3 phase supply size

[James sparks]

Hi all,

I need to put in a 3 phase supply for a piece of equipment in a commercial unit. They've sent the spec sheet for the item over and all it says is

Current type (Ph/V/Hz): 3/420/50
Power rating (kW): 7.8


I just want to clarify if it's 7.8kW per phase or 7.8kW total over all 3 phases.

Thanks!!

 

[uksparks]

I would imagine it's in total not per phase.

 

[Darkwood]

usually if you use a kw rating in the same spec as 3ph its per phase ...

 

[uksparks]

I suppose the best thing would be to get more data from the device

 

[micknew]

I would imagine it's in total not per phase.

I agree with you.
If not it should have said 'per phase.

 

[James sparks]

[h=3]Technical data[/h]
Current type Ph/V/Hz		3 / 420 / 50
Flow rate (l/h)		500 - 1000
Pressure (bar/MPa)		30 - 200 / 3 - 20
Max. temperature (°C)		155 - 80
Power rating (kW)		7.8
Consumption fuel oil (kg/h)		6.4
Fuel tank (l)		25
Fuel tank (cc³)		-
Weight (kg)		171
Dimensions (L x W x H) (mm)		1330 x 750 x 1060
Detergent tank (l)		20

 

[micknew]

That is telling you that the total load of the machine is 7.8KW.

 

[uksparks]

So it's 7.8kW split across phases, so not much then, what is it you say? A pump?

 

[Darkwood]

its per phase 7.8kw per phase otherwise it would have stated single

 

[micknew]

its per phase 7.8kw per phase otherwise it would have stated single

No it wouldn't.

 

[Darkwood]

If you have a spec asking fot 3ph and a Kw rating its Kw per phase .. . no disrespect to other posters but your guessing and not experienced in 3ph so express this in your post or you may mislead the OP ... I assume a 3ph device is part of the setup like a motor; motors are specd per phase not devided by 3..

 

[NickD]

No it wouldn't.

I would ask the question of the supplier/manufacturer/whoever. Assumption is the mother of all cock ups.

 

[micknew]

If you have a spec asking fot 3ph and a Kw rating its Kw per phase .. . no disrespect to other posters but your guessing and not experienced in 3ph so express this in your post or you may mislead the OP ... I assume a 3ph device is part of the setup like a motor; motors are specd per phase not devided by 3..

You are wrong and most of my work is industrial 3 phase.

 

[Darkwood]

You are wrong and most of my work is industrial 3 phase.

If you request a supply from DNO in Kw then its per phase.
If you get a motor and it says 4kw 400v then its per phase.
If you have a machine that asks for a 3ph supply 10kw then thats per phase.


25yrs of industrial intalls design and machine panel building plus several requests to DNO for supplies or upgrades im sure im not wrong....

Only exception is the occasional machine usually from china and 2nd hand that does go over 3ph and checking the wiring plan or load characteristics can usually identify this but other than that ill say your wrong.

Its always good to cross check these values Ive seen architects mess up if a reading is in KVA on a machine or supply then its likely to be a total demand across the phases as dave points out below but the OP spec'd a Kw value.

 

[davesparks]

Consider a 32A three phase mcb, that's 32A per phase. Same goes for KW rating.

Only fly in the ointment I can think of is from UKPN's paperwork where a 100A 3ph supply is described as being a 69KVA 3ph supply.

 

[Darkwood]

Consider a 32A three phase mcb, that's 32A per phase. Same goes for KW rating.

Only fly in the ointment I can think of is from UKPN's paperwork where a 100A 3ph supply is described as being a 69KVA 3ph supply.

Good point Ive come across before very confusing TBH when the rest of the industry works the other way.

 

[Guest111]

I would have said KW per phase myself,hazarding a guess I'd say it's some kind of pressure washer and you can get some very large ones with a fair old inrush on the motor.

 

[Spoon]

Are you intending to use a DOL starter? If not then what?

 

[Guest111]

Are you intending to use a DOL starter? If not then what?

It may well have it's own control gear built in,It would have been nice if the op had actually told us what the machine was.lol

 

[Spoon]

It well could have, but then it should have a label on stating what it requires. Us leccies know everything except when it comes to the opposite sex..