Voltage Loss on Delta Service
Voltage Loss on Delta Service
(OP)
We have a monitoring device installed at a 3-ph, 480V 3-wire delta service to monitor our disturbances. When a fuse on b-ph blows, the voltage on b-phase drops to 320V and the voltage on C-ph drops to 250V, but A-phase remains at ~480V. I would think that if the fuse blows on a certain phase, then that phase voltage would be close to zero and the voltage on the other two phases remain the same.
Can someone explain the theory behind this? Thanks.
Can someone explain the theory behind this? Thanks.






RE: Voltage Loss on Delta Service
The rotating machinery and transformers served by your service will try to recreate that missing phase in a hard to predict way.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Voltage Loss on Delta Service
RE: Voltage Loss on Delta Service
The graph from the monitoring device has 3 channels which would typically represent the 3 phases. Channel 1 measures A-B voltage, Channel 2 measures B-C and Channel 3 measures C-A.
Therefore, Channel 2 is measuring 320V, Channel 3 is 250V and Channel 1 is 480V. Thanks.
RE: Voltage Loss on Delta Service