Useful Accessories

Crowbar Thyristor

The Crowbar Thyristor is a stand-alone protection of dc-link converters against overvoltages. It monitors the dc-voltage and triggers a thyristor at a predetermined voltage. Connected to the dc-link and an external resistor, it discharges the dc-link immediately at overvoltages and protects the sensitive and expensive IGBTs of the converter dependably. In addition, the unit has a galvanically-isolated-electrical and an optical interface. The electrical interface offers an 24 V in- and output. If the user wants to trigger the unit manually or automatically by a control-unit, one just has to apply a 24 V pulse to the input port. The electrical output has an open collector. In normal operation, the output is pulled down. When the thyristor has been fired, the output will become high impedance for 50ms. This offers a feedback path to the superior control-unit. The optical interface is realized by fiber optics. A light pulse at the input will trigger the discharge process. To get a cable-break protected system, the optical output is inverted. In normal operation the transmitter flashes. After firing of the thyristor or at a non-supplied unit, the transmitter is turned off.

Nominal Data
VDC,trip,max 1100 V
i(t)² dt max 900 kA²s
ipeak 1300 A
power connection wire cross section ≤ 10 mm²; screw terminals
supply 115Vac / 230 Vac IEC C14
size 175 x 120 x 235 mm
weight 1.5 kg

Crowbar Thyristor
Crowbar Thyristor [back view]