What causes circulating current?

Circulating currents are a result of an asymmetry in the motor and the voltage it creates between the stator and rotor iron, but not related to the motor drive or method used to drive the motor. Specifically, the asymmetry in a motor comes from imbalanced windings, the differences in the iron core, and air gaps.

What is circulating current in parallel generators?

Circulating Currents Travel a Certain Particular Path In general, circulating currents leave the line leads of the first generator, move through the parallel bus of the second generator and come back into the second generator.

What is meant by circulating currents?

When two substations are conected through a switch, there may be a voltage difference between the sites. When the switch is closed, creating a parallel, it is said that current flows between the sub stations, known as ‘circulating current’.

What is circulating current and why it should be avoided in parallel operation?

Circulating currents that diminish load capability and increased losses. The bus ratings could be too high. Paralleling transformers reduce the transformer impedance significantly, i.e. the parallel transformers may have very low impedance, which creates the high short circuit currents.

Why is circulating current bad?

Circulating current are those which keep circulating between transformers and does not contribute to load current. This causes unnecessary ohmic losses and decreased efficiency. Also transformer heats up due to increased current flow.

What’s circulating current?

Generally circulating current refers to current flow in a transformer bank that is attempting to correct an imbalance problem. Circulating currents are very common in Delta connected transformer windings and in some cases a transformer bank may be placed into service with no specific load attached.

What is neutral circulating current?

The circulating current is driven by the voltage induced on the neutral from the phase conductor. Circulating currents are worse with larger conductors and with wider separation between cables. Two configurations are given: (1) cables in separate ducts and (2) all three cables in the same duct.

How is circulating current calculated?

Conceptually, it really is as simple as Ohm’s Law: I = V/R. Of course that is an over simplification, but it is the same concept applied to three phase AC systems. Now let’s take a deeper dive into how to calculate circulating current.