Structured Manufacturing Data (2026)

Overload Relay

Based on aggregated insights from structured factory profiles within the CNFX directory, the standard Overload Relay used in the Electrical Equipment Manufacturing sector typically supports operational capacities ranging from standard industrial configurations to heavy-duty production requirements.

Technical Definition & Core Assembly

A canonical Overload Relay is characterized by the integration of Bimetallic Strip and Heater Element. In industrial production environments, manufacturers listed on CNFX commonly emphasize Copper construction to support stable, high-cycle operation across diverse manufacturing scenarios.

A protective electrical device that automatically interrupts circuit current when it detects excessive load conditions to prevent motor damage.

View Full Specifications Explore Manufacturing Sources

Product Specifications

Technical details and manufacturing context for Overload Relay

Definition
An essential protective component within the Starter Bucket (Unit) that monitors motor current and disconnects power when overload conditions are detected, safeguarding motors from overheating and damage due to excessive current draw.
Working Principle
Operates by sensing motor current through thermal or magnetic elements. When current exceeds preset thresholds for a specified duration, the relay's contacts open, interrupting power to the motor circuit. Thermal types use bimetallic strips that bend with heat from overcurrent, while magnetic types use electromagnetic coils that trip at specific current levels.
Common Materials
Copper, Plastic, Steel, Bimetallic alloy
Technical Parameters
  • Current rating range typically from 0.1A to 630A, with adjustable trip settings (A) Per Request
Components / BOM
  • Bimetallic Strip Part
    Senses temperature changes from overcurrent and triggers mechanical trip mechanism
    Material: Bimetallic alloy
  • Heater Element Part
    Converts electrical current to heat that affects the bimetallic strip
    Material: Copper alloy
  • Trip Contacts Part
    Electrical contacts that open to interrupt circuit when overload is detected
    Material: Silver alloy
  • Reset Mechanism Part
    Allows manual or automatic resetting of the relay after tripping
    Material: Plastic/Steel

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Overload Relay.

motor overload protection relay bimetallic overload relay for industrial motors electrical equipment overload relay reset mechanism thermal overload relay heater element specifications copper and steel construction overload relay

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Starter Bucket (Unit)
View system integration details
Motor Starters
View system integration details

Industrial Ecosystem & Supply Chain Structure

Complementary Systems
Downstream Applications
Specialized Tooling

Application Fit & Sizing Matrix

Operational Limits
pressure: N/A (electrical device, not pressure-rated)
other spec: Current Range: 0.1-630A typical, Voltage: up to 690V AC, Trip Class: 10, 20, 30 (motor start time tolerance)
temperature: -20°C to +60°C (operating ambient)
Media Compatibility
✓ Induction Motors (3-phase AC) ✓ Conveyor Systems ✓ Pump Applications
Unsuitable: Explosive Atmospheres (unless specifically rated for hazardous locations)
Sizing Data Required
  • Motor Full Load Current (FLC)
  • Motor Service Factor
  • Ambient Temperature

Reliability & Engineering Risk Analysis

Failure Mode & Root Cause
Contact Welding
Cause: Excessive inrush current or frequent short-circuit conditions causing contacts to fuse together, preventing proper tripping.
Calibration Drift
Cause: Thermal aging of bimetallic strips or degradation of electronic components over time, leading to inaccurate trip settings.
Maintenance Indicators
  • Audible buzzing or humming from the relay enclosure indicating loose connections or failing internal components
  • Visible discoloration, scorch marks, or melted plastic on the relay housing suggesting overheating
Engineering Tips
  • Perform regular calibration verification using a primary injection test set to ensure trip settings match motor nameplate data and application requirements
  • Implement infrared thermography inspections during normal operation to detect abnormal heating at connection points and internal components before failure occurs

Compliance & Manufacturing Standards

Reference Standards
IEC 60947-4-1: Low-voltage switchgear and controlgear - Part 4-1: Contactors and motor-starters - Electromechanical contactors and motor-starters UL 508: Standard for Industrial Control Equipment EN 60947-4-1: Low-voltage switchgear and controlgear - Part 4-1: Contactors and motor-starters - Electromechanical contactors and motor-starters (CE marking basis)
Manufacturing Precision
  • Current Setting Accuracy: +/- 5% of rated current
  • Trip Time Tolerance: +/- 10% of specified time at 600% overload
Quality Inspection
  • Dielectric Strength Test: 2500V AC for 1 minute between live parts and ground
  • Calibration Verification Test: Verify trip characteristics across entire current range using calibrated test equipment

Factories Producing Overload Relay

Manufacturer profiles with relevant production capability in China

Add your factory

Manufacturer listings support early research and capability understanding. They are not certification, ranking, or transaction guarantees.

Technical documentation
4/5
Manufacturing capability
4/5
Inspection readiness
5/5
Supplier transparency
3/5

These scores are example evaluation dimensions, not real customer ratings, country-specific buyer feedback, or live inquiry activity.

Supply Chain Compatible Machinery & Devices

Circuit Breaker Arc Chute

Electrical component that extinguishes arcs in circuit breakers

Explore Specs →
Medium Voltage Switchgear Assembly Line

Automated production system for assembling medium voltage electrical switchgear.

Explore Specs →
Motor Terminal Block

Electrical connection interface for motor windings

Explore Specs →
PLC Control System

A digital industrial computer control system that monitors inputs, makes decisions based on a custom program, and controls outputs to automate industrial processes.

Explore Specs →

Frequently Asked Questions

How does an overload relay protect electrical motors?

An overload relay monitors current flow and automatically trips to interrupt the circuit when it detects excessive load conditions, preventing motor overheating and damage.

What materials are used in overload relay construction?

Our overload relays are built with durable materials including copper for conductivity, steel for structural integrity, plastic for insulation, and bimetallic alloy for thermal sensing.

What components make up a typical overload relay BOM?

Key components include a bimetallic strip for temperature sensing, heater element for current measurement, reset mechanism for manual restoration, and trip contacts for circuit interruption.

Can I contact factories directly on CNFX?

CNFX is an open directory, not a transaction platform. Each factory profile provides direct contact information and production details to help you initiate direct inquiries with Chinese suppliers.

Data basis: CNFX manufacturer profiles, technical classification, publicly available product information, and ongoing plausibility checks for Electrical Equipment Manufacturing.

Data Basis

CNFX manufacturer profiles, technical classification, publicly available product information, and ongoing plausibility checks.

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 Overload Relay

Ask for use case, specification boundaries, supplier type, and RFQ preparation information for Overload Relay.

Your business information is used only to process this request.

Thank you! Your message has been sent. We'll respond within 1–3 business days.
Thank you! Your message has been sent. We'll respond within 1–3 business days.

Need to Manufacture Overload Relay?

Compare manufacturer profiles with relevant product and process capability.

Create Manufacturer Profile Contact Us
Previous Product
Output Transformer (if applicable)
Next Product
Pallet Conveyor System