INDUSTRY COMPONENT

Fuse or Polyfuse

A fuse or polyfuse is an electrical safety device that protects circuits from overcurrent by interrupting power flow when current exceeds a predetermined threshold.

View Specifications

Component Specifications

Definition
A fuse or polyfuse is a critical component in input protection circuits designed to safeguard electrical and electronic equipment from damage due to overcurrent, short circuits, or fault conditions. Traditional fuses contain a metal wire or strip that melts when excessive current flows, permanently breaking the circuit. Polymer-based positive temperature coefficient (PTC) resettable fuses (polyfuses) use conductive polymer materials that increase resistance dramatically when overheated, temporarily interrupting current until the fault is cleared and the device cools, allowing automatic reset. Both types provide essential protection by limiting current to safe levels, preventing component failure, fire hazards, and equipment damage in industrial applications.
Working Principle
Fuses operate on the thermal principle: when current exceeds the rated value, the fuse element heats up due to its resistance, melting or vaporizing to create an open circuit. Polyfuses use a PTC effect: under normal conditions, the polymer matrix contains conductive particles allowing low resistance; during overcurrent, heat causes the polymer to expand, separating the particles and increasing resistance exponentially, which reduces current to a safe trickle. Once the fault is removed and the device cools, the polymer contracts, restoring conductivity.
Materials
Traditional fuses: Copper, silver, or tin alloys for the fuse element; ceramic, glass, or plastic housing. Polyfuses: Conductive polymer composite (e.g., polyethylene with carbon black), electrodes (nickel or copper), and epoxy coating.
Technical Parameters
ParameterTypical rangeNotes & selection driver
ResistanceMilliohms to ohms
Rated Current0.1A to 100A
Response TimeFast-acting: <1ms, Slow-blow: seconds
Voltage Rating32V to 600V
Breaking CapacityUp to 100kA
Operating Temperature-40°C to 85°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 8820, DIN 72581, IEC 60127, UL 248

Parent Products

This component is used in the following industrial products

Input Protection Circuit

A circuit designed to protect sensitive electronic components from voltage spikes, overcurrent, and reverse polarity at the input stage.

View Product Details

Engineering Analysis

Risks & Mitigation
  • Overheating and fire hazard if incorrectly rated
  • Failure to interrupt due to aging or contamination
  • Nuisance tripping in polyfuses from high ambient temperatures
  • Arc flash in high-voltage applications
FMEA Triads
Trigger: Overcurrent from short circuit or overload
Failure: Fuse fails to open, leading to equipment damage or fire
Mitigation: Use fuses with adequate breaking capacity and regular inspection
Trigger: Material degradation over time
Failure: Increased resistance or premature operation
Mitigation: Select high-quality materials and follow replacement schedules
Trigger: Incorrect installation or rating
Failure: Inadequate protection or nuisance tripping
Mitigation: Follow manufacturer specifications and industry standards

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance
Current rating tolerance typically ±10% to ±20%, depending on type and standard
Test Method
Testing per IEC 60127 for fuses and UL 1434 for polyfuses, including current overload, endurance, and environmental tests

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.

Compare the published product scope and source details, then include your specifications and quantity in an enquiry.

Manufacturers of Fuse or Polyfuse

Manufacturer profiles associated with Fuse or Polyfuse.

Sourcing Fuse or Polyfuse from China?
Tell us your specification and target quantity — we will match it against manufacturer records and come back with the factories that fit.
Request manufacturers We manufacture this

Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.

Share this page

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

Related Components

Terminal Base
A terminal base is an insulating support structure that holds and organizes electrical terminals in motor terminal blocks, providing secure connections and circuit management.
Contact Plate
A conductive plate in motor terminal blocks that establishes electrical contact between conductors.
Marking Strip
A durable marking strip used for terminal identification in motor terminal blocks to ensure proper electrical connections and safety compliance.
Gland Body
A gland body is the main housing component of an aluminum cable gland that provides mechanical protection and environmental sealing for electrical cables entering enclosures.

Frequently Asked Questions

What is the difference between a fuse and a polyfuse?

A fuse is a one-time-use device that must be replaced after operation, while a polyfuse is resettable and can be reused after the fault clears and it cools down.

When should I use a polyfuse instead of a traditional fuse?

Use a polyfuse in applications requiring automatic reset and minimal maintenance, such as in consumer electronics or repetitive fault conditions, but consider traditional fuses for high-breaking capacity or precise protection in critical systems.

How do I select the right fuse rating?

Choose a rated current slightly above the normal operating current of the circuit, considering inrush currents and ambient temperature, and ensure the voltage rating exceeds the system voltage.

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.

Request Manufacturing Insight for Fuse or Polyfuse

Thank you. Your request has been sent. We'll respond within 1–3 business days.
Sorry, we couldn't send your message. Please try again, or email us at [email protected].
Fuse Element / Contacts Gate Control Transistor
Get QuotesChat