Ground switches are used for added protection for the operator of the bank. Basically there are three different scenarios with the use of the ground switch. The most used is to discharge the capacitors directly to ground removing any trap charges in the capacitors.

I. Medium voltage capacitors will hold a charge from 3 to 5 minutes after they are de- energized. They have internal discharge resistors, which by IEEE standard are to reduce this charge to 50 volts within five minutes.

1. Three pole ground switches can be used on grounded Wye and delta connected banks.
2. Four pole ground switches should be used on floating Wye connected banks.
3. The ideal location for the ground switch would be on the load side of the capacitor switch and line side of the capacitor and its fuse. This will discharge the capacitors directly to ground and the dumping of the energy would not go through the switch.
4. The capacitor rated switch will have to opened first and then the visible disconnecting device will have to be opened before the ground switch is closed.

II. Some applications the customer may want to assure the incoming line is grounded before entrance to the bank can be accomplished for any maintenance or repair is started.

1. This switch can be a group operated three-pole switch regardless of the bank connection.
2. This switch should be on the load side of a visible disconnecting means to the bank.
3. Here again the capacitor rated switch should be opened first then the disconnecting device needs to be open before the ground switch can be closed.

III. If a combination is preferred, that is the incoming line is grounded and the capacitors are shorted a main ground switch could be used.

1. The switch should be a four-pole ground switch on floating wye banks.
2. The capacitor rated switch would have to be opened before the disconnect switch is opened. However, here the capacitor rated switch needs to be reclosed. This can be done before or after the ground switch is closed. This will allow the capacitors to discharge through the capacitor rated switch.

On multiple staged capacitor banks a separated ground switch can be used as described in section I. This will allow each individual step to be grounded discharging the capacitors in that step. If one step is out due to repair or, maintenance, this step can remain grounded while the other steps remain operational.

No matter which method is used it is recommended that the grounding switch and any other switching device used in the required procedure to maintain the bank be interlocked with each device. This is to prevent inadvertent closing of the ground switch with a load or, voltage on the ground switch.