PR resistors are moderate-power thick film resistors with a compact design. They have negligible inductance and large creepage dimensions which makes them very suitable for filter and snubber applications.
All materials used for resistor construction are UL94V-0 listed. During manufacturing of the resistors, an electrically conductive paste is printed on an alumina ceramic substrate. The electrical connections are tin-welded to the thick film through copper wire.
Three mechanical sizes and more than 10 housing types are available. Up to three resistors can be included inside a single housing. Power ratings for PR resistors range from 100 to 800 W. The nominal power is dependent on the temperature of the heatsink. Higher temperatures lead to linear derating.
The maximum working voltage for PR100 resistors is 1500 VAC. The maximum working voltage for PR250/PR600/PR800 resistors is 5 kVAC. Depending on the resistance, the resistors can handle up to four times the nominal power rating for 10-second pulse/120s. Danotherm can provide metal thick film resistors for applications with higher overload requirements.
Using a heatsink of sufficient size with the PR series resistors is necessary. Thermal grease or thermal conducting foils must provide good thermal contact between the insulated resistor base and the heat sink.
The standard tolerance is ±10%, and resistors with ±1% tolerance are available on request. High-voltage cable terminals are available as options for PR250 resistors.