using 24vdc from vfd to control relay...

matlark · Nov 17, 2011

Can I do this? I would like to have the 24vdc output on the vfd (abb ach550) power a 24vdc coil, then the start stop can latch using one of the contacts (using push buttons with contact blocks vs. a switch). I contacted ABB and the 24vdc provides up to 250mA. The omron coil draws about 62mA, so it looks like it should work.
thanks

matthew1 · Nov 17, 2011

I'm sure opinions will differ on this. I have used the internal supply before without issues. Never exceed 80% of the supply rating. Only thing that comes to mind for me is no mention of an E-stop. Not sure of the application so that would dictate saftey requirments.

matlark · Nov 17, 2011

For this particular application no E-stop is necassary, just a stop button and a start button.

Lancie1 · Nov 17, 2011

Mat,

Yes, your method will work, but most VFDs have some dry-contact relay outputs (programmable in many cases) that can be used with any external control-voltage supply to latch in a Start-Stop circuit.

matlark · Nov 17, 2011

I was looking at OMRON ly4-dc24, it has power consumption as 1.5 watt. I could have calc'd it wrong but I think it comes out to 62.5mA

matlark · Nov 17, 2011

I haven't used the dry contacts before, would i just wire the NO start button in parallel with the dry contact?

Steve Bailey · Nov 17, 2011

I'm not familiar with your particular model, but many VFDs have a parameter you can set to specify how the the drive deals with start/stop signals. You may be able to have the drive seal in a momentary start command without having to use one of the outputs.

OkiePC · Nov 17, 2011

Yes, Steve is right. I read this thread but it didn't dawn on me what he was doing with the relay until Mr. Bailey posted.

Get the manual for the drive and search for "3 wire" mode. This lets you wire up a normally open momentary button to the start input and a normally closed button to the stop input. The drive will start when the stop input is on and the start input is on. The drive will continue to run after the start input is off as long as the stop input stays on.

No relay required.

I am pretty sure ABB will call that style of wiring 3 wire mode.

EDIT2: Uhhh, maybe not. That manual shows no control wiring, rather its an HVAC drive with a remote keypad module...

EDIT1: ACH550-UH User’s Manual

matlark · Nov 17, 2011

matlark · Nov 17, 2011

see above image, will that work? Relay output closes while running.

Lancie1 · Nov 17, 2011

Yes, except the ACH550 User Manual, Page 1-319, shows the drive Terminal Block numbers for the N.O. dry contact of the Relay 2 to be 22 and 24 (instead of TB14 and TB16 as you have them labeled). Apparently you have a different control board than the one shown in the User Manual.

shooter · Nov 18, 2011

No it will not work to many connections.
The light should go direct to ground on one side and on other side direct to relay from relay to 24 volt.
Now the light will short the start button.

Lancie1 · Nov 18, 2011

Shooter, you are correct. I did not even look at the light, instead checking the new relay seal-in circuit. But as it is, the light resistance will always be parallel to the start button, which could cause a false start command. If it is wired to the Relay TB16 and to -24 VDC, then it should work.

matlark · Nov 18, 2011

So put the light from TB16 to TB4 (GND)?

matlark · Nov 18, 2011

OK... I think I have it. here is an updated pic

using 24vdc from vfd to control relay...

matlark

Member

matthew1

Member

matlark

Member

Lancie1

Lifetime Supporting Member

matlark

Member

matlark

Member

Steve Bailey

Lifetime Supporting Member + Moderator

OkiePC

Lifetime Supporting Member

matlark

Member

matlark

Member

Lancie1

Lifetime Supporting Member

shooter

Member

Lancie1

Lifetime Supporting Member

matlark

Member

matlark

Member

Similar Topics