Electronic Components Blog

Wednesday, 24 September 2014 14:09

Pulse - Surge Capability of Resistors


Due to existing needs, many modern electronic circuits and apparatus experience transient pulses and surges. This in turn has led to the need to "design in" transient surge protection especially in circuits like motor controllers.

When a motor starts, the current drawn at this point is excessive and can cause failure in resistors. Similarly if capacitors are used for motor starting, the current – limiting resistors in the circuit experience very high overloads during the capacitor charge / discharge cycles.

At this point it is pertinent to mention that while there is a plethora of information available on this subject for active devices like semiconductors, passive devices such as resistors are often neglected and their role in withstanding transient pulses/surges is not yet fully grasped by the designer.

Since resistors are often located in areas likely to experience transient pulses / surges, it is indeed critical for the designer to be fully aware of this phenomenon and design in the correct resistors for his particular application. HTR has worked closely with designers to produce custom built resistor solutions for specific protection applications and a summary of information / data obtained over the years is now given in the attachment for the benefit of the design engineer.