Users need to master the wiring method when using dry type transformers. If there is a problem in the wiring, it will easily lead to malfunctions. So what is the wiring method of the three phase dry-type transformer? Let us introduce it.
Connection Wiring method of dry type transformer:
1. Short-circuit the "input" and "output" terminals of the transformer to test the insulation resistance with the ground wire with a megohmmeter. When measuring with a 1000V megohmmeter, the resistance is greater than 2M ohms.
2. The cross-section wiring of the transformer input and output power lines should be in accordance with the requirements of the current value; it is appropriate to configure the current density of 2-2.5A/min2.
3. The input and output three-phase power lines should be connected to phase A, phase B, and phase C respectively according to the color of the busbar of the transformer terminal block, yellow, green, and red. The neutral line should be connected to the neutral neutral line of the transformer, the grounding line, and the transformer The shell and the transformer point are connected. The ground and neutral wires we usually talk about are drawn from the neutral point of the transformer. (For example, the transformer box should be connected to the corresponding ground mark of the box body). Check the input and output lines to confirm that they are correct.
4. First power on at no-load and observe and test that the input and output voltages meet the requirements. At the same time, observe whether the machine has abnormal noises, sparks, odors and other abnormal phenomena. If there are abnormalities, please disconnect the input power.
5. After the no-load test is completed and normal, the load can be connected.
The dry-type cast resin transformer has a discharge sound. If a partial discharge occurs on the transformer or the surface, there will be a "crack" discharge sound in the sound. When this happens, if you can see blue corona or sparks near the transformer bushing at night or in rainy weather, it means that the porcelain is very dirty or the equipment clamps are in contact; if the transformer is discharged, it is not Electrostatic discharge of grounded parts, or contact discharge of tap changer, at this time, the transformer should be further tested or disabled.
The dry-type power transformer has a sound of boiling water. If the sound of the transformer is mixed with the sound of water boiling, the temperature changes, and the oil level rises, it should be judged that the transformer winding has a short-circuit fault, or the tap switch has caused serious overheating due to contact. At this time, the transformer should be stopped for inspection.
The epoxy cast resin type transformer has a popping sound. If there is uneven popping sound in the sound of the transformer, it is the insulation breakdown of the transformer or the surface. At this time, the transformer should be stopped for inspection.
The above sound problem is a detail that cannot be ignored. Everyone should take good care of it. Otherwise, it will not work well. Not only does the dry type transformer work badly, it may also shorten the service life!
Varelen Electric Co., Ltd