Development and production of inductive winding goods
Since 1932 – specialists for small, large, and 0 series
Development and production of inductive winding goods
Since 1932 – specialists for small, large, and 0 series
Technology
Inductances for every requirement and every application. Top quality and high reliability – made in Germany!
On this page we have compiled a wealth of useful information, technical data and specifications on our transformers and inductances.
As passive components, transformers and inductances may appear to be simple products in the broad field of electrical engineering. However, this is deceptive because they are more complex in function and design. This is why you will find extensive information on the various types of protection, protection classes and insulation classes as well as an overview of our certificates in the Technology section.
Here you will also find additional information on installation heights and installation positions, maintenance information and what to bear in mind when using the inductances we manufacture outside Europe. We also explain questions from the world of transformers and inductances in general terms. You can find all this and much more here.
To find out even more about our products and how they work, take a look at our videos explaining our products.
Our contacts will also be pleased to answer any technical questions you may have.
Technical
reference book
We use selected, high-quality materials for our production. The windings of the bearing transformers are made of copper, the coil formers up to approx. 10 kVA are generally made of plastic. Larger outputs are mainly manufactured with self-supporting windings.
For almost all bearing types above 100 VA, the inrush current peak has been reduced by structural modifications.
We achieve greater dielectric strength, longer service life, better moisture protection and lower inherent noise levels for smaller transformers through electro-varnish impregnation, and for power ratings above 100 VA partly through vacuum impregnation with impregnating resin. Transformers can also be encapsulated in plastic housings, special transformers, such as high-voltage transformers, in a reusable mold with resin encapsulation (full encapsulation).
To manufacture a high-quality product, our technicians use computer calculation programs. Based on these calculations, we can compare and coordinate the power losses of sheet metal and copper, temperatures in the open circuit or steady state, short-circuit voltages, voltage drop, inrush current, open circuit current, copper quantity and sheet metal quality before production begins.
The use of high-quality and expensive raw materials is kept to a minimum, without reducing the quality of the transformer. This results in advantages in terms of energy consumption and, thanks to the reduced use of materials, also saves on the subsequent disposal of the transformers.
When ordering autotransformers, please always specify the throughput power. The output voltages specified on the rating plate are achieved when the transformer is loaded with rated power and the power factor cos j = 1.
It should be noted that the output voltage increases at low power consumption. The increase is inversely proportional to the power draw. With small transformers in particular, the actual output voltage can therefore be significantly higher than the rated output voltage.
For control transformers, the short-time power is also specified in the catalog at the power factor cos j = 0.5, whereby the voltage must not fall more than 5% below the nominal output voltage. Our control transformers have a high short-time power.
Please also note that in accordance with the applicable VDE, EN or IEC regulations, the phase-to-phase voltages are specified for the input and output voltages of three-phase transformers. The phase conductor voltage is the voltage that is present between the 3 phase conductors.
Please specify the circuit types: e.g. YY0 or YY6, DY5, DY11, YD5, YD11, DZ0, DZ6, YZ5, YZ11. If no details are given, we usually manufacture the transformers in YY0 or DY5.
With YYN0 and YYN6, the secondary star point may only be loaded with a maximum of 10% unbalanced load if the primary star point is not connected to the mains. With a higher unbalanced load, either a primary delta connection or a secondary zigzag connection must be used.
Unless otherwise specified, our transformers are designed for one input and one output voltage. Apart from autotransformers, the input and output voltages are galvanically isolated and tested at a high voltage equal to or higher than that specified by VDE regulations. Control transformers also have two taps on the input side, generally +-5%.
In the case of universal control transformers, two separate input windings are connected in parallel or in series in accordance with the printed connection diagram. As a result, the size is similar to transformers with the same winding and only one input voltage, but 32 different input voltages between 200-600 volts can be connected.
Of course, the supplementary provisions of the aforementioned VDE regulations or additional VDE regulations are observed for special transformers.
The classification of thermal classes has been revised in accordance with the new VDE regulation EN61558. It is based on an ambient temperature that normally does not exceed 25°C, but can occasionally reach 35°C. Most transformers are installed with other devices in switchgear cabinets, machines or electrical systems. In this case, the conditions are different from those for a transformer approved for IP 00, so that VDE regulation 61558 is no longer valid.
We are also happy to manufacture transformers for you according to the regulations of other countries, e.g. SEV, CSA, UL, or according to the regulations of the shipping industry. We are also able to manufacture transformers that are operated at a higher ambient temperature, for example 60°C or 70°C for systems in tropical areas.
The operating frequency of the transformers is 50 Hz. Provided there are no aggravating conditions, they can also be operated at 60 Hz. For installation at locations more than 1,000 m above sea level, please consult us or refer to the following table:
Unless otherwise specified, our transformers are designed for continuous operation (DB). In intermittent operation (AB), the duty cycle is calculated as follows (cycle time according to VDE ≅ 10 min):
Example: A transformer is fully loaded for 2 minutes. This is followed by a break of 8 minutes (cycle time 2 on / 8 off ≅ 10 min):
Extract from DIN 42404:
Connections of small transformers are marked numerically and alphanumerically in accordance with DIN 42404. To ensure the correct connection to a power source or a network or the correct connection of a load, a unique assignment of the connection voltages to the numerically marked connection points must be specified.
Single-phase transformers
According to EN61558-2-1, transformers with more than one rated input or rated output voltage must be labeled to indicate the rated voltages of the individual terminals. We label the terminals with the nominal voltages to ensure unique assignment. The assignment of input and output voltage is determined by the rating plate.
Example:
Three-phase transformers
In accordance with DIN 42404, the connection designation is made up of groups of numbers and letters (e.g. 1U1, 1V1, 1W1).
The connection designation is broken down as follows:
Connection designation >1 U 1<
>1< First number = identification of the winding where, (1) identifies the input winding.
>U< letter = identification of the connection, U on L1, V on L2, W on L3 N on N
>1< Second number = identification of start, end, tap of the winding. This number is omitted for windings without taps with an interconnected star point.
The assignment of the connections must be uniquely indicated. According to EN 61558-2-1, transformers with more than one rated input or rated output voltage must be labeled with the rated voltages of the individual terminals. We label the terminals with the nominal voltages to ensure unique assignment. The assignment of input and output voltage is determined by the rating plate.
Example:
Transformer with a primary and secondary winding galvanically isolated:
Transformer with one primary winding and two taps and one secondary winding galvanically isolated:
Please note that, depending on the voltage ratio between the primary winding and the taps, a larger winding space is required. This requires a larger transformer type.
Transformer with a primary winding and a secondary winding with galvanically isolated taps:
Please note that unless otherwise specified by you, the rated secondary current is calculated by dividing the power by the highest secondary voltage.
Transformer with one primary and one secondary winding galvanically separated, in which the primary or secondary winding is separated so that a series or parallel connection can be made:
Transformer with a primary and secondary winding electrically isolated and a protective winding between the primary and secondary:
A protective winding is required to attenuate harmonics from primary to secondary or from secondary to primary as far as possible, or for transformers according to VDE 0107 – transformer with an autotransformer winding:
Caution: There is no electrical isolation between the primary and secondary windings. Both are conductively connected to each other. The autotransformer winding is characterized by a lower type power than the throughput or rated power. The autotransformer is mainly used where the mains voltage (phase-to-phase voltage) and the voltage of the appliance to be connected do not match. The type power is calculated using the following formula:
Example: Transformer rated power 1000 VA, upper voltage 230 V, lower voltage 115 V
Protection class I : Transformer with PE connection
Protection class II : Transformer with double insulation without PE connection
Protection class III : Safety extra-low voltage
Portable transformers must be either absolutely or conditionally short-circuit proof. Only transformers with very low power ratings can be manufactured economically with absolute short-circuit protection. Larger outputs are therefore conditionally short-circuit proof, i.e. generally fitted with a primary fuse. However, this protection is not easy to implement, as current peaks in the order of ten or more times the rated current can occur when transformers are switched on.
It goes without saying that the built-in fuses must not respond, even when switched on at unfavorable times. Therefore
the fuse current must be selected to be higher than the rated current. Nowadays, however, only motor-protective circuit-breakers with transformer characteristics make sense.
As a rule of thumb, transformers should be protected with slow-blow fuses, or at least with medium-slow-blow fuses on the primary side. The rated fuse current should be approximately 1.8 to 2.5 times the rated primary current. A glass tube fuse is recommended for smaller rated fuse currents.
Such a device can be protected by an external protective device appropriate to its intended use. When connecting the transformer to the mains and connecting a load, a protective device such as a fuse, overcurrent switch or similar, rated for the currents occurring during operation, must be subsequently installed in the supply or discharge line.
Conditionally short-circuit-proof transformer
A conditionally short-circuit-proof transformer is a transformer with an attached or integrated protective device that protects the transformer from destruction in the event of a fault. Possible protective devices include fuses, overload triggers, thermal fuses, temperature limiters, PTC thermistors, circuit breakers, etc.
Transformer must be short-circuit-proof
An absolutely short-circuit-proof transformer is a transformer that can be operated in short-circuit mode without the transformer being destroyed in any way. Once the short-circuit has been removed, the transformer can continue to be operated normally.
Get to know our product variety from A to Z:
| – 4-wire sine filters |
| – Active filters |
| – Active harmonic filters |
| – Anode transformer |
| – Matching transformer |
| – Matching transformer |
| – Defrost transformer |
| – Output / motor choke |
| – Output choke |
| – Automatic voltage stabilizer |
| – Battery buffering for mains modules / switching regulators |
| – Sheet metal windings (Al. and Cu.) |
| – BuStrom D three-phase |
| – BuStrom DP 12-pulse |
| – BuStrom E single-phase |
| – BuStrom E1/E2 |
| – Large three-phase transformer in the high power class |
| – Large three-phase transformer in the medium power class |
| – Three-phase power supply |
| – Three-phase transformer for PCB mounting |
| – Three-phase transformer with attached rectifier |
| – Three-phase transformer with rectifier and heat sink |
| – Three-phase transformers |
| – Three-phase transformer for emergency power generators |
| – Three-phase transformer for medium power class |
| – Three-phase commutating choke |
| – Three-phase mains choke |
| – Three-phase mains choke, water-cooled |
| – Three-phase mains regenerative choke Three-phase mains return choke |
| – Three-phase isolating transformer for rooms used for medical purposes |
| – Three-phase du/dt filter 400V 50Hz |
| – Three-phase du/dt choke |
| – Three-phase du/dt filter |
| – Three-phase mains filter |
| – Three-phase sine filter 400V 50Hz |
| – Three-phase sine filter 400V 100Hz |
| – Three-phase sine filter 400V 200Hz |
| – Three-phase sine filter 400V 300Hz |
| – Chokes |
| – du/dt chokes |
| – EI core transformers |
| – Single-phase inrush current limiter |
| – Single-phase large transformer in the high power class |
| – Large single-phase transformer in the medium power class |
| – Single-phase safety transformer |
| – Single-phase economy / US transformer |
| – Single-phase transformers |
| – Single-phase isolating transformer for rooms used for medical purposes |
| – Inrush current limiter for three-phase transformers |
| – Inrush current limiter for single-phase transformers |
| – Electrical filters |
| – Electronics |
| – Electronic power supply units |
| – Electronic transformers |
| – EMI filters |
| – EMC-resistant transformers |
| – Decoupling transformers |
| – Ferrite core power transmitter |
| – Ferrite core transformers |
| – Damp-proof transformers (wet room transformers) |
| – Filters |
| – Filter circuit choke |
| – Shaped coils (form coils) |
| – Radio interference suppression choke |
| – Galvanizing equipment |
| – Cast resin transformers |
| – Smoothing choke |
| – Rectifiers (rectifier devices) |
| – Rectifier transformer |
| – DC voltage supply |
| – GREENLINE control transformer (different paint colors possible) |
| – Hand lamp transformer |
| – Harmonic filters |
| – Heating transformer for induction heating |
| – Heating transformer for secondary potentials |
| – High-voltage test transformer |
| – High-voltage coils |
| – High-voltage transformer (vibration-proof) |
| – High-voltage transformer |
| – High-current transformer |
| – Pulse transformers |
| – Low-capacitance isolating transformer |
| – Small chokes |
| – Low voltage supply stabilized BN 24 V |
| – Low voltage supply stabilized FN 12 V |
| – Low voltage supply stabilized FN 24 V |
| – Small transformers |
| – Combi filters |
| – Commutation choke |
| – Constant holder |
| – Coupling inductances |
| – Laboratory transformer |
| – LCL filters |
| – Printed circuit boards |
| – Soldering transformer |
| – Air-cooled transformer |
| – Air coil |
| – Air coil – low-noise choke |
| – Magnetic voltage stabilizer |
| – Sheath core transformer |
| – Medical transformer |
| – Multi-voltage transformer |
| – Message module (reporting module) |
| – Medium-voltage transformer |
| – Motor chokes for high-speed spindles |
| – Three-phase mains choke, water-cooled |
| – Mains choke |
| – Mains filters |
| – Power supply units |
| – Clocked network modules |
| – Mains transformers |
| – Low-voltage transformers |
| – Harmonic filters with automatic impedance control |
| – Harmonic frequency filters |
| – Passive filters |
| – Passive harmonic filters |
| – PM core transformers |
| – Primary switching regulators |
| – Three-phase primary switching regulators |
| – Single-phase primary switching regulators |
| – Print transformers El open |
| – Print transformers El potted |
| – Print transformers Ul potted |
| – Test equipment |
| – Test transformers |
| – Buffering in the event of a power failure |
| – Regulating transformers |
| – Toroidal transformers |
| – Suction chokes |
| – Shell core transformers |
| – Switching regulators |
| – Cutting band core transformers |
| – Protective transformers |
| – Welding transformers |
| – Oscillating transformers |
| – Safety transformers |
| – Sine filters |
| – Special products |
| – Special transformers |
| – Autotransformer |
| – Special transformer |
| – Toy transformer |
| – Stabilization module |
| – Standard transformers |
| – Plug-in core transformer |
| – Control units |
| – Control transformer 60VA – 6,300VA |
| – Control transformer |
| – Fault signaling modules for primary switching regulators |
| – Interference protection transformers |
| – Power supplies |
| – STS transmitter |
| – Step transformer |
| – Audio frequency and ripple control products |
| – Audio frequency suppressors Audio frequency gate |
| – Toroidal choke |
| – Transductor |
| – Water-cooled transformer |
| – Transformers |
| – Transformer with high-current windings |
| – Transformer voltage stabilizers |
| – Isolating transformer |
| – Transitions |
| – UI core transformer |
| – Reversing choke |
| – Universal control transformer 100VA – 2,500VA (UL-Iso-System) |
| – UPS systems |
| – Fan transformer with V-circuit |
| – Fan transformer VT230 |
| – Fan transformer VT400 |
| – Distribution transformer |
| – Pre-charging transformer |
| – Series chokes |
| – Series transformer |
| – Transducer |
| – Water-cooled transformer |
| – Weatherproof transformer |
| – Ignition transformer |
| – Twin-chamber isolating transformer Dual-chamber isolating transformer |
| – Twin-point link reactor Two-point intermediate circuit choke |
| – Link reacor |
Data and dimension sheets
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