Power Electronics

High-power Resistor Protects Motors

Aimed at motion control applications, the PWHW Series of high-wattage power resistor assemblies feature an optional inline circuit protection device designed to prevent motor damage caused by overheating in a stall condition. Offered by the TT electronics IRC Wire & Film Technologies Division, these resistor assemblies consist of a 115-W rated wirewound resistor encapsulated in a flameproof housing with an inorganic fill material, which gives the assembly a high thermal mass.

“Initially developed as a voltage dropping resistor for daylight running lamps and cooling fan motor speed controls, the PWHW Series resistors have been field-proven in the harsh underhood environments and high temperatures found in automotive applications,” says Wilson Hayworth, product manager for IRC’s Wire & Film Technologies Division. “An extremely reliable part, the PWHW Series has seen more than 15 million units deployed in the field under these kinds of conditions, without a single warranty return.”

The assemblies can be ordered with an automatic resettable circuit breaker attached to the lead wires of the wiring harness. The breaker opens during a motor stall condition such as when an obstruction or overload condition prevents the motor from rotating. The breaker remains open until power to the system is reset.

The PWHW Series resistors offer typical resistances ranging from 0.100 Ω to 10.00 Ω with ±5% tolerance. Package ratings are 30 W, 45 W and 115 W for continuous operation at 125°C. Typical pricing is $5 each in quantities of 1000.

For more information, visit www.irctt.com.

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