Failsafe Moulded Wirewound Resistors

The unique feature of this series of wire wound resistors is their case size. To make more compact resistors, IRC developed the BWH series and the BWF series which are rated at 2 watts, however they're encapsulated in a 1 watt case size. The same applies for the BW20 series and the BW20F series which are rated at a 1 watt rating encapsulated in a ½ watt case size.

Case sizes:

• SPH/SPF/BWH/BWF
• SP20/SP20F/BW20/BW20F

Note: After IRC was bought out by TRW/TT Electronics the BWH, BWF, BW20 and the BW20F series were discontinued. TRW/TT Electronics released a new series of resistors that serve as drop in replacements for the older series. To cross reference the older series to the new series click here.

1.Resistive Element:
Every type of wire wound resistor has a resistive alloy winding on a braided fiberglass substrate. To increase processibility and protect the resistive element, these resistors are coated in a silicone coating.

2.Encapsulation:
This type of resistor is encapsulated in a compressed molded phenolic plastic material. Any part number ending with the letter “F”, simply means that there is a flame retardant coating applied to the resistive element. Which provides flammability protection when a destructive load may occur.

3.Termination:
This series of wirewound resistors are terminated using a copper flashed steel lead with an alloy coating, which is then welded to a cap made out of the same material.