Bimetal Disc: Electrical Rating 10-25A, 250V AC

Component Specifications

Definition

A precision-engineered thermal protection component consisting of two bonded metal strips with different coefficients of thermal expansion. When exposed to temperature changes, the differential expansion causes the disc to snap between convex and concave positions, mechanically opening or closing electrical contacts in compressor protection circuits.

Working Principle

Operates on the differential thermal expansion principle where two dissimilar metals expand at different rates when heated. This causes controlled mechanical deformation (snap-action) at predetermined temperature thresholds, either opening the circuit during overheating or closing it after cooling to safe temperatures.

Materials

Typically composed of manganese-nickel-copper alloy (active layer) bonded to nickel-iron alloy (passive layer) with specific thickness ratios (commonly 0.1-0.3mm each). May include silver-cadmium oxide contacts for electrical switching.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Response Time	<10 seconds at trip temperature
Mechanical Life	>10,000 cycles
Trip Temperature	Typically 100-130°C (adjustable)
Electrical Rating	10-25A, 250V AC
Reset Temperature	Typically 70-90°C below trip point
Operating Temperature Range	-40°C to 150°C

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 1328, DIN 1544, IEC 60947-4-1

Parent Products

This component is used in the following industrial products

Refrigerator Compressor Thermal Overload Protector

The Refrigerator Compressor Thermal Overload Protector is a safety-critical component used in hermetic compressor motors of domestic refrigeration appliances.

View Product Details

Engineering Analysis

Risks & Mitigation

Premature tripping causing compressor shutdown
Failure to trip leading to motor burnout
Contact welding creating permanent short circuit
Calibration drift over time
Mechanical fatigue from vibration

FMEA Triads

Trigger: Material fatigue from thermal cycling
Failure: Loss of snap-action response
Mitigation: Use fatigue-resistant alloys and optimize thickness ratios

Trigger: Electrical arcing during contact separation
Failure: Contact welding and permanent circuit closure
Mitigation: Implement arc suppression circuits and use arc-resistant contact materials

Trigger: Vibration in compressor environment
Failure: Mechanical damage or calibration shift
Mitigation: Add vibration damping mounts and reinforce disc mounting

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Trip temperature tolerance ±3°C, reset temperature tolerance ±5°C

Test Method

ISO 1328 thermal cycling test, IEC 60947 electrical endurance test, vibration testing per MIL-STD-810

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Bimetal Disc

Manufacturer profiles associated with Bimetal Disc.

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Frequently Asked Questions

What causes a bimetal disc to fail in refrigerator compressors?

Common failures include material fatigue from repeated cycling, contact welding due to electrical arcing, calibration drift from prolonged high-temperature exposure, and mechanical damage from vibration or improper installation.

How do you test a bimetal disc's functionality?

Test using controlled heating to verify trip/reset temperatures, measure contact resistance (<50mΩ), check insulation resistance (>100MΩ), and verify snap-action response time. Specialized thermal chambers with precision temperature control are required for accurate testing.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Bimetal Disc