A dry power transformer is a transformer in which the iron core and the winding are not immersed in the insulating oil. Cooling methods are divided into natural air cooling (AN) and forced air cooling (AF). Dry-type transformers can operate continuously for a long period of time at rated capacity when naturally air-cooled. When forced air cooling, the transformer output capacity can be increased by 50%. Applicable to intermittent overload operation, or emergency accident overload operation.
1. Short-circuit the “input” and “output” terminals of the transformer and test the insulation resistance of the ground wire with a megger. When measured in a 1000V megohmmeter, the resistance is greater than 2M ohms.
2. The cross-section wiring of the input and output power lines of the transformer should meet the requirements of the current value; it should be configured according to the current density of 2-2.5A/min2.
3. Input and output three-phase power lines should be connected to phase A, phase B and phase C according to the busbar color of the transformer terminal board. The neutral neutral line should be connected to the neutral neutral line of the transformer. Grounding line And the transformer casing (such as the transformer has a chassis should be connected with the box ground wire mark). Check the input and output lines to confirm that they are correct.
4, first no-load power, observe the test input and output voltage meets the requirements. Also observe whether there are abnormal phenomena such as abnormal noise, fire, odor inside the machine. If there is any abnormality, please disconnect the input power immediately.
5. When the no-load test is completed and normal, the load can be connected.
Dry power transformers are an important part of the power system, and their stability and safety have a great impact on the power system. When the transformer is short-circuited, under the action of electric power, the winding is subjected to various forces such as pressing and bending at the same time, and the fault caused by it is sometimes hidden, and it is not easy to inspect and repair. Therefore, the winding condition should be checked after the short-circuit fault. .