merlin gerin master pack

[big bang1]

got 20 acb merlin gerin master packs from 600a to 1200,

i'm new to site and not worked with these before.

how would you maintain one of these, i'm also aware of a weak spring on one of them that has tripped a few times.

we are getting contractors in to see about replacing one of them but eventually as i bed in i'll be expected to carry this out.

 

[Engineer54]

I would suggest that you watch and learn from the specialist technicians as they undertake this work....

EDIT..... By the way, who diagnosed a weak spring??, ...I've worked with these units for many years, and i can't say i've ever known a problem involving a weak spring...

 

[big bang1]

apparently a reseting spring on the side. they are linked in with a stand by generating set. the problem been that after a power cut it did'nt reset its self.

this is what i'm told by the other engineer that knows a bit more than me about these, but he's not around anymore for me to pick his brains. i believe he used to maintaine them he's self before

 

[Engineer54]

Sounds more like the motor drive than the actual spring, i guess they had to manually rack the breaker up in that case. Don't this place hold records of faults and rectifications etc.... like an incident record book type of thing??

 

[big bang1]

there old maintenance company did but in the change over period there were redundancie's and some of the lads wiped computers and binned records so we cant refrence most stuff in the units, some of the lads have started with us but aint electricians even though they are quiete knowledgable with the electrics (know whats happened in past) but would'nt know how to repair or maintane them

 

[big bang1]

my biggest fear is we do call out rotas, i got called out the weekend to it and reset it no problem, but as theres 3 of us at 3 sites we look after1 each and this aint on my site but will have to learn about them for when lads on that site are on sick or on holiday.

 

[Engineer54]

Just to get this straight in my mind, this ACB trips out on no voltage, and the Genny takes over the load when up to speed. When the power comes back the Genny drops out and this ACB automatically via a motor winds up the spring closer and closes the ACB to the load. But it doesn't wind up the spring closer enough to close the ACB, ...Is that right ??

If so, it maybe a simple matter of resetting the spring catch on the holding arm, that is released when manually pushing the ON button or via the auto release solenoid. If you have the maintenance manuals there, it should be able to tell you the procedure. Are these ACBs the withdrawable type?? Most are, and makes working on them that much easier!!!

 

[big bang1]

yeah you got it spot on.

think i need to source the littérateur for these really.

thanks engineer 54 my panic has eased now.

 

[Knobhead]

Just a quick word of warning. Some of the larger MasterPacks have a small front panel hiding a much bigger main body, which means the front of the panel has to come off. So be warned against live terminals.

My only dealings with MasterPacks have been bad ones. A 4000A failed when I tried to rack it back in to the service position. It was just used as an automatic isolator for a 2.6MW induction furnace. After spending a couple of hours trying to get it to work I gave up and decided to short it out. Lucky I’d got 4” X 2½“ copper in the workshop! Shorting out may be drastic but I’d got 100Tonnes of molten iron turning to treacle, it was desperate that we got power back on.
I could think of better things to be doing in the middle of the night.

 

[Engineer54]

Just a quick word of warning. Some of the larger MasterPacks have a small front panel hiding a much bigger main body, which means the front of the panel has to come off. So be warned against live terminals.

My only dealings with MasterPacks have been bad ones. A 4000A failed when I tried to rack it back in to the service position. It was just used as an automatic isolator for a 2.6MW induction furnace. After spending a couple of hours trying to get it to work I gave up and decided to short it out. Lucky I’d got 4” X 2½“ copper in the workshop! Shorting out may be drastic but I’d got 100Tonnes of molten iron turning to treacle, it was desperate that we got power back on.
I could think of better things to be doing in the middle of the night.

Never had much problems with MG's, ACB/GCBs found them very reliable units over a wide ambient temperature range. In fact, can't remember the last large project where MG MV and LV switchgear wasn't specified...

The OP shouldn't come into contact with any live terminals, as i say most of these bigger, higher rated units are of the withdrawable type. So any work done on these units are normally done on the work bench.