In the case of a commercial building served by 3 phase - closed delta
240/120 Vservice, what is the best way to detect a ground fault on a
three phase motor circuit on phase C were it to come into contact with
the ground?
Whereas the service transformer on phase AB has the only centered tapped (neutral) windings 120V phase-to-neutral and 240V phase-to-phase and phase C (not connected to the phase AB transformer) is the wild phase.
It seems to me that (without additional protective equipment), if phase C accidently touches the ground there would be a voltage imbalance, but the overcurrent protection would not necessarily trip off.
Am I wrong by assuming this?
Also, what, in general, are the pros and cons of a 120/240V 3 phase closed delta connection?
Is this a good choice for a small commercial building with a 3 story hydraulic elevator and mostly 120V. appliance and lighting loads?
Beachcomber
Whereas the service transformer on phase AB has the only centered tapped (neutral) windings 120V phase-to-neutral and 240V phase-to-phase and phase C (not connected to the phase AB transformer) is the wild phase.
It seems to me that (without additional protective equipment), if phase C accidently touches the ground there would be a voltage imbalance, but the overcurrent protection would not necessarily trip off.
Am I wrong by assuming this?
Also, what, in general, are the pros and cons of a 120/240V 3 phase closed delta connection?
Is this a good choice for a small commercial building with a 3 story hydraulic elevator and mostly 120V. appliance and lighting loads?
Beachcomber