ABB ACH550 HVAC speed drive wouldn't turn back on.
after major renovation speed drives on three floors of high-rise building wouldn't turn on.
Is there anything that I don't know? Is there a trick on how to start them after long shut-down?
They have been down for about 2 months and now they are acting as if there was no power to them.
Screen is completely blank, no sounds of cooling fan, clicking of relays or charging capacitor.
I have checked all wiring and voltage levels inside and outside the speed drive, and looked through user's manual.
I thought if you turn the on-off handle on, screen should lit and I should be able to run the motor in hand even if my controls are down.
Have anyone else stumped on it?