Isolating transformer

The isolating transformer or isolating transformer according to the DIN EN 61558-2-4 VDE 0570 standard is a transformer with protective separation – galvanically isolated – between the input voltage and the output voltage.

An isolating transformer is a static device that uses at least one primary winding and one secondary winding to convert AC voltage and AC current at the same frequency of 50 Hz or 60 Hz into a different system of voltage and current by means of electromagnetic induction. The term transformer or isolating transformer is often used here. The power rating is expressed in VA or kVA (VA stands for volt-ampere and is the unit of measurement for apparent electrical power, kVA for kilovolt-ampere).

A transformer consists of a magnetic circuit, known as the core, and has at least two windings through which current flows. The winding facing the electrical voltage (mains voltage) is called the primary side, the side with the consumer and the electrical load is called the secondary side. The manufacturing technology for the core and the quality of the transformer core used have an effect on the magnetic circuit. Ideally, the magnetic circuit (magnetic field) should generate low eddy current losses and have low remagnetization losses (hysteresis losses). We only use copper for the winding.

With the exception of silver, copper has the best conductivity value with γ = 56, while aluminum only has γ = 36. Aluminum follows with a gap of around 35 percent. Copper is therefore the best metal and aluminum “only” the second best of the technically and economically usable conductor materials. All other metals cannot be considered as conductors and alloys generally have a considerably lower conductivity than pure metals. Silver or gold are ruled out due to their high price. Aluminum is a light metal with only about 35 percent of the density of copper. Isolating transformers can be designed as single-phase or three-phase transformers with different switching groups. For three-phase transformers – also known colloquially as three-phase transformers – Breimer-Roth GmbH uses the Dyn 5 switching group as standard. Here the star point is fully loadable. Other switching groups are available on request. Isolating transformers can be designed as control transformers or safety transformers.

The isolating transformer usually has a winding on the input side that is adapted to the existing mains voltage, possibly with the option of compensating for deviating mains voltages of 230 V or 400 V by means of taps. The output voltages can be selected as required. Different voltages with different currents can also be provided on the secondary side as additional separate windings. A PE protective conductor is provided to protect against electric shock. Our transformers are all Made in Germany.

Please note that isolating transformers are not used to convert frequencies (Hz). If you require a frequency conversion, we will be happy to provide you with a customized offer.

The use of isolating transformers in accordance with EN 61558-2-4 VDE 0570 is necessary where reliable protective separation of circuits is required for the purpose of safety against electric shock. The isolating transformer can be manufactured for fixed installation or for mobile use with a portable enclosure in protection class 1 or protection class 2. In the case of housing installation, a supply cable and sockets can also be provided on request as a socket outlet with earthing contact or CEE socket and additional fuse protection can be installed.

An AC voltage not connected to earth is generated on the secondary side (important: secondary side must not be earthed).

When connecting two devices to the transformer, ensure that both housings are connected to the same floating potential. Technical data must always be found on the rating plate.