I use this VFD to check out 3 phase motors after converting from star to delta. Last time I used it, it was fine. This afternoon I connected up a motor and switched on, the usual rDy (ready signal) was displayed. Flicked the forward run switch and nothing except the display showing zero Hertz, same with reverse switch. Checked out the motor on a second Altivar and it ran perfectly. So it seems the little old Altivar 11 has a problem.
I checked out every parameter in the program (against my list of value) nothing had changed. Checked that the common output voltage for digital inputs were present. Yes +15 Volts was present and the mechanical switches worked as they should.
Now these all singing and dancing VFDs are usually fast enough to tell you what the fault condition is (usually motor fault) but often VFD problems as well. But not this time!
Not sure where to check next, but it seems that the switch digital inputs pull the +15 Volt common supply to zero if it is connected to an analogue input. Now this can't be correct?
Andrew.