Distribution Transformer Overvoltage
Distribution Transformer Overvoltage
(OP)
What is the likely overvoltage that would result during a primary neutral break to an overhead single-phase distribution transformer rated 2.4 kV Line-to-Neutral that provides 120/240V three-wire secondary service?
A secondary voltage of 156 V was measured on one of the secondary legs to ground.
A secondary voltage of 156 V was measured on one of the secondary legs to ground.






RE: Distribution Transformer Overvoltage
The impedance of the ground connection will be important. It sounds as if your local ground is of so high an impedance to be relatively ineffective.
Bill
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"Why not the best?"
Jimmy Carter
RE: Distribution Transformer Overvoltage
Secondary voltage of 156 V was recorded at customer service panel. Upon inspection, it was noticed that the primary neutral connection to the transformer serving this customer was broken and no longer connected to the transformer. Transformer at this point was undergrounded (i.e. only capacitively connected to ground). Primary neutral was repaired and customer voltage returned to normal.
I would not expect such a large voltage fluctuation on the secondary side of the service transformer due only to the broken primary neutral connection.
RE: Distribution Transformer Overvoltage