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Brief Introduction of Temperature Rise Test for Low Voltage

At the end of the experiment, the temperature increment should not exceed the rule value in the specification. Components should operate well at the internal temperature of a complete set of equipment and within its regular voltage limit.
 
GB7251.1-2013 Before measuring temperature rise, complete sets of equipment should be put in place as usual and all cladding plates should be in place. Apply additional voltage to the coils of relays, touchers, trippers, etc. The complete set of equipment for temperature rise should be representative. If the system under test contains several plans, the most rigorous set of equipment system should be selected for experiment. Measurement of temperature rise
 
When measuring temperature rise point with thermocouple, the influence of air activity and thermal radiation on thermocouple should be avoided. The experimental time is enough to make the temperature rise rise to a stable value (generally not exceeding an hour). In practice, when the temperature rise does not exceed, the temperature rise is considered stable. If the component promises, it can increase the current at the beginning of the experiment and then decrease to the regular experimental current value, so as to shorten the experimental time.
 
5. Measurement of Environmental Stability
 
The ambient temperature should be measured during the last period of the experimental period. At least two thermocouples or thermometers should be uniformly arranged around the whole set of equipment. The height of the thermocouple is about one-half of that of the whole set of equipment. The influence of air activity and thermal radiation on the thermometer or thermocouple should be avoided.
 
7. Temperature rise experimental circuit
 
When 400A < span font-size: 14px; "=">", single-phase method can be considered. Only when the effect of magnetic field is small enough to be neglected can multiphase complete sets of equipment promise to use single-phase communication electricity. This is because the experiment with single-phase power supply will produce proximity effect when two adjacent conductors communicate with each other, which makes the current distribution in the conductor uneven, reduces the effective area of the conductor in practice, and increases the practical resistance of the conductor. Because the phase of three-phase and single-phase is different, the influence of proximity effect among conductors is also different, so the temperature rise in temperature rise experiment is also different.