Raleigh, N.C. Stackpole Electronics, Inc. offers a series of UL and CSA approved wirewound resistors with an integrated thermal fuse. The RWT series wirewound resistor incorporates a 2-amp thermal fuse in a standard 5-watt vertical mount ceramic case.
The RWT 2-watt devices are housed in a 25 (H) x 13 (W) x 9.5-mm (D) package. The series is available in E24 resistance values from 1 to 100 ohms with a 5% resistance tolerance. The rated functioning temperature of the thermal fuse is 142°C but other thermal fuses are possible, said the company.
The integration of these two devices as well as the UL (Akaneohm file no. E255350) and CSA (Akaneohm file no. 229946) approvals provide both the resistor characteristics that power supply designers need as well as the safety features they require in a single device, said Stackpole. This allows designers to reduce component count and board space, which will enable them to downsize current designs or add additional features to future products.
The RWT devices are resistors that behave like slow blow resettable fuses. Once the power dissipation through the part causes the heat generated to exceed 142°C, the part opens and stops the current flow, said Stackpole, and once the circuit cools down sufficiently, the part returns to its original state. This is in comparison to a fusible wirewound resistor which is a one-time only fusing device, and PTC thermisters, which only limit current flow and are rarely UL recognized, said the company.
Pricing: Typical pricing for the RWT 2 is $0.25 each in minimum quantities. It comes in standard bulk packaging of 1,500 pieces per box.
Availability: Standard lead time is eight weeks.
Product information: wirewound resistors
Stackpole Electronics, 1-919-850-9500, www.seielect.com