GLOSSARY

Isolating Transformer

Definition of an Isolating Transformer

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

Function of an Isolating Transformer

An isolation 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 50 Hz or 60 Hz into another system of voltage and current by electromagnetic induction. The term transformer or isolating transformer is often used here. The construction power is expressed in VA or kVA (VA is the term for voltampère and stands for the unit of measurement of apparent electric power, kVA for kilovoltampère).
A transformer consists of a magnetic circuit, called 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, and the side with the consumer and electrical load is called the secondary side. The manufacturing technique for the core and the quality of transformer core used affects the magnetic circuit. The magnetic circuit (magnetic field) should ideally produce low eddy current losses and have low remagnetization losses (hysteresis losses). We use only copper for the winding.

Except for silver, copper has the best conductance with γ = 56. Aluminum, on the other hand, has only γ = 36. Aluminum thus follows with a gap of about 35 percent. Thus, copper is the best metal and aluminum “only” the second best of the technically and economically usable conductor materials. All other metals cannot be considered as current conductors, and alloys generally have considerably lower conductivity than pure metals. Silver or gold are not suitable because of their high price. Aluminum is a light metal with only about 35 percent the density of copper. Isolating transformers can be created as single-phase or as three-phase transformers with different vector groups. For three-phase transformers – the Dyn 5 vector group is set as standard at Breimer-Roth GmbH. Here the star point is fully loadable. Other vector groups are possible on request. Isolating transformers can be designed as control transformers or safety transformers.

Construction of an Isoltaing Transformer

The isolating transformer usually has a winding on the input side adapted to the present mains voltage, optionally with the possibility of compensating differing mains voltage of 230 V or 400 V by tapping. The output voltages can be selected as required. Different voltages with different currents can also be provided on the secondary side as further separate windings. A PE protective conductor is provided for protection against electric shock. Our transformers are all Made in Germany.

Application Areas of an Isolating Transformer

The use of isolating transformers according to 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 portable use with housing portable in protection class 1 or protection class 2. In the case of housing installation, a supply line and sockets can be provided on request as a protective contact socket 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, make sure that both housings are connected to an ungrounded equal potential. Technical data must always be found on the type plate.