Please help me explain what is the two phases in the relay,
Is a relay or a contactor. There is AC, DC control.
Two-phase three relays are over-current protection of the wiring, with A, C-phase current transformer to achieve A, B, C three-phase over-current relay protection.
This is an over-current protection of the wiring, generally in large-capacity transformers, or total step-down transformer generally use Y / Δ-11 wiring. If the secondary side of the two-phase short-circuit (set a, b two-phase short circuit), flow through the transformer primary side A, C two-phase short-circuit current equal size, the same direction; flow side of the current phase B and A, C Phase current compared to the opposite direction, the size is A, C phase current twice. As the primary side of the transformer A, C current equal size, the same direction, so installed in the transformer side of the over-current protection and current quick-break protection, if only in the A, C phase current transformer installed, can not use differential form, The current flowing into the relay when the two phases are short is zero. In order to improve the protection of the sensitivity, it is best to use the whole star wiring, or two current transformer three current relay wiring
