LOW VOLTAGE TRANSFORMERS - Frequently Asked Questions

THE purpose of a low-voltage transformer is to change the voltage of electricity flowing in a circuit. Transformers can be used to both increase and decrease voltage. 

Power transformers have an input voltage (primary) and output voltage (secondary). 

A step-up transformer converts a low voltage to a high voltage. Usually this is 110V up to 240V. Step-up transformers are less common, but we do manufacture them at Transpower, and can also offer a portable 3kVA step-up tool/site transformer from stock. 

A step-down transformer converts a high voltage to a lower voltage. Usually either 240V or 415V down to 110V. Step-down transformers are what we mostly produce at Transpower.

Yes. Most of the low-voltage transformers we supply are 110V transformers, converting either 240V or 415V down to 110V, step-down transformers. We can also offer step-up transformers. 110V site transformers are an item we generally have in stock at Transpower, and can be supplied quickly - please contact if if your requirement is urgent. 

Also known as an isolation transformer. Most of the transformers we make are double-wound, but not all. Double-wound transformers (isolation transformers) work on the principle of mutual inductance; they have a primary and secondary coil and a change in the current of one coil will affect the current and voltage on the second coil, even if they are not touching. Because the two coils are not touching (i.e. isolated from each other) there is some protection against power surges. With a double-wound transformer (isolation transformer), step-up is achieved by having more coils in the secondary (output) coil, while step-down is achieved by having more coils in the primary (input) coil.

Auto-wound transformers use a single coil, which acts as both the primary and secondary winding, so there is no isolation of the input and output, and consequently no protection from power surges. Auto-wound transformers can become step-up or step-down, by ‘tapping’ the coil at a certain point. All our auto-wound transformers are custom-build, so please ask for details and we would be happy to advise further.  

Intermittent/tool rated transformers cannot be used continuously, they are only suitable for use in short bursts. Some intermittent tool-rated transformers can be operated continuously, at a lower power. We can supply a range of intermittent/tool rated workshop & site transformers. If you need further advice on this, please ask.

Sitemasters are portable site transformers, also known as site power transformers, and are commonly used on building and construction sites for powering tools and machinery. We can supply sitemasters as 5kVA transformers, 10kVA transformers, 15kVA transformers and 20kVA transformers. They are normally step-down transformers, either 240V to 110V transformers or 415V to 110V transformers, but step-up is possible. Sitemasters can be supplied as either  IP44 or IP65 and we can also supply sitemasters on wheels. Many of our 110V sitemaster transformers can be supplied from stock. 

A continuous transformer allows for exactly what it suggests, continuous use. We can supply continuous transformers as site, workshop, distribution and panel transformers. An intermittent transformer, which is the alternative, could only be safely used in bursts.

We mainly work from 12VA to 15kVA (single phase) and up to 45kVA (three phase) but we can actually supply transformers in up to 500kVA. We can also custom-build maintenance panels with integral transformers at the Ceenorm site in Telford. Please ask us for more information and someone from our custom-build division will be happy to advise. 

Yes, we can custom build bespoke transformers to suit exact requirements, and our knowledgeable team can help you work out what that requirement is if needed. Whether it is intermittent or continuous rated, a step-down transformer or a step-up transformer, and isolation (double-wound) or an auto-wound transformer, we can help with your needs. 

We can custom build bespoke transformers to suit exact requirements, this includes low-voltage transformers allowing UK users to run imported machinery. For example, we have supplied 20 kVA isolation transformers to convert a 415V 3-phase supply to 380V 3-phase supply (for a Chinese machine) and a 415 3-phase supply to 240V 3-phase supply (for a Japanese machine). If you think we can help, please get in touch with the team. . 

Single or three phase transformers are certainly the most common, but we can also manufacture two-phase transformers if required. Ask us for further information. 

Some of our low-voltage transformers are supplied from stock - in particular we carry stock of a number of 240V to 110V sitemaster transformers and portable tool transformers, as well as a 110V to 240V step-up portable tool transformer - others are made to order in just a few days (normally 3-5 days depending on how busy we are). And some low-voltage power transformers are custom built/bespoke builds, with a lead time of 3-5 days once the final specification for the bespoke transformer has been agreed. 

As well as low-voltage transformers we can supply 110V junction boxes and 110V & 240V extension leads. Ceenorm (owners of Transpower) can supply a wide range of industrial plugs & sockets, electricians' tools and more. We also have a custom build team in Telford who specialise in custom built distribution units/equipment. And Cablecaddy, which is also owned by Ceenorm, can supply a wide range of industrial cable reels under the popular Marcaddy brand - including IP65-rated cable reels for outdoor use.  

Yes, our manufacturing site is ISO9001-2015 accredited (as is the Ceenorm manufacturing site in Telford). You can download a copy of our ISO9001-2015 certificate below.

Transpower Engineering is owned by Ceenorm UK Ltd - a supplier of industrial plugs & sockets, electricians tools and more. Ceenorm also design and builds bespoke distribution units, using Transpower's low-voltage transformer expertise when required. Transpower's Manchester site also acts as a collection point for Ceenorm in the north west. 

Yes. Transpower holds stock of some popular industrial plugs & sockets (as well as of our low voltage sitemaster transformers and portable tool transformers). We only hold stock of our most popular, faster moving lines. Stock can also be moved from Telford for collection.