Temperature Rise Tests: Adhering to GB/T and IEC Standards
Standards for switchgear temperature rise tests: High-voltage switchgear follows GB/T 3906 (equivalent to IEC 62271-200), while low-voltage switchgear follows GB/T 7251 (equivalent to IEC 61439). The test involves energizing the equipment at rated current to verify that temperature rise limits for various components are not exceeded.
Industry experts note that the core of the “switchgear temperature rise test standard” lies in the specific temperature rise limits—different limits apply to different parts (busbar connections, contacts, component terminals).
These tests are conducted as part of type testing to verify the enclosure’s heat dissipation capability and current-carrying reliability.
Key Points of Temperature Rise Tests
- Test Standards: GB/T 3906/IEC 62271-200 for high-voltage switchgear; GB/T 7251.1/IEC 61439-1 for low-voltage switchgear;
- Test Current: Energize at rated current (or agreed current) until the temperature rise stabilizes (usually taking several hours);
- Measurement Points: Busbar connection points, contacts, component terminals, and internal air temperature;
- Temperature Rise Limits: Busbar connections and contacts (e.g., ≤65K/75K, depending on the standard); component terminals (based on component-specific standards);
internal air (e.g., ≤corresponding K-value); - Test Verdict: The test is passed if the temperature rise at all points remains within the specified limits.
Significance of Temperature Rise Tests
Temperature rise tests verify the heat dissipation and current-carrying capacity of the switchgear enclosure: excessive temperature rise can lead to overheating at connection points, insulation aging, and even fire hazards.
Passing the temperature rise test during type testing indicates that the cabinet operates safely at its rated current.
When purchasing, pay close attention to the specific model associated with the test report;
products with downgraded current-carrying capacity often fail to meet temperature rise standards.
Key Points for Acceptance Verification
First, verify report correspondence: ensure the model and rated current match the temperature rise test report.
Second, validate data: compare actual temperature rise values against limits to confirm compliance.
Third, watch for downgrading: using lower-spec components can result in insufficient current-carrying capacity and a high risk of excessive temperature rise.
Pitfalls to Avoid
First, “missing temperature rise reports”: a type test report lacking temperature rise data is incomplete.
Second, “data falsification”: fabricated temperature rise data can lead to overheating issues during actual operation.
Third, “downgrading/spec-cutting”: passing off lower-specification products as higher-specification ones, leading to temperature rises that exceed limits.
Trends and Reminders
Temperature rise testing is moving toward “digital monitoring”: the digitization of test data and the online monitoring of operating temperatures (e.g., via smart busbars) are becoming the trend.
For purchasers, the recommendation is to “verify the temperature rise report, check limit data, and guard against downgrading.”
Temperature rise testing serves as a health check for current-carrying performance—passing the test ensures stable operation.
