Newbie- Magnetic contacts and AC drives

[oxford]

I was looking at Ac drives and the their peripheral electronics.

What role do the magnetic contacts play?

Do you need a emf line filter?

Is it ok to step up 110V to 220V to meet drive voltage requirements?

Thanks

[Al_The_Man]

Not quite sure of the questions, but for VFD's often the manufacturer will recommend three phase chokes or reactors, in some cases I have fitted them on the input and output.
Most hobbiests do not bother it seems.
Magnetic contactors? These are uses to disconnect three phase power to the VFD input, never between VFD and motor.
They are usually picked up when the E-stop is released to put the VFD in the ready condition.
There is usually nothing wrong with raising the voltage by transformer for example, if the VFD warrants it, keep in mind the 120v current will be double the 240v current draw.
Al.

[oxford]

I think that answers the question.

Here is an image of the wiring of a drive that I was talking about

Thanks

[oxford]

Anyone know of a good source for magnetic contacts?

Thanks

[Al_The_Man]

You can pick up Telemecanique contactors off ebay, the DIN style DIN rail mount are nice and compact.
Other makes are Allen-Bradley and Square D etc.
Al.

[oxford]

How important is it for the contactors to have surge suppressors?

[Al_The_Man]

If you mean RC snubbers across the coil, I would recommend it for AC coils and reverse diode for DC coils.
Al.

[oxford]

Are there any type of Contactors that are not compatible with a RC snubber?

[Al_The_Man]

An RC snubber goes across any contactor coil if it is AC, A DC coil takes a reverse EMF diode.
Al.

[oxford]

Is the RC snubber type determined by ac voltage?


Thanks

[Al_The_Man]

Previous link.
http://cnczone.com/forums/showthread...hlight=snubber
The capacitor max voltage rating has to exceed the applied voltage.
The values can change according to the energy stored in the device.
The one shown is good for the average solenoid and most DIN style 3 ph contactors.
Al.

[oxford]

In the AC servo drive set up, there is a Molded Case Circuit Breaker before the Magnetic Contact. Is it possible to just use the right rated circuit breaker that can be found for cheap at the hardware store... The kind you find in your basement fuse box?

Thanks