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About Our Wirewound Resistor Portfolio

Wirewound resistors are the preferred choice for applications requiring high continuous power dissipation, exceptional surge capability and proven long-term reliability. TT Electronics' portfolio supports demanding power conversion, industrial automation, transportation and energy applications where conventional film resistor technologies cannot withstand sustained electrical or thermal loading, helping engineers achieve dependable performance in high-power and harsh operating environments.

TT Electronics' Wirewound Heritage
 

TT Electronics' Wirewound Heritage

 

TT Electronics' resistor heritage spans three market-leading brands — BI Technologies, IRC, and Welwyn — with a combined track record of over seventy years in resistive component innovation. Wirewound is the technology where that heritage began: Welwyn's earliest products, in 1937, were vitreous enamelled wirewound resistors, developed over the following decades into the well-known green W20 series. Continued process development has since pushed wirewound   construction to higher ohmic values, higher surge energies, and tailored fusing performance.

 

Featured Wirewound Resistor Products

High-Surge (WHS series)

High-Surge (WHS series)

 

Built to absorb short-duration surge and pulse energy well beyond   continuous power rating. The WHS7 is rated 7W continuous, resistance range 1Ω–330Ω, 1% best   tolerance.  

 

Aluminium-Housed / High-Power (WH series)

Aluminium-Housed / High-Power (WH series)

 

Metal-clad, heatsink-mounted construction for TT's   highest wirewound power ratings. The WH50 is rated 50W, resistance range 0.015Ω–120kΩ, 1% best   tolerance.  

 

General-Purpose Cement-Coated (WA80 series).

General-Purpose Cement-Coated (WA80 series).

 

Cement-coated axial construction for general purpose power applications. The WA84 is rated 3W, resistance range 0.01Ω–2.2kΩ, 1% best tolerance.  

 

Fusible (WA80F series)

Fusible (WA80F series)

 

Combines wirewound resistance with predictable, controlled fusing behaviour   for circuit-protection duty. The WA84F is rated 2W, resistance range 0.2Ω–30Ω, 5% best tolerance.  

 

Power Rating
 

Power Rating

 

The maximum continuous power a resistor can dissipate at or below its Rated Ambient Temperature. Above the resistor's Critical Resistance, power rating stops being the limiting factor and Limiting Element Voltage takes over — high-voltage, low-current circuits should be selected against voltage rating, not power rating alone.  

 

Tolerance & TCR
 

Tolerance & TCR

 

Best Tolerance and Best TCR define the highest-precision grades available, and may apply to a restricted ohmic range. The four confirmed series above range from 1% (WHS7, WH50, WA84) to 5% (WA84F) best tolerance — confirm the specific part's datasheet, not a single series-wide figure.  

 

Operating Temperature
 

Operating Temperature

 

Check Rated Ambient Temperature (where full power rating still applies) against Maximum Ambient Temperature (the survival limit). The four confirmed series range from 55°C (WA84F) to 200°C (WHS7, WH50, WA84) maximum ambient — confirm the specific series' figure rather than assuming one site-wide maximum.  

 

Environment
 

Environment

 

For shock, vibration, humidity, altitude, or salt-spray exposure, specify parts tested and qualified against the relevant standard rather than assuming a catalog-standard wirewound part will survive.  

 

Frequently Asked Questions

What is a wirewound resistor used for?

Wirewound resistors are specified for high-power and highsurge applications — motor drives, energy meters, and power conversion circuits — where the wirewound construction's energy-handling capacity matters more than the tight tolerance a film resistor offers.

What's the difference between a wirewound and a film resistor?

A wirewound resistor uses a resistive wire wound around a core, giving it higher power and surge handling for a given size. A film resistor (thick or metal film) uses a thin resistive film instead of wire, favouring tight tolerance and low temperature coefficient of resistance over raw power handling — the right choice depends on whether the application needs power capacity or precision.

What is a high-surge wirewound resistor? 

A high-surge wirewound resistor, such as TT Electronics' WHS series, is built to absorb short-duration surge or pulse energy well beyond its continuous power rating — a common requirement in motor-drive and energy-meter circuits where brief high-energy events occur regularly.