What’s the Steps for No-Load Trial Operation of Transformers

1.During the trial operation phase, start by placing the tap changer in the middle position and conduct a no-load trial run. Then, gradually switch to various positions, observing the contacts for proper engagement and ensuring normal operation.

2.If the transformer is connected as a unit with a generator, during the initial startup, gradually increase the voltage to full voltage. For newly installed or overhauled transformers, a full-voltage impulse closing test must be conducted 3 to 5 times to verify the qualification of insulation performance, mechanical strength, electrical protection, fuse devices, and to check for the possibility of misoperation.

3.After the transformer is energized for the first time, the operating time should not be less than 10 minutes. During this period, carefully listen for any abnormal noises inside the transformer. This can be done by using a dry wooden stick or an insulated rod, touching one end to the transformer casing and placing the other end near the ear to detect whether the sound after energization is slight and uniform. If intermittent explosions or sudden loud noises occur, immediately stop the trial run and disconnect the transformer power supply.

4.For transformers with strong wind or forced oil circulation cooling, it is necessary to measure the temperature rise under no-load conditions. The specific procedure is as follows: without activating the cooling device, allow the transformer to run without load for 12 to 24 hours, recording the ambient temperature and the upper oil temperature of the transformer. When the oil temperature rises to 75°C, start 1 to 2 cooling units for heat dissipation, continue measuring and recording the oil temperature until it stabilizes.

LuShan, est. 1975, is a Chinese professional manufacturer specializing in power transformers and reactors for 49 years. Leading products are single-phase transformer, three-phase transformers, DC inductors, AC reactors, filtering reactor, expoxy resin high-voltage transformer and intermediate, high-frequency products. Our transformers and reactors are widely used in 10 application areas: rapid transit, construction machinery, renewable energy, intelligent manufacturing, medical equipment, coal mine explosion prevention , excitation system, vacuum sintering, central air conditioning.

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