Linking two bigger compressors ?

[W.olly]

I have done this before but with smaller compressors. Now as these are a lot bigger than i had before i was wondering how to power them. I am running one from a 32amp MCB. Also just checked the motor specs and there slightly different. No big deal i dont think.. ?

The one i had originally has this motor which is a replacement

Then one i collected today has this original motor fitted.

Garage is running from a 62amp DP rcd CU in the workshop ( 10mm T&E ) and feeding the 40amp MCB. CU in the workshop which i6s then fed from the 32amp MCB to the 16 Amp Interlock Socket for the compressor/s

Whats best way to run them together then with what i have? Have a twin Interlock so each compressor can run from the 40amp MCB ? saying thsi as both compressors add upto 26.6amp so a 16amp Interlock is no good ...yes ?

 

[Erie Fred]

They make a circuit "over here" for just what you want.
IIRC you can set them to alternate witch one runs first, both if the air supply demands it, etc.

 

[W.olly]

They make a circuit "over here" for just what you want.
IIRC you can set them to alternate witch one runs first, both if the air supply demands it, etc.

I had my last set up to run with one kicking in just before the other but was a reat faff to set them up. i was running them off a 13amp plug as its all i had at the time. I had to adjust shut off. IS that what you mean ?

 

[brightspark]

they will both run of a 30 amp supply but you will have to fit a delay timer to the start of the second compressor by about 5 seconds . you fit a switch in the second contactor so you can just use the one if needed

 

[hotponyshoes]

they will both run of a 30 amp supply but you will have to fit a delay timer to the start of the second compressor by about 5 seconds . you fit a switch in the second contactor so you can just use the one if needed

That's how sparky wired mine up.
Only one pressure switch for start/stop and then one starts about 10 seconds after the other which saved me running a bigger cable across the workshop.
Each have electrical and air isolation so can just run one if required

 

[MetalMonkey]

You can feed both from a 32A circuit. I run my two 3hp units from a single circuit which is then split into two 16A supplies via a couple of MCBs in a breakout box. Each compressor uses its own pressure switch, but they don't switch on together. You can often tweak them if you find that they do.

Timed delay on one pressure switch would also work, but just consider how the unloader will work on each compressor.

 

[Erie Fred]

I had my last set up to run with one kicking in just before the other but was a reat faff to set them up. i was running them off a 13amp plug as its all i had at the time. I had to adjust shut off. IS that what you mean ?

No, I'll try to find it.
Was a purpose made control.
IIRC the sprinkler system people use them
Every time the compressor came on, it could alternate the master & secondary unit.
to even out the wear, It had the hour meters for each on this panel.
The pressure switch was on this box, it determined when each one came on.

 

[Turbo]

I had the cut in pressure on one unit set 10psi below the other one, ran like that for years no bother.

But I only had the 2nd unit on if I needed lots of air, for day to day use one was enough.

 

[W.olly]

I had the cut in pressure on one unit set 10psi below the other one, ran like that for years no bother.

But I only had the 2nd unit on if I needed lots of air, for day to day use one was enough.

tats it, it, that was like my last set up, as run from 13amp plugs. It mite of been the compressors i was using but my god it was a fiddle to set then up.

 

[W.olly]

So this would work. for ease.

From the 40amp MCB to the 16amp socket.. Connect a two way splitter so both compressors can be plugged in. Then like i did before, run them and see when they kick in and have one a few seconds after.

@Turbo same as you ?

 

[MetalMonkey]

So this would work. for ease.

From the 40amp MCB to the 16amp socket.. Connect a two way splitter so both compressors can be plugged in. Then like i did before, run them and see when they kick in and have one a few seconds after.

@Turbo same as you ?

32A MCB to 32A socket, then split into two 16A, each protected with a 16A MCB

Or two 16A MCB run in two new circuits, one for each compressor.

 

[Morrisman]

Strangely enough, two smaller compressors is a cheaper way to effect a certain CFM, than buying one big one.

 

[Turbo]

So this would work. for ease.

From the 40amp MCB to the 16amp socket.. Connect a two way splitter so both compressors can be plugged in. Then like i did before, run them and see when they kick in and have one a few seconds after.

@Turbo same as you ?

Yep.

Adjusting the cutout was as simple as turning a nut inside the pressure switch until the desired cut in pressure is reached. You have to drain out some air until the pump comes on, check the pressure and let it fill with air again before making another adjustment.

 

[AVI_8]

they will both run of a 30 amp supply but you will have to fit a delay timer to the start of the second compressor by about 5 seconds . you fit a switch in the second contactor so you can just use the one if needed

@brightspark any chance you could point to a link for the delay switch which would be suitable for this, thanks.

 

[KemppiFrog]

@brightspark any chance you could point to a link for the delay switch which would be suitable for this, thanks.

I wouldn't bother, just set the pressure switches to sequence.
W.olly your avator has car now, thought boats were your thing??? What is it?

 

[AVI_8]

I wouldn't bother, just set the pressure switches to sequence.
W.olly your avator has car now, thought boats were your thing??? What is it?

I know that regarding the pressure switches, just thought that by doing what brightspark said it would represent what is replicated on a dual pump compressor and would be a better set up, one pressure switch with one starting and a time switch to start the second one seconds later, would guarantee sequential starting without having to change any settings.

 

[KemppiFrog]

I know that regarding the pressure switches, just thought that by doing what brightspark said it would represent what is replicated on a dual pump compressor and would be a better set up, one pressure switch with one starting and a time switch to start the second one seconds later, would guarantee sequential starting without having to change any settings.

I was just thinking about the 3X load when each compressor kicks in, so staggering them to avoid overloading the supply.

 

[JOEPRO]

My tandem compressor has a control box which basically delays one of the motors after switch on to save the startup loading current.

That is a situation you will have when the tanks are empty! Both motors will start even if the pressure switches are on / off different pressures. Because low pressure means both will start at once. A delay timer on one of the motor controls prevents both from starting together. There is also only one unloaded valve/ solenoid switch required in this setup.




Simple enough setup. It's also possible to easily turn off one of the motors if desired.

 

[brightspark]

same setup as the one i have 2 motors 2 contactors one delay timer on second motor and only one pressure switch on a 32 amp supply

 

[AVI_8]

same setup as the one i have 2 motors 2 contactors one delay timer on second motor and only one pressure switch on a 32 amp supply

Give us a heads up on the delay timer, is it something you can buy or do you need to be a spark to make one … just for us who are not electricians.