Rectifier Transformer

Rectifier transformer

1. Product description

Usually the rectifier is connected to the power grid through a rectifier transformer, so the rectifier transformer is one of the important electrical equipment in the rectification process, and its main uses are:

● Reduce the high voltage of AC to a value equivalent to the output DC voltage.

● Change the three-phase AC system into a polyphase AC system, and increase the number of phases on the secondary side of the rectifier transformer, which can improve the waveform of the DC voltage after rectification.

Therefore, the number of phases on the secondary side of the rectifier transformer is generally not less than three phases, and it is often six or twelve phases. The difference between the rectifier transformer and the power transformer is that the load characteristics of the secondary side are different, the load of the power transformer is generally a constant impedance, the output current is sine-wave type, and the rectifier transformer because of the role of the rectifier, each anode is only conductive in each part of the same waveform, so the output voltage of the secondary side of the rectifier transformer is different. Secondly, the secondary current waveform in the coil of the rectifier transformer is not a sine wave, but a pulsating waveform, which determines that the secondary capacity of the rectifier transformer is greater than the primary capacity in the six-phase and twelve-equal rectifier lines.

2. Performance characteristics

In order to obtain a certain rectified DC voltage, there must be a corresponding AC rectified power supply. The AC voltage of the power network often cannot meet this need. Transformers are usually used to convert the AC voltage of the power network into the required AC rectified power supply. This transformer used to obtain rectified power supply is called a rectifier transformer, and its working principle is the same as that of a power transformer, but it has the following characteristics:

Although the rectifier transformer uses a sine wave to supply power from the primary side, since each phase of the secondary coil can only have current in part of the cycle, the current of the primary coil is non-sinusoidal according to the waveform, which determines that the secondary capacity of the rectifier transformer is greater than the primary capacity. (six-phase and twelve-phase) rectifier transformers have large secondary currents and low voltages, so their coils and leads require higher mechanical strength. In addition to single phase and three phase, rectifier transformers are often made into six phases and twelve phases. In this way, DC voltage with small pulsation can be obtained, and silicon rectifier elements can be fully utilized, or it is conducive to the acquisition of high current and low voltage.

The electrical performance of the rectifier transformer impedance voltage drop, short circuit loss, no-load loss and other parameters, there is no unified standard at present, but according to experience, the parameters of the same capacity power transformer or slightly larger.

The volume and weight of the rectifier transformer are generally larger than that of the power transformer of the same capacity.