid immersed, ester	Where fire safety or water protection governs	Ester liquids have a higher fire point and better biodegradability than mineral oil
Dry type, cast resin	Indoors, including occupied buildings	No insulating liquid, so no liquid containment and a lower fire load
Pad mounted	Outdoors at ground level, on North American style networks	A tamper resistant cabinet that needs no separate enclosure

Distribution transformer ratings

Rating	Full load current at 400 V	Full load current at 433 V
100 kVA	144 A	133 A
160 kVA	231 A	213 A
200 kVA	289 A	267 A
250 kVA	361 A	333 A
315 kVA	455 A	420 A
400 kVA	577 A	533 A
500 kVA	722 A	667 A
630 kVA	909 A	840 A
800 kVA	1155 A	1067 A
1000 kVA	1443 A	1333 A
1250 kVA	1804 A	1667 A
1600 kVA	2309 A	2133 A
2000 kVA	2887 A	2667 A
2500 kVA	3608 A	3333 A

Rated current at 400 V, three phase. Each rating page covers voltage configurations, loss limits, documents and what we need to quote.

Common questions

Do you publish prices?

No, and not because they are hidden. A transformer price depends on rating, loss level, voltage pair, tapping, enclosure, standard and delivery basis. A figure without those is not a price. Every quotation states the specification it applies to.

Can you source to a North American specification as well as IEC?

A requirement written to IEEE or to IEC can be submitted. Whether a unit to that specification can be supplied to your destination is confirmed per enquiry, and we say so plainly when it cannot.

Send us the requirement

Send the rating, the voltage and the destination, or submit the specification, drawing or nameplate. Anything missing is raised before it reaches a supplier.