Disconnect Switch ahead of a VFD??

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bcnj

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I have seen several 480v Air Handlers in a commercial ceiling that a VFD but no Disconnect ahead of the VFD. The VFD has an on/off switch but it was explained to me that a disconnect switch is not required because the On/off switch in the VFD kills the power to the whole unit and VFD itself. They are fed by a dedicated 480v circuit.

Is this correct or do I need a disconnect switch?


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Any opinion on the following code?

430.128 Disconnecting Means.
The disconnecting means shall be permitted to be in the incoming line to the conversion equipment and shall have a rating not less than 115 percent of the rated input current of the conversion unit.


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The disconnecting means can be built into the controller so a VFD with it's own integral disconnect switch does not require a separate disconnecting means.
 
infinity said:
The disconnecting means can be built into the controller so a VFD with it's own integral disconnect switch does not require a separate disconnecting means.
Click to expand...

Most of the small VFDs I see have an electronic on and off that doesn't count as a disconnecting means
 
bcnj said:
I have seen several 480v Air Handlers in a commercial ceiling that a VFD but no Disconnect ahead of the VFD. The VFD has an on/off switch but it was explained to me that a disconnect switch is not required because the On/off switch in the VFD kills the power to the whole unit and VFD itself. They are fed by a dedicated 480v circuit.

Is this correct or do I need a disconnect switch?


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Click to expand...
Different country, different rules, but.......you can't compromise safety.

Apart from any mandatory regulations, how could you safely carry out any maintenance/repair work on the drive or motor?
We'd have to have an approved risk assessment and method statement in place and the supply locked off before we were allowed near the kit.

Failing to do so would get you hung, drawn, and quartered. And banned from site forever.
 
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