1. Oil-immersed structure

1. When U>=1000KV, cascade structure is generally adopted and auto-coupling connection is used.

2. Capacity utilization rate of n-level cascade devices = 2/(n 1); the more stages, the lower the capacity utilization rate (generally no more than three units)

3. The ratio of the capacities of three power frequency test transformers: 3:2:1

1. Series resonance: The output voltage of the test transformer cannot meet the test requirements (equivalent to reducing the voltage of the required test transformer)

2. Parallel resonance: The capacity of the test transformer is insufficient, but the output voltage meets the requirements (equivalent to reducing the capacity of the required test transformer)

1. Longitudinal insulation of fully insulated transformer

2. Main insulation and longitudinal insulation of graded insulation transformers

1. Technical Parameters

2. Basic technical parameters of half-wave rectifier circuit

1. Output voltage = 2nU (n is the number of stages)

2. Slow boost speed

1. Insulation performance under power frequency working voltage, temporary overvoltage, and operating overvoltage

2. Insulation performance under lightning overvoltage

1. Insulation performance under operating overvoltage

2. Insulation performance under lightning overvoltage

1. The maximum voltage does not exceed 200-300kV

2. Wave front resistance Rf<< wave tail resistance Rt

3. Main capacitor C0>>Load capacitor Cf

1. Subject the tested product to three positive polarity and three negative polarity lightning impulse withstand voltage tests (1.2/50us full wave)

2. For equipment with windings (transformers, reactors), a lightning impulse chop wave (1.2/2-5us full wave) withstand voltage test is also required.