got a weird one...intermittently drive wont autotune at all, just shuts off arm over current...sometimes it ramps up halfway to max (100hp-190 amps) before autotune fail, twice its popped incoming fuses on drive...drives obsolete, they swapped several times, same condition...called me down, suspected power issue(know opening power under load they can pop) and found a lug burnt completely off the 118kva transformer tap- how it was running at all still bugs me as it had 450-460 which did seem a bit low, but it had all three phases... checking voltage under load saw one lag drop before it tripped out, aha...bad transformer...
anyways I got a known good set of firing and logic cards from a running machine, tested gated all the SCRS individually, no issues, reassembled, replaced fuses, hooked up our old Fluke power monitor to record voltages/currents(but its not super fast)and twice, near instant trips at autotune, third time it ramped up over 100 amps and tripped, tried twice more watching different things, and last time it tripped main 200a breaker to transformer and blew two drive fuses...
this things driving me nuts...maintenance has swapped motor several times, drive several times before i found the transformer issue, yet its still doing the same thing? all I can think of is pull the bussbox and check for a bad contact/loose wire, etc up there..,.just sure seems if something had arced in the main ceiling buss, it woulda blown up in a very noticeable way...
Anyways- anyone out there ever had armature autotune issues like this? think power dropping under loads makes sense? what bugs me is the fluke monitor didnt catch anything, but it may be way too slow compared to a semiconductor fuse- and I had it connected at transformer secondary just due to accessibility...
weve had probably 100 of these 100hp drives in use, never seen such a thing...think it has to be feed related.
gonna have them pull the plug from the bussway, but I dont want it touched till main buss can be switched off first...*if* plug is damaged, dont want any chance of blowing the buss...will have to wait till weekend...
anyways I got a known good set of firing and logic cards from a running machine, tested gated all the SCRS individually, no issues, reassembled, replaced fuses, hooked up our old Fluke power monitor to record voltages/currents(but its not super fast)and twice, near instant trips at autotune, third time it ramped up over 100 amps and tripped, tried twice more watching different things, and last time it tripped main 200a breaker to transformer and blew two drive fuses...
this things driving me nuts...maintenance has swapped motor several times, drive several times before i found the transformer issue, yet its still doing the same thing? all I can think of is pull the bussbox and check for a bad contact/loose wire, etc up there..,.just sure seems if something had arced in the main ceiling buss, it woulda blown up in a very noticeable way...
Anyways- anyone out there ever had armature autotune issues like this? think power dropping under loads makes sense? what bugs me is the fluke monitor didnt catch anything, but it may be way too slow compared to a semiconductor fuse- and I had it connected at transformer secondary just due to accessibility...
weve had probably 100 of these 100hp drives in use, never seen such a thing...think it has to be feed related.
gonna have them pull the plug from the bussway, but I dont want it touched till main buss can be switched off first...*if* plug is damaged, dont want any chance of blowing the buss...will have to wait till weekend...