Technical Description
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Tapped Transformers
General
Tapped transformers are autotransformers that allow you to gradually adjust the speed of disc-type
motors, such as those that are commonly found in ventilation appliances. With disc-type motors, it is
possible to control the speed over the supply voltage height.
The tapped transformers are equipped with a series of continuous winding taps. These taps make it
possible to control the speed of the fan motors in small steps. The speed is switched by means of a
tap changer in the control device. In principle, each tap can be loaded with the full nominal current
associated with the relevant types. This transformer is designed for a constant current.
Our single-phase tapped transformer range includes all our standardised types for the 1.5 A – 17.5 A
performance range, an input voltage of 230 V and the following output voltages: 80 / 100 / 125 / 150 / 175 /
200 / 230 V, as well as a frequency of 50 / 60 Hz.
Our three-phase tapped transformer range includes all our standardised types for the 2.2 A – 19.0 A
performance range, an input voltage of 3 x 400 V and the following output voltages: 190 / 240 /
295 / 350 / 400 V, as well as a frequency of 50 / 60 Hz.
The following series are available
SFTE
These single-phase tapped transformers are suitable for the 1.5 – 4.2 A performance range.
The special coil body made completely of plastic and with integrated terminal chambers and
fixing bracket was developed and is produced by Frei. The coil wires are fed directly to the
terminals along plastic channels, thus ensuring protection against direct contact. In addition,
blade-type terminals measuring 2.8 x 0.8 mm and conforming to DIN 46 244 are attached to
the screw contacts. The captive screws featuring self-lifting thrust washers that are attached
to the contacts have a combined cross recession/longitudinal slot. A replaceable thermal
fuse can be installed in the coil body on request.
STEBL
This type of single-phase tapped transformer is suitable for the 7.5 – 17.5 VA performance
range. The coil wires are routed to compact modular transformer terminals, which can also
be equipped with slotted 6.3/2.8 mm tab connectors.
Subject to change without notice | Version of 01 15
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Gebrüder Frei GmbH & Co. 72461 Albstadt Germany
Technical Description
DTL /
DTBL www.frei.de
These three-phase tapped transformers are suitable for the 2.2 – 19.0 A performance range.
The coil wires are routed to terminal blocks. These transformers are only available in a flat
version for wall mounting. To ensure good heat dissipation for the performance levels involved, type R1,0 transformers and higher feature a vertical air duct. The three-phase
tapped transformer is of a Yna0 vector group design.
Special versions
We can of course provide other winding taps, different voltages or thermal fuses. Other terminal types
(such as spring-loaded terminals) can be installed instead of the modular transformer terminals.
On request, we can produce transformers with different frequencies and other electrical properties such
as smaller losses, smaller voltage drops or higher insulation classes.
Gebrüder Frei GmbH & Co. 72461 Albstadt Germany
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Subject to change without notice | Version of 01 15