Introduction to the use of transformer switching relays TSR
Transformers with a small or no air gap in the core, such as toroidal transformers, cause high inrush currents and cannot be protected on the primary side even with fuses designed for several times the rated current. The primary-side fuse trips (almost) every time the transformer is switched on.
With a transformer switching relay, -TSR-, transformer switching relay, which is connected between the mains input and the transformer, the rush effect and fuse tripping can be reliably prevented in all cases, because the inrush current is completely eliminated.
Function of TSRL and TSRLF
Targeted influencing of magnetization in the iron core
The function of the TSR switch-on method for single-phase transformers essentially consists of the targeted influencing of the magnetization in the transformer iron core with unipolar voltage sections, which are “cut out” of the mains voltage. The magnetization is brought to maximum remanence and then switched on in antiphase at zero crossing.
TSR function: the transformer is pre-magnetized with unipolar voltage time surfaces until the remanence is at the maximum point, then switched on fully and bridged with a relay contact in the case of TSRL, fully switched on with a semiconductor switch in the case of TSRLF and bridged with a contactor contact if necessary.
Pre-magnetize transformer, avoid inrush current, best possible transformer switch-on,
Inrush current cannot occur
Transformer response to voltage dips, important for compliance with medical device standard EN60601-1-2
Short voltage dips, so-called voltage dips, can saturate transformers depending on their phase position, so that a high current is drawn from the transformer after the voltage dip and the primary fuse trips. A TSRL completely prevents the fuse from tripping. According to the EMC standard: EN 60601-1-2, medical devices are tormented with voltage dips lasting 10 msec. Without TSRL upstream of the mains transformer, the fuse is tripped and the test is not passed.
A voltage dip, upper curve, of only 5 msec. brings the transformer into saturation and provokes a current surge, lower curve. (When the positive and negative voltage time surfaces, which transport the magnetization in the iron, are no longer symmetrical for a short time). The high current causes the fuse to blow immediately, as can be seen here from the voltage dip.
Voltage dips cause transformers to saturate when the positive and negative voltage time surfaces are no longer symmetrical for a short time. A TSR prevents saturation from occurring.
Comparison of inrush current limiter, dimmer and transformer switching relay.
Comparison of 16 different switch-on methods
Transformers can be switched on directly, which has disadvantages.
If you use inrush current limiters or avoid the inrush current altogether because you switch the transformer on via transformer switching relays or if you even switch the transformer on with an auxiliary winding without inrush current, there are some advantages.
Comparison of transformer switch-on options
- 01-Trafoschaltrelais-Vergleich-m-ESB s.pdf
- 02-Vergleich-Groesse-ESB-mit-TSRL.PDF
- 03-Scheitelschalter-auf-Trafo-Schaltplan.PDF
- 04-ESBauf-Ringkerntr.-10AB-Sich.PDF
- 07-Ringkerntrafo-mit-ESB-oder-TSR.PDF
- 08-Trafosoftstart Leerl-ELR-Dimmer.pdf
- 09-Trafostart-Ringkern-m-Last-mit-Dimmer.PDF
- 00-Einschalt-Varianten-einphasen-Trafos-UEbersicht.pdf
- 05-Einschalten-1kVA-einphasen-Trafo-UEbersicht.pdf
various inrush current limiters, none of them can handle voltage dips and require cool-down pauses between switching on. They are also not short-circuit proof.
An inrush current limiter for 32A, shown on the rail on the left, a transformer switching relay for 32A, shown on the rail on the right.
Heating the house with electricity
- Dampfsperre oder nicht.pdf
- Lupotherm versuche-5.pdf
- Lupotherm versuche-5.pdf
- Tsrl-apl-fussbodenheizen-m-devi-regler-05e.PDF
- Tsrl-apl-fussbodenheizen-m-eberle-regler-06.PDF
- Tsrl-apl-fussbodenheizen-m-univ-regler-10.pdf
- Wärmedaemmung unter Heizfolien und mehr.pdf
Electric wall panel heating can be economical for well-insulated rooms and walls.
Transformer physics and calculation, see under interesting facts
The voltage time surface drives the induction along the hysteresis curve.
The hysteresis curve describes the course of the magnetization in the iron core. The voltage time domain, the integral of the voltage under the sine curve, drives the induction in the iron core along the hysteresis curve.
All PDF documents are only available in German