Can I run a 5.5hp compressor...

[julianthegypsy]

On a 16 amp 3 phase supply? I need a bigger compressor for my plasma table. The one I have is a 2hp 3 phase Clarke that came with the workshop and it's too slow. I have a 3 phase socket right where I want it but I'm really short of ordinary 240volt sockets, so I want to stay with 3 phase. Looking secondhand, I'm seeing a few 5.5hp compressors but I'm not sure that 16 amps is enough. I'd be happy with 4 or 5hp to be fair, but I'm not seeing them in 3 phase, at least, I haven't seen any good ones!

 

[knighty]

yes, easily :-)

10hp should be no problem.... 15hp is the max limit, pushing your luck a bit at 15hp


need to check the fuse for the socket, in case it's not rated for starting motors (assuming it's an MCB) but it's not a big deal to swap that :-)

 

[julianthegypsy]

yes, easily :-)

10hp should be no problem.... 15hp is the max limit, pushing your luck a bit at 15hp


need to check the fuse for the socket, in case it's not rated for starting motors (assuming it's an MCB) but it's not a big deal to swap that :-)

The socket is currently running the motor on the 2HP compressor, so it will start motors, assuming the breaker is ok. I can easily get a breaker changed, as long as I'm within the capacity of a 16 amp plug, because I doubt I could get it changed to a 32amp socket.

 

[brightspark]

your new motor would have to be no more than 16 amp current draw each phase

 

[8ob]

I dont think I have ever used any of the 32amp three phase sockets here, the 16amp three phase sockets are on all the welders compressors ,machines etc and have never popped a breaker.

Bob

 

[julianthegypsy]

your new motor would have to be no more than 16 amp current draw each phase

Yep, that I understand. What I wasn't sure of was what's the biggest motor that 16 amps will handle. Also, if I got a (let's say) 4hp single phase motor, could I wire it into one phase of the three phase plug?
Thanks for the replies by way, it's really helpful!

 

[brightspark]

Yep, that I understand. What I wasn't sure of was what's the biggest motor that 16 amps will handle. Also, if I got a (let's say) 4hp single phase motor, could I wire it into one phase of the three phase plug?
Thanks for the replies by way, it's really helpful!

no a 3hp single phase would would need a 16 amp breaker

 

[julianthegypsy]

no a 3hp single phase would would need a 16 amp breaker

Wouldn't the three phase 16 amp socket have a 16 amp breaker?

 

[brightspark]

Wouldn't the three phase 16 amp socket have a 16 amp breaker?

yes but that would limit using it on a single phase motor to 16 amp max. if it was a 3 phase motor it would run a larger motor because 3 x 16 amp so 48 amp

 

[julianthegypsy]

yes but that would limit using it on a single phase motor to 16 amp max. if it was a 3 phase motor it would run a larger motor because 3 x 16 amp so 48 amp

Gotcha. So I could potentially run say a 4hp single phase machine, which I reckon would be safely under sixteen amps, or easily run a 5.5hp three phase machine, or from what you're saying, even a 7.5hp machine. I've just spotted an ABAC 5.5HP going for £295 and I'm a bit tempted..

 

[brightspark]

if you keep it at 415 volt 3 phase you could run up to 10hp giving it 7.5 kw and run on the 16 amp breaker. on single phase only up to 3hp on a 16 amp breaker

 

[8ob]

Gotcha. So I could potentially run say a 4hp single phase machine, which I reckon would be safely under sixteen amps, or easily run a 5.5hp three phase machine, or from what you're saying, even a 7.5hp machine. I've just spotted an ABAC 5.5HP going for £295 and I'm a bit tempted..

Thats what I am running, kin noisy blighter and needs to live out.

 

[julianthegypsy]

Thats what I am running, kin noisy blighter and needs to live out.

Annoyingly, I have nowhere outside where I could put mine. Well, not without incurring the wrath of my landlord! I'm waiting for him to shift his old milling machine then I'll look at a sound insulated box for whatever compressor I end up with.

 

[julianthegypsy]

I've just seen a three phase, 3kw (4hp) compressor with a 120litre tank that looks good. Claimed 14cfm, which sounds about right and should stay on top of the plasma. I'd go for a bigger tank but I'm short of space. Is there much downside to a smaller tank?

 

[fizzy]

Be wary of enclosures. They can cause the compressor to get far too hot unless well designed.

 

[carbon]

I'd go for a bigger tank but I'm short of space. Is there much downside to a smaller tank?

A bigger tank doesn’t gain you any more cfm when used for long periods

 

[julianthegypsy]

It won't be enclosed. If I end up enclosing it, it'll have ventilation ducting to the fan and an exhaust, probably with another fan on it to keep it cool. Years ago, I installed a single cylinder diesel generator in a house in Indonesia that was being used as an office. When the boss visited from Singapore he started ranting about us not having sorted the power supply... until I pointed out that the office was currently running off the generator which was in the room next door...

 

[julianthegypsy]

A bigger tank doesn’t gain you any more cfm when used for long periods

The one I have currently is two HP and doubly annoying because apart from not keeping up, it's a 150 litre tank, and if it's at say 7 bar, it will run for a couple of minutes then I have to stop the cutter and wait ages till it fills the 150 litre tank!
I wondered if the smaller tank would mean the air would be hotter and consequently have more condensation but this one looks to have a big cooler on the side...

 

[ukracer]

A bigger tank doesn’t gain you any more cfm when used for long periods

What's the point in a bigger tank?

 

[brightspark]

What's the point in a bigger tank?

it will give you a longer burst of air before it drops in pressure then it takes twice as long to fill so it has its use