Tramo ETV manufactures world-class Transformers

A Qualified Supplier of Transformers

At TRAMO ETV we specialize in manufacturing and supplying low voltage transformers and inductors for marine and heavy industry as well as several special applications. Our product range of low voltage transformers is very wide and ranges from 15 VA up to 250kVA. Most of what we manufacture is customized. So, are you looking for a manufacturer of a customized low voltage transformer that is used to delivering tailor-made solutions? Then you have found the right one!

We also offer a wide range of accessories that can be included such as pre-magnetization systems, fan motor starter units, or additional windings for auxiliary power. If you have requests for special accessories for your low voltage transformer please contact us or include it in your request and we will try to help you in the best way.

TRAMO ETV’s transformers are always manufactured and delivered ready for direct installation and use. All our transformers are built according to SS-EN IEC 60076-11.

We are manufacturer of various Transformer types

We use the following product names: OFS/OFL, VF/GF, TOFS/TOFL, TVF/TGF, FTPK/TFTPK, OFB, OFU, OFK. Read more about the different types below:

Measurement transformer is the collective name for current transformer and voltage transformer. It is also known as an instrument transformer.

A measurement transformer is an electrical device used to measure high voltages or currents and convert them to a proportional and more manageable level for reading and measurement. The primary winding of a current or voltage transformer is connected in series with the current to be measured, and the secondary winding is connected to the measuring instrument. The ratio between the primary and secondary current is determined by the number of turns in each winding.

Measurement transformers are particularly important components for ensuring correct measurement. They enable the use of correctly dimensioned and sensitive measuring instruments while providing complete isolation and protection against dangerous current levels.

Current & voltage transformers are often used in power distribution systems and industrial plants to ensure safe and accurate measurement of current and voltage. Other areas of use include the following:

Extending the measuring range of an instrument.
Adapting instruments and protective equipment so they can be manufactured for standardized voltages and currents.
When connecting secondary windings to measure sum or difference.
Enabling the use of grounded instruments.

Typical Applications

As a manufacturer of low voltage transformers, we offer solutions for a variety of applications. See the list below.

Small transformers: Signal systems, amplifiers, consumer electronics, etc.
Medium-sized transformers: Lab equipment (with very specific requirements), machine tools, control cabinets, control and regulation equipment, UPS units, matching transformers, etc.
Larger power transformers in the power grid: Distribution transformers, power stations, industrial matching transformers, isolation transformers for marine shore power connections, local transformers (along railways)

Trafo Guide

Things to consider when dimensioning a transformer for your application

Dimensioning a transformer can be quite complicated. Therefore, we at TRAMO ETV have compiled this TRAFO guide which gives you step-by-step tips on what to consider when dimensioning a transformer for a certain type of application.

Basic data (primary/secondary voltage and load power)

Number of primary and secondary voltages som krävs för min tillämpning (man kan ha flera per transformator
Primary voltage (actual voltages across a transformer's primary winding)
Secondary voltage (actual voltages across a transformer's secondary winding)

The temperature in the windings is decisive for how much a transformer can be loaded. Therefore, it is important how well heat dissipation can occur. During intermittent (alternating) operation, with the same load, the temperature does not become as high as during continuous operation. If the time the transformer is loaded is small in relation to the time it is unloaded, the temperature rise will be moderate compared to the rise during continuous load. Due to thermal inertia, the heat emitted will remain constant and a larger part of the stored heat is dissipated, whereby the temperature drops. This means that the transformer can be briefly overloaded.

If you have a high proportion of frequency-controlled applications, such as frequency converters (drives or motor control), these can generate harmonics that lead to losses and can thus affect how the transformer should be designed. Therefore, it is important to inform the supplier about this.

A transformer's rated power is specified at maximum ambient temperature. In cases where the ambient temperature is higher than that, the load must be reduced. Conversely, at lower temperatures, the load can be increased slightly. Therefore, it is important to take into account how the transformer is mounted, for example if it is located adjacent to heat-emitting components or is placed with access to good ventilation.

To achieve effective heat dissipation and reduced losses, the transformer's enclosure and cooling system must be designed to dissipate as much heat as possible from the transformer. The enclosure can be adapted to include cooling air circulation, or alternatively equipped with so-called forced cooling where fans are used to lower the ambient temperature. An important question to ask is the following:

How tight must the enclosure be to meet the requirements of the intended environment? The tighter the enclosure, the worse the cooling, which affects the size of the selected transformer.

Examples of common enclosure classes: IP20, IP23, IP54
Read more about IP enclosure classes here >>>

It is good to know that losses occur in all types of transformers. There are mainly two main types of losses to consider:

No-load losses: magnetization losses, occur when the iron in the magnetic circuit is exposed to an alternating magnetic field. These losses can be described as constant when the transformer is energized.
Load losses: consist of resistive heat losses that occur when current flows through a resistance in the windings, as well as additional losses due to leakage fields around the windings. Load losses change proportionally to the square of the load.

Regardless of the type of loss the transformer generates, it is good to be aware of how these losses affect the ambient temperature. Try to place the transformer in spaces where it affects the surroundings as little as possible.

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