Under what circumstances should an arc suppression coil be taken out of service when it is installed?

When installing an arc suppression coil, it is important to identify the conditions under which the coil should be taken out of service. The arc suppression coil should be disconnected under the following circumstances:

• When a transformer is being de-energized, the neutral-point disconnector must be opened first before performing any switching operations on the transformer. The energizing sequence is the reverse: the neutral-point disconnector should be closed only after the transformer is energized. It is prohibited to energize the transformer with the neutral-point disconnector closed, or to open the neutral-point disconnector after the transformer has already been de-energized.

• The arc suppression coil should be taken out of service when a substation is being synchronized (paralleled) with the grid.

• The arc suppression coil should be taken out of service during single-source (single-supply) operation.

• When the system operating mode changes such that the network is split into two separate sections, the arc suppression coil should be disconnected.

• The arc suppression coil should also be taken out of service whenever other significant changes occur in the grid operating configuration.