# ACS400 Won't Start Remotely



## Zana (Jul 25, 2014)

Been working on an ABB ACS400 unit that refuses to start remotely. We're using a siemens BAS to send commands to the unit, but their tech is saying everything is working on their end. It's in a air handling lead/lag/standby set up. Basically it starts up if one of the other units its in standby for fails. The drive is showing no errors and we have a reference signal from the BAS. However, if we drop one of the air handlers that it's supposed to be the make up for, the drive isn't starting in Auto/Drive like it's supposed to. It was working in bypass until we managed to destroy the contactor yesterday.

Anyone have any clue as to where to look to find out where the signal maybe missing at? The HOA switch on the front looks dodgy and I only had 120 volts on the bypass side of the switch. When switching to drive/auto, I wasn't reading any voltage across the contacts at all so I am wondering if maybe the switch isn't actually being put into Drive/Auto like it's supposed to be.


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## Zana (Jul 25, 2014)

BTW, I have 0 wiring diagrams for the interior of the cabinet, so I am essentially doing this all blind. Where I work, they aren't real big on documentation.


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## Cow (Jan 16, 2008)

Have you looked on ABB's site for a drive manual? That's where I get mine when I need them, they're in pdf. I download them to a flashdrive.


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## John Valdes (May 17, 2007)

There is a digital input to command the start and there is a signal or digital contact to command speed.
I am not familiar with this drive, but there should be a screen where you can see all the inputs and outputs and what state they are in.
The command to start should be true and you should be able to toggle this input to verify the drive is indeed seeing the input.
If you verify this input is working, then its time to look through the parameters and see why it s not taking off. 
Like Cow said, get a manual.


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## Zana (Jul 25, 2014)

First off, the manuals have jack about the control wiring outside the unit and not having the actual wiring diagram that came with the enclosure and drive from the factory makes it difficult to trace out signals.

That said, while installing the bypass contactor I found a loose control wire on the load-side of the isolation contactor. Torqued it down, turned the HOA switch to drive and it pulled in. Drive responded as it should when switched to lead and worked.


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## John Valdes (May 17, 2007)

Zana said:


> First off, the manuals have jack about the control wiring outside the unit and not having the actual wiring diagram that came with the enclosure and drive from the factory makes it difficult to trace out signals.
> 
> That said, while installing the bypass contactor I found a loose control wire on the load-side of the isolation contactor. Torqued it down, turned the HOA switch to drive and it pulled in. Drive responded as it should when switched to lead and worked.


Actually every drive manual does show external wiring schemes.
Drives in most cases have their own power supply and a control terminal strip. 
To this strip is where you connect your inputs and outputs.
These are all clearly drawn in the manual.

Who cares where the wires go outside the cabinet for testing purposes?
If you can make the drive operate from the keypad or with a test switch, you can easily find out if its a wiring problem or a drive problem.

Some places have good documentation and some don't.
When I needed a print and did not have one, we made a new one.

I am glad you found your problem. You got lucky.


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## Zana (Jul 25, 2014)

John Valdes said:


> Actually every drive manual does show external wiring schemes.
> Drives in most cases have their own power supply and a control terminal strip.
> To this strip is where you connect your inputs and outputs.
> These are all clearly drawn in the manual.
> ...


Not sure what VFDs you have, but the ones we have talk about the unit itself in the manual, how to program and install it, and what control terminals do what. Once those control wires leave the actual VFD, there is nothing in the manuals telling you where they go, what ice cube relay they're connecting to, etc. Here you have to physically follow the wires to each component outside the VFD in order to trace anything. I have about 968 VFDs I am responsible for doing maintenance on (from about 6 or 7 different manufacturers, some ranging from brand new to 15+ years old) and repairing and I am the only controls mechanic this place has, believe it or not. I have very little time I can spend on one VFD before another more critical system demands my attention. So having that complete wiring diagram would be nice so I don't have to waste time physically pulling wires out to find out where they connect outside the VFD.


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## denny3992 (Jul 12, 2010)

Zana said:


> First off, the manuals have jack about the control wiring outside the unit and not having the actual wiring diagram that came with the enclosure and drive from the factory makes it difficult to trace out signals. That said, while installing the bypass contactor I found a loose control wire on the load-side of the isolation contactor. Torqued it down, turned the HOA switch to drive and it pulled in. Drive responded as it should when switched to lead and worked.


Nit related but
How did u install the bypass contactor?


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## Zana (Jul 25, 2014)

denny3992 said:


> Nit related but
> How did u install the bypass contactor?


Easy. Took out the control wiring, after labeling where they go of course. Unbolted it from the enclosure, unattached it from the isolation contactor because they were attached at the side. Reverse that for putting it back in. Contactor was exactly the same as the old one, just new. All in all, took maybe half an hour because the fit was tight.


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## John Valdes (May 17, 2007)

Zana said:


> Not sure what VFDs you have, but the ones we have talk about the unit itself in the manual, how to program and install it, and what control terminals do what. Once those control wires leave the actual VFD, there is nothing in the manuals telling you where they go, what ice cube relay they're connecting to, etc. Here you have to physically follow the wires to each component outside the VFD in order to trace anything. I have about 968 VFDs I am responsible for doing maintenance on (from about 6 or 7 different manufacturers, some ranging from brand new to 15+ years old) and repairing and I am the only controls mechanic this place has, believe it or not. I have very little time I can spend on one VFD before another more critical system demands my attention. So having that complete wiring diagram would be nice so I don't have to waste time physically pulling wires out to find out where they connect outside the VFD.





Zana said:


> Easy. Took out the control wiring, after labeling where they go of course. Unbolted it from the enclosure, unattached it from the isolation contactor because they were attached at the side. Reverse that for putting it back in. Contactor was exactly the same as the old one, just new. All in all, took maybe half an hour because the fit was tight.


So it was just a bypass change out?
You did not have to figure out how it worked? Or use the manual to see how its connected? Just replaced the old one?
This should have been your clue as to why the new one did not work.

On the wiring. The control terminal strip connects the drive to the outside world. 
I can assure you, the drive manual is all you need to determine if the drive is at fault or if the external wiring or devices are at fault.
Think of a start, stop or jog button as an example drawn in the drive manual. 
Is this not a print of how its supposed to work? If for example terminals 5 & 8 must be closed for forward, would that not be all you need to follow that circuit out? Or to just see if the input is true/on?
No matter where the wires go. The manual shows you what must happen for any given command.

Does not matter if the drive inputs are present from relays, push buttons or contacts.
The drive manual does show exactly what must be closed or open for any given command. No matter where the command comes from.


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