Overview
Overview
Cement resistors are power-type resistors made by winding high-stability alloy wire, encapsulating it in a heat-resistant ceramic shell, and filling the outer layer with flame-retardant insulating cement. The resulting structure is robust, with excellent heat resistance, flame retardancy and mechanical strength — providing stable long-term operation under high loads and harsh conditions. They deliver good thermal performance and a relatively low temperature coefficient, making them well-suited for power dissipation, current limiting and voltage division in critical circuit nodes.
Key Features
High Power Handling
- Withstands large transient surges and continuous loads
- Suitable for high-power applications
Excellent High-Temperature Performance
- Ceramic shell + cement encapsulation
- High flame-retardant rating, safe and reliable
Robust & Durable Construction
- Strong vibration resistance
- Suitable for industrial equipment and harsh conditions
High Stability
- Low resistance drift
- Stable performance over long-term operation
Good Thermal Performance
- Shell promotes rapid heat conduction
- Reduces heat accumulation
Wide Spec Variety
- Custom power, resistance and dimension options
- Meets diverse design requirements
Models
Models
Applications
Typical Applications
SMPS / UPS
Inverter / Servo
New-Energy Equipment
Home Appliances
LED Drivers / Adapters
Test & Load Banks
Frequently asked questions
Are cement resistors flame-retardant and safe for switching power supplies?
Yes — our cement housing is rated UL94 V-0 flame-retardant, and the inorganic refractory cement does not propagate flame even on internal element burnout. This makes them the preferred choice for power supplies, lighting ballasts and motor-starting circuits where one-fault safety is required. Operating temperature −40°C to +275°C (case).
What's the difference between cement, wirewound and metal-film resistors?
Construction differs: cement uses a wirewound element inside a flame-retardant cement block (1–100 W, surge-tolerant); pure wirewound is the same element with vitreous-enamel or silicone coating (more compact, less robust); metal-film is sputtered film on ceramic (smaller, lower power 1/8–3 W, low noise). Choose cement for safety + power, wirewound for power density, metal-film for precision in low-power signal paths.
What lead/termination options are available — axial, radial or PCB?
All three. Axial lead (SQP-style) for through-hole and chassis mounting, 1–100 W. Radial lead (SQM-style) for vertical PCB mounting, 1–25 W. Tab terminals (M3/M4 stud or quick-connect) for high-current applications above 25 W. Lead wire is tinned copper, 0.6–1.2 mm diameter; longer leads or pre-formed shapes available on order.
How well do cement resistors handle pulse and surge currents?
Excellent — the wirewound element with cement encapsulation gives high thermal mass and prevents arcing. Typical short-pulse rating: 10× rated power for 1 second, 50× for 100 ms. Single-pulse capacitor discharge: 5W cement absorbs around 5 J, 25W absorbs around 30 J. Ideal for inrush current limiting and snubber duty in power supplies and motor drives.
Are cement resistors moisture resistant for humid or coastal environments?
Standard cement is moderately hygroscopic — fine in normal indoor environments. For high humidity (>85% RH continuous) or salt-spray exposure we offer epoxy-impregnated and silicone-coated variants that pass 96-hour humidity test (IEC 60068-2-78) and 48-hour salt-spray (IEC 60068-2-11) with no measurable resistance change. Specify 'HR' suffix for the humidity-resistant version when ordering.
Sample Request
Sample Request
Standard samples are provided free of charge in reasonable quantities (shipped within 2–3 business days). Custom samples are delivered within 2–4 weeks. Please use the form on the right to tell us:
- Company and contact details
- Target part number or key specs (power / resistance / package)
- Application scenario and estimated annual volume
- Shipping address and expected delivery date
📧 You can also email us directly at info@resistor-factory.com / 13650089870
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