Overview
IEC 63522-37:2025 is an international standard developed by the International Electrotechnical Commission (IEC) that provides a standardized test method to measure the terminal temperature rise of electrical relays under rated load conditions. This standard part of the IEC 63522 series focuses specifically on assessing the thermal performance of various relay terminals, including solder terminals, flat quick-connect terminations, screw and screwless type terminals, alternative termination types, and sockets.
This standard aids manufacturers and testers in ensuring electrical relays maintain safe operating temperatures during continuous use, facilitating reliable operation under expected transportation, storage, and operational environments.
Key Topics
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Scope and Purpose:
IEC 63522-37:2025 is applicable to all kinds of electrical relays, such as electromechanical relays, reed relays, solid-state relays, and time relays. The standard's primary objective is to evaluate the temperature rise at terminals when relays are energized under maximum rated resistive load.
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Test Procedures:
The standard defines two test procedures:
- Group Mounting (Test Procedure A): Testing three relays mounted side-by-side to simulate real-life mechanical arrangements.
- Single Mounting (Test Procedure B): Testing one relay individually to measure its terminal temperature rise.
Terminals must be secured with specific torque levels per IEC 60998-1 or IEC 60999-1 guidelines, and screwless terminals require proper conductor insertion.
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Environmental Conditions:
Tests occur in a heat chamber without forced convection to prevent artificial cooling. Ambient temperature is maintained at room temperature or the upper limit of the operating range, ensuring consistency and representative results. Testing also accounts for maximum altitude or corresponding atmospheric pressure conditions.
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Measurement Techniques:
Temperature at the terminals is measured using fine wire thermocouples (typically 28 or 30 AWG) positioned close to the relay body to avoid measurement errors. Alternate measurement methods are permitted if they demonstrate equivalent accuracy.
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Evaluation and Reporting:
The standard requires process monitoring, visual inspection, and final checks to validate test integrity. Comprehensive test reports detail the methodology and findings, promoting transparency and reproducibility.
Applications
IEC 63522-37:2025 is essential for:
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Relay Manufacturers:
To validate that relay terminals comply with thermal performance specifications under operational loads, ensuring product reliability and safety.
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Quality Assurance and Testing Laboratories:
To systematically evaluate terminal temperature rise for a variety of relay types, supporting certification and quality control processes.
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Electrical Designers and Engineers:
To select appropriate relays that meet temperature rise requirements, optimizing performance in systems where temperature sensitivity is critical.
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Safety Compliance:
Supporting adherence to international safety standards by confirming that terminal temperatures remain within acceptable limits during rated operation.
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Product Development:
Enabling the design of new relay terminals and mounting solutions with verified thermal characteristics.
Related Standards
- IEC 63522-0: General and guidance for electrical relay tests and measurements.
- IEC 61810-1: Electromechanical elementary relays – general and safety requirements.
- IEC 60584-1: Thermocouples – EMF specifications and tolerances.
- IEC 60998-1: Connecting devices for low-voltage circuits – general requirements.
- IEC 60999-1: Connecting devices – safety requirements for screw and screwless clamping units.
These related standards complement IEC 63522-37 by providing foundational specifications and requirements relevant to relay testing, thermocouples, and terminal connections.
Keywords: IEC 63522-37:2025, electrical relays, terminal temperature rise, rated load, relay testing, thermocouples, relay terminals, screw terminals, quick-connect terminations, IEC standards, electromechanical relays, solid-state relays, relay temperature measurement, electrical relay safety, relay test procedures, international relay standards.