Main Components and Functions of Power Transformers

①、The primary and secondary coils of an ordinary transformer are concentrically wound on the same iron core leg, with the low-voltage winding inside and the high-voltage winding outside. (For welding machine transformers, the primary and secondary coils are mounted on two separate iron core legs.) When the transformer operates under load and the secondary current increases, the transformer must maintain the main magnetic flux in the iron core unchanged, so the primary current must also increase correspondingly to balance the secondary current. The on-site tester for voltage transformers solves the problems of high work intensity and cumbersome operation in on-site calibration of voltage transformers, and this product is reliable in performance and powerful in function.

The secondary active power of a transformer is generally equal to the transformer's rated capacity (KVA) × 0.8 (transformer power factor) = KW.

②、The main components of a power transformer include:

A. Moisture absorber (silica gel cylinder): It contains silica gel. The insulating oil in the oil conservator (oil pillow) is connected to the atmosphere through the moisture absorber. The desiccant absorbs moisture and impurities from the air to maintain good insulation performance of the transformer's internal windings. If the silica gel changes color or deteriorates, it may cause blockage.

B. Oil level gauge: It reflects the oil level status of the transformer, generally around +20°C. If it is too high, oil needs to be drained; if too low, oil needs to be added. In winter, when the temperature is low and the load is light, the oil level changes little or slightly decreases; in summer, when the load is heavy, the oil temperature rises and the oil level also slightly rises; both are normal.

C. Oil conservator: It regulates the oil volume in the tank and prevents excessive oxidation of the transformer oil. There is an oil filling hole at the top.

D. Explosion-proof pipe: It prevents the danger of explosion caused by sudden pressure increase in the oil tank due to accidents.

E. Signal thermometer: It monitors the operating temperature of the transformer and sends signals. It indicates the top oil temperature of the transformer. The coil temperature is 10°C higher than the top oil temperature. According to national standards, the maximum working temperature of the transformer winding is 105°C (i.e., when the ambient temperature is 40°C), and the top oil temperature should not exceed 95°C. It is usually advisable to set the monitoring temperature (top oil temperature) at 85°C or below.

F. Tap changer: It changes the voltage ratio by changing the taps of the high-voltage winding, increasing or decreasing the number of winding turns.

∵: U1/U2 = W1/W2, U1W2 = U2W1,

��: U2 = U1W2/W1.

Generally, transformers are no-load voltage regulating, requiring power outage for adjustment: usually divided into three gears I, II, III with +5%, 0%, -5% (primary voltages of 10.5KV, 10KV, 0.95KV; secondary voltages of 380V, 400V, 420V). They are usually set to gear II at the factory.