Is it ok to put fuses after the VFD ? If not, why?
- posted
17 years ago
3 HP Variable Frequency Drive Wiring Question
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- posted
17 years ago
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- posted
17 years ago
But why? The VFD will act quicker than any fuse you can put in there. Also, fuses on the output tend to get hot from the harmonics and if a fuse blows, the VFD will not know it, which means it will continue on supplying power to the motor, which is single phasing now. Better to put the fuses on the input and let the VFD protect the output.
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- posted
17 years ago
I agree on the why question. But most VFD's would trip if one of the output phases open.
What is more common is to use a motor overload relay, not a fuse. The pilot contacts of the relay would be wired such that the VFD is shut off if the relay tripps. This is common where 2 or more motors are connected to one VFD.