Wirewound resistor guide: ceramic core, vitreous enamel, aluminum-housed. ADD stocks Vishay, Ohmite, KOA Speer. Buy wirewound resistors online from HK distributor.
Wirewound Resistors — High-Stability Power & Precision
Wirewound resistors are constructed by winding a resistive alloy wire — typically nickel-chromium (nichrome), copper-nickel (constantan), or manganese-copper (manganin) — around an insulating ceramic or steatite core. This construction delivers a combination of attributes that film and composition resistors cannot easily match: high power dissipation, outstanding pulse and surge energy handling, low temperature coefficient of resistance (TCR), and excellent long-term stability. At ADD Components we source wirewound power and precision resistors across ceramic core, vitreous enamel coated, and aluminum-housed chassis-mount formats, supporting designers and procurement teams who buy resistors online for industrial, automotive, and instrumentation applications. Below we summarise the principal product types, the parameters that matter most during selection, and a representative cross-section of parts from Vishay, Ohmite, and KOA Speer that we stock.
Product Types
Ceramic Core Wirewound Resistors
Ceramic core wirewound resistors form the foundation of the category. A high-purity ceramic or steatite rod provides the winding former, offering high thermal conductivity, excellent dielectric strength, and dimensional stability across temperature. The resistance alloy is wound onto the core and protected by a silicone, cement, or lacquer coating. This format delivers stable resistance over a wide operating range and tolerates high surge currents and momentary overloads without degradation. Vishay's RS series and KOA's BWR cement-coated power resistors are representative ceramic core wirewound parts, widely used in power supplies, motor drives, snubber networks, and inrush current limiting.
Vitreous Enamel Coated Wirewound Resistors
Vitreous enamel coated wirewound resistors are fired with a fused glass coating that bonds chemically to the ceramic core and resistance element. The enamel layer is highly resistant to moisture, chemicals, abrasion, and extreme temperature, making these parts ideal for harsh industrial environments, dynamic braking, motor starting, and load-bank duty. The glass coating also improves thermal conductivity and mechanical robustness. Ohmite's 20J series is the classic vitreous enamel wirewound resistor, offered in axial-leaded form with power ratings up to 10 W and beyond, and remains a staple for equipment builders seeking a dependable resistor supplier.
Aluminum-Housed (Chassis-Mount) Wirewound Resistors
Aluminum-housed wirewound resistors encase the wound element in a finned or flat extruded aluminum shell, filled with an inorganic thermally conductive compound. The housing is bolted directly to a heatsink or chassis, allowing continuous dissipation of 25 W, 50 W, 100 W or more in a compact footprint. Because heat is removed through the case rather than the leads, these parts suit high-power applications such as motor control, servo drives, power conversion, and load testing. Vishay's RH series — including the RH25 and RH50 — is a widely specified aluminum-housed range that ADD Components supplies for both prototype and production quantities.
Precision Wirewound Resistors
Precision wirewound resistors deliver the tightest tolerance and lowest temperature coefficient of any wirewound format. Using selected resistance alloys and stress-relieved winding, they achieve tolerances from ±1% down to ±0.01% and TCR values as low as ±20 ppm/°C, with exceptional load-life stability. Non-inductive Ayrton-Perry windings are available where low inductance is critical in high-frequency or switching circuits. These characteristics make precision wirewound parts indispensable in analogue instrumentation, metrology, current-sensing bridges, and feedback networks. Vishay's RS precision wirewound series is the most commonly specified family; KOA's MOS metal oxide film range offers a flameproof precision alternative where wirewound construction is not required.
Key Selection Parameters
Resistance Value & Tolerance: Wirewound parts span milliohms to megohms. Tolerances of ±5% suit power and braking duty, while ±1% and tighter grades are required for precision measurement circuits.
Power Rating (W): The maximum continuous dissipation at rated ambient temperature. Derate linearly above the rated temperature and verify the mounting surface for chassis-mount types.
Temperature Coefficient (TCR): Measured in ppm/°C. Standard power wirewounds run ±50 to ±400 ppm/°C; precision grades reach ±20 ppm/°C or better.
Coating & Construction: Silicone or cement coatings for general duty, vitreous enamel for harsh or high-temperature environments, and aluminum housings for heatsink-mounted high-power designs.
Surge & Overload Capability: Wirewound resistors absorb substantial pulse energy. Verify the short-time overload and pulse ratings when specifying for inrush, braking, or snubber duty.
Inductance: Standard helical windings are inductive. Choose Ayrton-Perry non-inductive versions for high-frequency, RF, or fast-switching applications.
Mounting: Axial through-hole leads for PCB mounting versus chassis or heatsink mounting for aluminum-housed parts that rely on case contact for cooling.
Representative Resistors We Source
| Part Number | Brand | Type | Key Spec |
|---|---|---|---|
| RS01A100R0FE12 | Vishay (Dale) | Precision Wirewound Axial | 100 Ω, ±1%, 1 W, low TCR |
| RS05B10R0FE12 | Vishay (Dale) | Precision Wirewound Axial | 10 Ω, ±1%, 5 W |
| RS010B100R0FE12 | Vishay (Dale) | Precision Wirewound Axial | 100 Ω, ±1%, 10 W |
| RH25 25R0 | Vishay (Dale) | Aluminum-Housed Chassis Mount | 25 Ω, ±5%, 25 W |
| RH50 10R0 | Vishay (Dale) | Aluminum-Housed Chassis Mount | 10 Ω, ±5%, 50 W |
| 20J100E | Ohmite | Vitreous Enamel Wirewound | 100 Ω, ±5%, 10 W axial |
| 20J1R0E | Ohmite | Vitreous Enamel Wirewound | 1 Ω, ±5%, 10 W axial |
| TGH100 | Ohmite | Thick Film TO-220 Power | 100 Ω, ±5%, 100 W (heatsink), non-inductive |
| BWR5 100R J | KOA Speer | Cement Wirewound Power | 100 Ω, ±5%, 5 W |
| MOS3 100R J | KOA Speer | Metal Oxide Film Power | 100 Ω, ±5%, 3 W, flameproof |
Send Us Your Resistor Requirements
ADD Components is a Hong Kong-based electronic components distributor supplying wirewound power and precision resistors to OEMs, EMS providers, and engineering teams worldwide. We hold and source Vishay RS and RH series, Ohmite 20J and TGH series, and KOA BWR and MOS series, with factory-original traceability and anti-counterfeit inspection on every shipment. Whether you need a single value for prototyping or a scheduled production program, our team provides same-day quotations and flexible volumes for resistor wholesale and scheduled-delivery orders.
Send your part numbers or bill of materials to Info@addcomponents.hk and we will confirm pricing, availability, and lead times — and recommend equivalent or drop-in alternative parts where lifecycle or supply constraints apply.
Email: Info@addcomponents.hk | Tel: +852 5334 3091 | WhatsApp: +852 5334 3091
Last updated on August 18, 2026