Sparkies ?? sizing mcb for compressor

[normspanners]

As always it was a last minute decision to fit it over the weekend coz they had a new pumped pressure wash bath in with a window air curtain cleaner using about 15cfm and were expecting a little 1ph hobby compressor to run it !!

 

[WorkshopChris]

As boards get older the bits are harder to find.
I try to stick to Merlin Gerin now Schneider Electric.

 

[normspanners]

siemens are generally compatible with GE ... I thinkI had two to choose from and yep picked wrong
compressors, fans and pumps etc are a pain to start on Star delta coz they start to work immediately they turn but the load is getting exponentially harder the longer they are running in start , then there is the slight time gap in transition, bit like stamping on the brakes between gear changes in your car which causes a massive spike in the load when, it goes DOL I had one fan that was 40hp and was a killer to start, the transition time had to alter day to day depending 'how it felt' I am sure,
in the end I rigged a resistor closed transition circuit to try to stop it tripping which actually worked fine. But seems ott for a one time start for a compressor.

 

[daleyd]

If it's of any use I have a clamp meter with inrush measurement if you want to borrow it norm.

 

[Gareth J]

Non electrical related thoughts;
-mine came with what I decided was the remains of an oil pressure actuated solenoid to engage/release the unloaders. The pump would not be able to pump unless oil pressure was there.
-could you use the small compressor to fill the tank and fire the unloader solenoid first thing in the morning? Or even rig up a micro compressor to keep it topped up overnight.

 

[normspanners]

If it's of any use I have a clamp meter with inrush measurement if you want to borrow it norm.

Cheers dale I have two clamp ons and one has surge and DC but THANK YOU VM for the offer

could you use the small compressor to fill the tank and fire the unloader solenoid first thing in the morning? Or even rig up a micro compressor to keep it topped up overnight.

Thanks John great minds and all that I had already thought about that and our discussion on yoursbut the oil pressure is up in mil secs so might not help but then would effect the normal running !and yes I had thought about pre filling too !! even 20psi would work IMO but I am working with someone (THEM) who wired up a 3 ph machine and copied the 1ph lift wiring, that was running off 5pin= 3ph +n+e plug using 16a 1ph and wired the 3ph blue to neutral and worse the yellow ph to the earth pin along with the earth cable !! and blamed the machine !! saying it was not working and could not understand how a 1ph machine was wired to a3ph plug !!
If this was me, there wouldnt be an issue.

WOOW
JUST thought CHAPS they maybe switching the pressure switch on / off---- ON first, then throwing the isolator !! because they used to leave the pressure switch on, on the old unit that is how they ( wrongly )used to start the old machine, no matter how many times I told them coz it meant bending over the compressor to get to the pressure switch and the isolator was easy in your face-------- now I have plumbed the pressure switch in your face.
so maybe the supply is being subjected to an isolator start !!!
I thought strange coz I had not had any issues, maybe this is the prob

 

[normspanners]

Well an update They needed a little lesson in how to switch star delta stuff on and off and I couldnt get a c25 managed to get a c32 correct mcb for the board fairly local to me and as per the cable chart it is right on the limit so its some 5x4mm ordered to go in and we can have a neutral in there then.
http://www.rm-electrical.com/wp-content/uploads/2014/11/SWA-Chart-RM-Electrical.pdf
compressor is running fine and had no issues since, they are made up with the difference of having immediate air and it building back up to switch off in 10-15 seconds instead of it taking 5-8mins.
Cheers for the help chaps

 

[Ianb]

start the old machine, no matter how many times I told them coz it meant bending over the compressor to get to the pressure switch and the isolator was easy in your face-------- now I have plumbed the pressure switch in your face.
so maybe the supply is being

GT

 

[skotl]

GT

G&T?

 

[Ianb]

Apologies for post, think I must have been reading this, fell asleep pressed GT and posted by accident!!