Star/Delta Fun!!!
Well late today (friday) I was working on a lift here in CHCH (I work for a major lift company here)
it was a hydraulic lift, with a PLC based controler (in other words, one of those CHEEEAPPPP shitty lifts)
apperantly cheap enough to not bother with a mechanical interlock on their Star/Delta Contacters,
andway, because of the freaky PLC controler we couldnt get the lift off the buffers (we had sunk it till it was sitting on the buffers)
se we manualy started the hydraulic pump, which involves 2 people I was in charge of the main contactor and the delta, my workmate was in charge of the star contactor, first time it went fine, we started the pump ok, managed to mopve the lift nowhere (it was a unfamiliar valve block on this hydraulic)
it seemed we needed to energise a valve to get the lift to start to move up, so we changed our wiring to open the valve when the motor went Delta........
so we start again, We get the motor started on star, I then get my work mate to release star so I can press in delta,. but I'm a bit too fast, and manage to push it in before he has released the star contactor
Well.. that means we have a Direct 400V short...
BOOM!!!!!!!
we're greeted by a huge blue flash, lots of smoke, and flying peices of molten copper in all directions.. 15 minutes before knockoff time.
se we spent some more hours there replacing contactors, which arnt cheap BTW.......
and my nice Stylich Bolle Safty glasses are fucked now too, they have spots of molten copper embedded them now :(
well hey, better that than my eyes
it was a hydraulic lift, with a PLC based controler (in other words, one of those CHEEEAPPPP shitty lifts)
apperantly cheap enough to not bother with a mechanical interlock on their Star/Delta Contacters,
andway, because of the freaky PLC controler we couldnt get the lift off the buffers (we had sunk it till it was sitting on the buffers)
se we manualy started the hydraulic pump, which involves 2 people I was in charge of the main contactor and the delta, my workmate was in charge of the star contactor, first time it went fine, we started the pump ok, managed to mopve the lift nowhere (it was a unfamiliar valve block on this hydraulic)
it seemed we needed to energise a valve to get the lift to start to move up, so we changed our wiring to open the valve when the motor went Delta........
so we start again, We get the motor started on star, I then get my work mate to release star so I can press in delta,. but I'm a bit too fast, and manage to push it in before he has released the star contactor
Well.. that means we have a Direct 400V short...
BOOM!!!!!!!
we're greeted by a huge blue flash, lots of smoke, and flying peices of molten copper in all directions.. 15 minutes before knockoff time.
se we spent some more hours there replacing contactors, which arnt cheap BTW.......
and my nice Stylich Bolle Safty glasses are fucked now too, they have spots of molten copper embedded them now :(
well hey, better that than my eyes