We produce Single-Phase Transformers as Isolating Transformers or Autotransformers with a design power of up to 400,000 VA. The voltage for the in- and output can be up to 1,000 volts (1 KV).
The input voltage and output voltage can be manufactured with or without tapping or additional separate windings on request. As standard in the frequency 50/60 Hz, other frequencies are possible as well. Optionally we also offer the suitable housings as powder-coated steel sheet housings in RAL colors in the protection class IP 23 – IP 65. In addition to DIN EN 61558 – previously DIN VDE 0570 – we also produce Transformers with UL approval.






Bau von Transformatoren - Breimer-Roth

Standards of our single-phase transformers

The following relevant standards are applied in the manufacturing and testing of Single-Phase Transformers: Single-Phase Control Transformers EN 61558-2-2, Single-Phase Isolating Transformers EN 61558-2-4, Single-Phase Safety Isolating Transformers EN 61558-2-6, Single-Phase Autotransformers EN 61558-2-13 and in UL 5085 Low Voltage Transformers (XPTQ2) and UL 1446 Electrical Insulation System (OBJY2). DIN VDE 0570 has been replaced by DIN EN 61558.

Protection classes of our single-phase transformers

We produce our products with the following protection classes according to DIN EN 61140/VDE0140-1

Protection class I (protection by protective conductor):

All electrically conductive housing parts are connected to the protective conductor system of the fixed electrical installation, which is at ground potential. If the equipment is of protection class I, it must have a grounding plug (earthed plug).

Protection class II (protection by protective insulation):

Protection class II devices have reinforced or double insulation between the mains circuit and the output circuit (or metal housing) and do not have a protective earth connection. These devices must not have a grounding-type plug.

Protection class III (protection by protective extra-low voltage):

For these devices, the voltage at the output is max. 50 V AC or 120 V DC (protective extra-low voltage SELV, PELV, FELV). For mains operation, reinforced or double insulation is also required between the circuits (mains). There is no protective earth connection.

Classification of transformers according to the short-circuit resistance

Short-circuit proof means that the temperature does not exceed the specified limits for short-circuited or overloaded transformers and continue to operate after the overload is removed.
A conditionally short-circuit proof transformer is equipped with a protective device that opens the input or output circuit or reduces the current in the event of an overload or short circuit. The transformer is operable again after the protective device is reset or replaced.
A transformer that does not have its own protective device is not short-circuit proof. This protective device must be provided externally to protect the transformer from excessive temperatures.

The fluctuation tolerances in the primary supplied voltage and the associated fluctuations in the rated power are taken into account in all our series in accordance with the relevant standard.

Single-phase transformer geometry and iron cores used

The core of the single-phase transformers, up to a power of 3 kVA, consists of a DIN-EI-Laminations (BS and BE and BEV series) created from grain-oriented or non-grain-oriented transformer core sheet and a coil with at least one primary winding and one secondary winding, depending on the desired power dissipation. For higher powers, we use UI laminations with two coils connected either in parallel or in series (BUH, BUF, BDUS, BSUL series) or our optimized strip sections up to a design power of 400,000 VA (BUVA series).

A special design is the single-phase transformer as a toroidal transformer, which we also produce up to a design power of 3 kVA and freely selectable primary voltage and secondary voltage and the respective current. Here you can adapt the toroidal core more flexible according to the installation situations in height and diameter.

Transforming into AC voltage and DC voltage

In addition to AC voltage, there is also the possibility of transforming an AC voltage on the secondary side for a subsequent DC voltage with defined voltage and current. In principle, the construction of these power supplies is the same as for single-phase transformers with a core and coil(s), each with at least one primary winding and one secondary winding, additionally with rectifier and heat sink. On request also without capacitors and with a certain residual ripple.

By using different manufacturing techniques in our company, we are able to optimize the magnetic flux in the iron core and thus significantly reduce the power losses in no-load operation as well as in continuous operation.

The following series are available:

  • BS – Control Transformers with fixed voltage combination: primary 230 V or 400 V with +/- 5% and an output voltage with 24 V or 230 V power up to 3,000 VA.
  • BE – construction power up to 3,000 VA, primary voltage and secondary voltage freely selectable.
  • BSV and BEV are the loss-optimized variants of BE and BS.
  • BSUS/BSUL – Control Transformers in vertical or horizontal design with fixed voltage ratio and power ratings up to 20 kVA.
  • BUF – Single-Phase Transformers up to 25 kVA with insulation class F, BUH – up to 315 kVA in insulation class H, voltage combinations freely selectable.
  • BUVA – loss-optimized series up to 400 kVA, voltages are freely selectable.

Further special designs such as construction site Insulation Transformers or Transformers for operating room lights and for medically used rooms etc. are listed here.