On ring closure
Thread Content
I’m a newcomer; could you, experts, tell me what a closed ring is? How is circulation generated during ring closure? What is a circulating current loop?
In simple terms, a closed-loop system is one in which the units operate in separate sections, with the busbar switch closed to enable parallel operation of the transformers (or of two feed circuits). Generally, this occurs due to differences in load current (resulting from varying loads or transformer capacities). The direction of the circulation is toward the low-load side, and then toward the power source side.
Circuital connection occurs when two broken busbars operate in parallel, with circulating currents arising mainly due to a mismatch in phase; high voltage can be used to synchronize the two sections before parallel operation. The simplest way to connect two low-voltage transformers in parallel is to first connect the high-voltage transformers in parallel, and then arrange the low-voltage transformers accordingly. The conditions for connecting the two transformers in parallel include identical winding connections, short-circuit impedance, transformation ratio, a capacity ratio not exceeding 1/3, and the same phase sequence.