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Electrical Connection for VFD (Variable Frequency Drive)

Electrical Connection for VFD (Variable Frequency Drive)

Electrical Connection for VFD (Variable Frequency Drive)


Hello Sir/Madam,

Please help me in connecting a (250V~ door Switch) of Air Handling Unit motor cabinet with the ON/OFF VFD(Variable Frequency Drive) command relay(24V~).

Now my basic, question is that I need to make such a combination that when Motor cabinet door opens the motor VFD relay gets OFF command lead to stopping of motor itself & vice-versa. If possible please suggest me some relevant tips or ideas to do so.

Thank You...

RE: Electrical Connection for VFD (Variable Frequency Drive)

Interface relay or multi-pole switch.

RE: Electrical Connection for VFD (Variable Frequency Drive)

Use a second door switch: Use the VFD's low voltage control output supply to the second switch and back to the VFD's 'run' input screw. Then set the VFD's parameters correctly to recognized an input "run" signal.

Or, as Scotty suggested use a relay. This will require some power to run its coil thru the existing door switch. Then use one set of contacts to continue the current function the door switch is doing and a second set of contacts to do what I described above. Make sure you use the relay's normally open sets of contacts so if the power to the coil is interrupted for any reason the relay opens like the door opened to keep things safer.

And yes you can use two different voltages on a relay's contacts.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Electrical Connection for VFD (Variable Frequency Drive)

#ScottyUK (Electrical) & #itsmoked (Electrical)

First of all sorry for delay in reply. But thanks Sir I work on this project with this concept & will revert back with the results soon.bigsmile

Also I want to ask that "If I connect 250V ~ supply to 24V~ supply to relay then it wouldn't burn due to over current passing through its coils?"

RE: Electrical Connection for VFD (Variable Frequency Drive)

Umm. You cannot do that. The coil will require one voltage and one voltage only. You must pick the appropriate one for your situation. The contacts can be different voltages or more likely different circuits.

I suggest you should find someone local who's done this type of stuff and get them to help you.

Keith Cress
kcress - http://www.flaminsystems.com

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