Three Phase Power

[Stephen Morrissey]

Hey

Once three phase power is hooked up to a space, how many machines can run off it?

Stephen

[Brett Hanson]

It depends on the size of the electrical service, typically expressed in Amps (at xxxVoltage) or kVA.

[Peter Treston]

(old post I know!, but...)

Machines could also be lowered in power. e.g. we have big 80L machines in football stadiums in the UK, some are only 2kW. I would calculate the heat up time needed and they can turn them on in time for a half time at a match. As a rule of thumb 1kW will heat 10L in 1 hour. So it will take 4 hours to have 80L boiling at 2kW.

Many big brewers will have 3 elements, a service engineer could just disconnect one, but it could cause unbalanced phase issues.

A more risky way would be to be sure not to run machines at the same time, e.g. turn off a brewer while running a dishwasher. Worst to happen should be tripping out, but it could cause other problems. This would be the same as having a double adaptor in a standard 13A socket and just having common sense not to turn on 2 10A appliances at the same time.

A large twin brewer could do 2 full 10L brews in time for a lunch rush. Then you could turn it off, and turn on other appliances.

We have also made high power "preheaters", which are just smallish tanks with a 25kW element in them hidden under a counter with a pressure sensitive pump. The water is heated to around 75C, and then plumbed into smaller 2.8kW plugtop machines, when the small machine calls for water the pressure sensitive pump recognises it and pumps it in. This means the water is heated from 75-95C, rather than the usual 15-95C. That is a 20C increase rather than 80C, so you have in effect increased its output by 4. The inlet solenoids and tubing on the machines would have to be able to handle 75C water though.

This allows you to use the max power of your 3-phase supply, and feed standard 13A plugtop machines which are usually cheaper than a 3phase version, and increase their output hugely.

[Brent]

or just specify the amperage you require per phase...

in a worst case (especially for temporary requirements) you just see thicker three phase cable running to where you need / want it.

Don't know about the other parts of the world, but in NZ as soon as you exceed 55(?) amps per phase you go to different connectors which is something else to consider.

Temporary power normally comes with break out boxes to give the correct outlets for your requirements

Also remember that three phase is for motors, so if you are just running power hungry devices the loading across the phases is not important... but balancing the load so you don't exceed and trip one phase is.

I have never had a problem acquiring power delivery of the required amperage in either three or single phase.

Remember that most coffee machines don't actually need three phases, rather lots of power - which can be delivered from a single phase if necessary.