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3 phase electric HELP

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cqueen

Original Poster:

2,118 posts

122 months

Saturday 10th September 2011
quotequote all
I have bought a piece of machinery that runs on 3 phase. In true PH style I thought - 'Simple I'll just buy a converter'. Now bearing in mind I don't even know what 3 phase is/does smile - I need some help.

So to help figure out what I need, the machine has 4 motors each rated at 0.37Kw.

Convert Kw to HP =

0.37Kw x 4 motors = 1.48Kw (x) 1.34 = 1.98hp

Now that's just the power to the motors, what about the little light bulb and electrics for the switches/digital displays?

Would a 2hp static converter be ok? Are static converters silent (or at least quiet)?

Thanks



Blakeatron

1,546 posts

75 months

Saturday 10th September 2011
quotequote all
4 motors? sounds good what is it?

Cant help sorry, but I thought I could change one of our machines once - I got it wrong and it hurt

cqueen

Original Poster:

2,118 posts

122 months

Saturday 10th September 2011
quotequote all
Blakeatron said:
I got it wrong and it hurt
Physically or financially? smile

hidetheelephants

11,057 posts

95 months

Saturday 10th September 2011
quotequote all
There are a variety of ways of running 3 phase machines;

  1. Using 3 phase leccy direct if it's available; commercial premises often have it, residential tend not to.
  2. Rotary converter; noisy and inefficient.
  3. Static coverter; expensive for what it is and bulky.
  4. VFD inverter; whizz bang electronic wizardry, you can vary the motor speed and all sorts.
Machine Mart flog rotary and static converters and there are a number of online dealers who specialise in phase converters for domestic use of 3 phase machines. There are VFDs on ebay but you need to know what you're doing if it doesn't come as a turn-key non-electrician friendly package.

what's the machine? 4 half horse motors sounds like some kind of deviant woodworking multitasking wonder device.

cqueen

Original Poster:

2,118 posts

122 months

Saturday 10th September 2011
quotequote all
hidetheelephants said:
There are a variety of ways of running 3 phase machines;

  1. Using 3 phase leccy direct if it's available; commercial premises often have it, residential tend not to.
  2. Rotary converter; noisy and inefficient.
  3. Static coverter; expensive for what it is and bulky.
  4. VFD inverter; whizz bang electronic wizardry, you can vary the motor speed and all sorts.
Machine Mart flog rotary and static converters and there are a number of online dealers who specialise in phase converters for domestic use of 3 phase machines. There are VFDs on ebay but you need to know what you're doing if it doesn't come as a turn-key non-electrician friendly package.

what's the machine? 4 half horse motors sounds like some kind of deviant woodworking multitasking wonder device.
So in short, you would recommend going for the static converter? bulkiness isn't a problem, the ones in machine mart are approx 25cm cube. It's a coffee roaster smile

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hidetheelephants

11,057 posts

95 months

Saturday 10th September 2011
quotequote all
cqueen said:
So in short, you would recommend going for the static converter? bulkiness isn't a problem, the ones in machine mart are approx 25cm cube. It's a coffee roaster smile
If you don't need to vary the speed of the motors(woodworking machinery, pumps, compressors etc.) then a static or rotary converter will do the job fine. The thing to watch is make sure the unit is big enough, some vendors overstate the rating of their converters.

I have read some anecdotal reports that static converters can result in electric motor 'noise', which probably won't have any detrimental effect on the machine but may be irritating or undesirable in a cafe/retail environment. Anecdotally motors powered from VFDs do not suffer this problem.

Edited by hidetheelephants on Saturday 10th September 15:28

FaineantFreddy

5,407 posts

139 months

Saturday 10th September 2011
quotequote all
Best not to mess around with 3 phase if you don't know what you're doing. I'd be asking myself if I really needed a 3-phase coffee roaster...

hidetheelephants

11,057 posts

95 months

Saturday 10th September 2011
quotequote all
FaineantFreddy said:
Best not to mess around with 3 phase if you don't know what you're doing. I'd be asking myself if I really needed a 3-phase coffee roaster...
Only in the sense that if you aren't competent with single phase 240V then get a sparky to do the fiddly bits; 3 phase at this level is no more dangerous or challenging than domestic wiring.

cqueen

Original Poster:

2,118 posts

122 months

Saturday 10th September 2011
quotequote all
Well it's too late now - I've bought the bloomin thing!

Besides, if it's as easy as just plugging it in and away you go... what could possibly go wrong?!

boxedin

mph1977

10,686 posts

70 months

Saturday 10th September 2011
quotequote all
alternatively swap the 3ph motors for simialr sized and powered single phase ones ...

thinfourth2

32,414 posts

106 months

Sunday 11th September 2011
quotequote all
speak to this guy http://www.drivesdirect.co.uk/Products/Digital_Pha... his knowledge is huge

But i will ask

What roasts the coffee is it gas fired or is there a big electrical heating element you have forgotten about?

And what do the motors do and do they need to be controlled individually?

rolando

712 posts

57 months

Sunday 11th September 2011
quotequote all
This is total and utter bcensoreds:
hidetheelephants said:
3 phase at this level is no more dangerous or challenging than domestic wiring.
...as long as you don't touch anything live.

jason s4

3,706 posts

72 months

Sunday 11th September 2011
quotequote all
hidetheelephants said:
..... 3 phase at this level is no more dangerous or challenging than domestic wiring.
What a totally irresponsible statement considering the OP himself has stated he has no idea what it ispunch

Simpo Two

64,514 posts

167 months

Sunday 11th September 2011
quotequote all
They can both kill you if you touch the wrong wire. So doesn't that make them equally dangerous? Or does 3-phase kill you faster/worse?

CunningPlan

228 posts

62 months

Sunday 11th September 2011
quotequote all
hidetheelephants said:
..... 3 phase at this level is no more dangerous or challenging than domestic wiring.
LOL! Tell you what - we'll attach a croc clip to each of your testicles and then try 230V and 415V and you tell us which hurts more.

cqueen

Original Poster:

2,118 posts

122 months

Sunday 11th September 2011
quotequote all
To be fair - I aint gonna go touching any wires. I'm just gonna plug the thing into a converter and hope it doesn't blow up!

The heating part is done by gas.

roofer

3,683 posts

113 months

Sunday 11th September 2011
quotequote all
CunningPlan said:
LOL! Tell you what - we'll attach a croc clip to each of your testicles and then try 230V and 415V and you tell us which hurts more.
hehe

jason s4

3,706 posts

72 months

Sunday 11th September 2011
quotequote all
cqueen said:
To be fair - I aint gonna go touching any wires. I'm just gonna plug the thing into a converter and hope it doesn't blow up!
TBH, if you bought it second hand, who knows who has been messing about with it in the past.

I would suggest you call a local competent electrician to at least give you some advice first hand.



thinfourth2

32,414 posts

106 months

Sunday 11th September 2011
quotequote all
You will probably find the control system is lowish voltage either 110AC or 24DC

If the motors are control individually I would buy a baby converter for each one and rewire the controls to run off a small transformer

hidetheelephants

11,057 posts

95 months

Sunday 11th September 2011
quotequote all
hidetheelephants said:
FaineantFreddy said:
Best not to mess around with 3 phase if you don't know what you're doing. I'd be asking myself if I really needed a 3-phase coffee roaster...
Only in the sense that if you aren't competent with single phase 240V then get a sparky to do the fiddly bits; 3 phase at this level is no more dangerous or challenging than domestic wiring.
jason s4 said:
What a totally irresponsible statement considering the OP himself has stated he has no idea what it ispunch
CunningPlan said:
LOL! Tell you what - we'll attach a croc clip to each of your testicles and then try 230V and 415V and you tell us which hurts more.
rolleyes
So irresponsible of me to suggest using a sparky? Read the thread; think; type.