newbie - voltage reading and fuses

[sandwichx]

Lets say you have a 3 phase delta load. Legs A and B are dead but C phase is live. What is voltage measured across each load? Vab, Vbc, and Vac.

I'm guessing that its zero volts for all of them but not sure. You could only see the C voltage to ground with the meter?

When protecting a power transformer do you need a fuse for each leg? On just the primary side?

 

[alehman]

It depends on where the open circuit is with respect to the source transformer and the load.

If you have open fuses at the secondary of the transformer and the load is connected, you will see zero volts line-to-line. If there is no load connected, the voltage will depend on capacitances within the wiring.

If the open circuit is on the primary of the transformer you may see line-to-line voltage between two phases or no voltage, depending on connection of the transformer primary.