Purpose of Megger Guard Terminal

[justin6354]

What is the purpose of the Guard terminal on a Megohmeter?

[SecondGen]

When testing at higher voltages, such as with cable or transformers, the guard terminal can be used to divert surface leakage from the measuring circuit. For example, if you were performing a Primary to Ground test on a transformer you would guard the secondary windings. Not all insulation testers are equipped with a guard terminal.

[joaogemal]

If you understood that, which is a excellent explanation, you can transport to the Power Factor testing. The guard, for example, GST - Guard Red, is the same idea, divert from the measurement whatever is connected to the red.

[wightywest]

So does the guard allow voltages to pass through or does it immediately go to ground?

[Relay1]

So does the guard allow voltages to pass through or does it immediately go to ground?

A simple way to look at it is, you have a closed circuit with the current returning to it's source at the test equipment. Depending on how you hooked up the leads from the set, all or sections of the device current (Leakage) will be measured. The ground lead is just another path back to the test set whether you measure it or not.