Fault Relay concept in ABB VFDs

Histor (Electrical)(OP)3 Sep 24 02:18

' ABB ACH580 VFD drive we have output relay which I'm using for fault signal... I'm using fault(-1) option means inverted fault .. My understanding is that..'
I have the following suggestion for your consideration. Please check and verify whether in order.
1. The ABB manual states "default i/o connection, but does NOT elaborate on "Fault (-1) means inverted fault". This is the root cause.
2. I tried to look at it as following:
a) VFD off, contact (25-27) = Close. Please Check !,
b) VFD on, healthy, contact (25-27) = Open,
c) VFD on, faulty, contact (25-27) = Close,
d) VFD on, fault reset, contact (25-27) = Open,
Note: 1. When switching on the power, healthy condition, Contact (25-27) change over from Close to Open,
2. This means that switching off a healthy VFD, contact (25-27)= Close. This is going to indicate "Fault"? Check !
Che Kuan Yau (Singapore)

It's been years since I have programmed an ABB drive, but I believe you have that correct. In the "inverted" operating state (-1), the NO contact would be held closed when "normal" and drop out (open) when there is the fault that you programed it to.

As I recall though, when the drive is POWERED DOWN, and until it FINISHES powering up, that relay ALSO drops out. I recall this because it was something I hadn't considered when using it that way, so my SCADA system was getting a fault at least twice per day when they powered down, which in some cases when there were utility issues or safety shutdowns, filled the fault code buffer (that was a long time ago when that buffer only held the last 4 faults).Might not be a problem, but it's something to think about.


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