For the voltage regulators to work properly, the regulator wye point must be solidly connected to the transformer X0 or neutral bushing.
For high voltage work, the terms neutral and ground are often used interchangeably. What is actually a neutral connection is commonly called a ground connection.
This is one place where there is a difference and the difference does matter.
The transformer NEUTRAL is separated from the GROUND by a resistor of 450 Ohms.
Again, the regulator wye point must be connected to the transformer neutral, not the ground.
If that is the connection that you have, then check for breaks or corroded or heating connections in the conductor between the regulator wye point and the transformer XO bushing.
Possibly someone has inadvertently used a connection to ground instead of to the XO bushing.
Re-read Mbrooke's post. If the regulator is connected to ground instead of to the XO bushing that is what may happen. If there is an open or bad connection in the conductor from the regulator wye point to the XO bushing, similar things will happen, but possibly worse.
With a solidly grounded system, There is generally a neutral conductor run with the phase conductors. Although this is a neutral it is often grounded at regular intervals and is called a "ground" conductor. Someone used to these systems is ised to connecting the regulator wye point to the "ground" conductor.
When you use a resistor between XO and the ground grid to limit fault currents you may no longer ground the regulator wye point. It must be connected back to the transformer XO bushing.
Bill
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"Why not the best?"
Jimmy Carter
