Transformer three-phase dual power supply automatic switching

This article describes in detail the operation steps of the dual power supply automatic switching circuit, the connection between the contactor and the load, etc., as well as manual automatic conversion, phase loss protection, etc.

When A, 1 substation has electricity, KA is energized and closed, its normally open contact is closed, contactor km1 is energized, and 1 substation is switched on, the load uses 1 substation, and the normally closed contact of KA is disconnected , Km2 cannot receive electricity.

B. When the 1st transformer loses power, ka loses power and returns, its normally open contact disconnects km1. The normally closed contact of ka closes and the contactor km2 is energized, and the 1st transformer enters the load through km2. The load uses 2 changes.

C. This circuit adopts the double interlocking structure of the normally open and normally closed relay ka and the contactor km1 km2 normally open and normally closed, which is safe and reliable.

D. This circuit design is mainly based on the power consumption of 1 variable. If there is a manual selection knob, manual and automatic conversion can be realized. , Four first three-position knob switches, left-handed to disconnect the relay ka, right-handed to disconnect the km2 coil, both sides of the middle position are paths.

E, if the relay ka is connected to the A and B phases, the phase loss protection of 1 variable can also be realized.

F. If a relay ka2 is added to the 2nd transformer and the coil is connected to the A and B wires of the 2nd transformer, the power is interlocked with ka1, and the power of km2 is controlled by ka2 to realize the phase loss protection of the 2nd transformer.