Crowbar resistors are used to protect the outputs of power sources in railway systems against the short-time (transient) and long-time overvoltage failures.
Description
Output voltage rises very fast (in microseconds) when semi-conductors of power source fail (short circuit) or the control circuit collapses. Protection system fully independent from the control system of power source detects the fast increase of the output voltage and switches the crowbar resistor connected to the power output with the semi-conductor switching system. In this case, crowbar resistor create an over current limited to a value that will not damage the power supply but will activate the protection equipment such as fuses and circuit breakers and attenuate the over voltages very quickly.
There are two different types of crowbar resistors. It can be defined as ‘soft crowbar’ to suppress short-term voltage spikes and ‘hard crowbar’ to eliminate longer-term overvoltages. The most important technical feature is that it has a special structure that can absorb very high powers in a very short time.
Advantages
- Light and compact design
- Fast cooling
- Long-lasting mechanical and electrical design
- High energy absorption in a short time
- Resistance material with the least resistance change with temperature
Applicaiton Areas
- High-Speed Trains
- Locomotives
- Wagons
- Electrical Busses
