Boone, N.C. Adapting a proven automotive technology for industrial and commercial applications, such as motion control, a new rugged, high-wattage power resistor assembly from TT electronics IRC Wire & Film Technologies Division delivers a space savings package for voltage dropping, surge, or over voltage protection. The series also features an optional in-line circuit protection device designed to prevent motor damage from overheating in a stall condition.
Designated as the PWHW series, the assemblies consist of a high-wattage power wirewound resistor encapsulated in a flame-proof housing with an inorganic fill material, giving the assembly a high thermal mass. The resistors carry a typical resistance range of 0.100 ohm (Ω) to 10.00 Ω, with a ±5% resistance tolerance. Package ratings are 30 W, 45 W and 115 W for continuous operation at 125°C. Custom specifications are available.
The PWHW devices were initially developed as a voltage dropping resistor for daylight running lamps and cooling fan motor speed controls, and have been field-proven in harsh under-the-hood environments and high temperatures found in automotive applications. The company also notes that there hasn't been a single warranty return with more than 15 million units deployed in the field under these conditions.
The heart of the assembly is IRC's PWHW series resistor, a 115-watt device, which can be used to provide a dual-speed system for single motor drives in industrial applications. Employed as a dropping resistor, it reduces the speed of the motor by lowering the operating voltage, creating a high and low speed system as the resistor is switched into or out of the circuit.
The assemblies can be ordered with an automatic resettable circuit breaker attached to the lead wires of the wiring harness. How it works: The circuit breaker opens during a motor stall condition such as when an obstruction or overload condition prevents the motor from rotating. The circuit breaker will open when the current reaches a specific amperage, and remains open until the obstruction is removed and the power to the system is reset to prevent motor damage.
Typical pricing for the PWHW series resistors is $5.00 each in quantities of 1,000. Delivery is six to ten weeks.
IRC, 1-361-992-7900, www.irctt.com