3 phase power

[Jim_gsxr1000]

all my workshop equipment works of 230V iv no intention of getting 415v just wondered what the differnce is between a 4 pin red plug and a 5 pin red plug like, why is there an extra pin ?

Any of the sparky types out there be able to shed light on this spanner monkeys curiosity ?

 

[the snooper]

the 5th pin is negative

4 pin plugs are 3 live 1 earth

 

[Jim_gsxr1000]

do they use a neutral ?

 

[the snooper]

some three phase machines use a negative if it needs 240 volts for some circuits for instance maybe a control circuit others may use a transformer to do it

with a negative you can then get 240v from any of the three phases

 

[Jim_gsxr1000]

i see another quick question, see if i used say for a round figure 10Kwh of electricity, would it cost the same if it was used via single phase or 3 phase? like would 3 phase be 3 lots of 10Kwh ?

 

[the snooper]

10 kw is 10 kw only on 3 phase it would 3,333.3 watts per phase/ meter

 

[Jim_gsxr1000]

i see so once instaled the cost of electricity/bill wouldent go up ?

 

[brightspark]

i see so once instaled the cost of electricity/bill wouldent go up ?

just the rental price for there 3 phase meter slightly

 

[the snooper]

i think some three phase gear can be more efficient then simple 240 but not 100% sure about that

 

[the snooper]

just the rental price for there 3 phase meter slightly

yeah forgot about the 3 standing charges

 

[Jim_gsxr1000]

Cheers, just thought id ask, i got a quote about 2 years ago from scottish power for $15 volts, they quoted £7200 to get 3 phases in, at that point i just gave up and bopught everything in 230

 

[the snooper]

its rediculous what they quote, the cables are in the street anyway, just find out which of your neighbours are on different phases and plug in an extension lead

 

[Robotstar5]

just find out which of your neighbours are on different phases and plug in an extension lead

Just remember to mark the leads brown, black & grey, you can't use red, yellow & blue anymore

 

[brightspark]

Just remember to mark the leads brown, black & grey, you can't use red, yellow & blue anymore

and dont forget the neutral which is blue if its 4 core and the black is now a live

 

[julianthegypsy]

Many machines run three phase because the motors are much smoother. I have a beautiful old tapping machine which is 1/4 hp but runs on three phase!

 

[Exuptoy]

Many machines run three phase because the motors are much smoother. I have a beautiful old tapping machine which is 1/4 hp but runs on three phase!

That's rubbish!
The reason they sell 3 phase is for the same power and torque there is a limit in the size you could supply with single phase, also you'd not get a supply large enough from the substation. 1ph motors have to have capacitors fitted to give the phase angle lag to allow the motor to start where as 3ph are 120 degrees out per phase which give the shunt to spin. That's why when you lose a fuse in 3ph the motor will stall.
Also when 3ph are controlled you can wire them via the starter to run up in star connected formation and they switch over to delta connected when the start load is reduced enough. Also start current can by multiplied by 6 times so your 2kw motor would need 50a to start but only 8a to run. Everything would need to be beefed up.

For your tapping machine that small you could use a small 3ph inverter. You can get a 3kw one now for relatively little money.

http://www.ebay.co.uk/sch/i.html?_trksid=p4069.m570.l1313&_nkw=1/4+hp+inverter&_sacat=0&_from=R40

 

[brewdexta]

the 5th pin is negative

4 pin plugs are 3 live 1 earth

Pedantry corner here! its Neutral. Negative leads are used on DC not AC.

I guess your half right, its negative, then its positive, then its negative.....

Sorry - I shall go back to telling grandfathers how to suck eggs

 

[Exuptoy]

Pedantry corner here! its Neutral.

: I know I had to bite my tongue.

 

[the snooper]

Pedantry corner here! its Neutral. Negative leads are used on DC not AC.

I guess your half right, its negative, then its positive, then its negative.....

Sorry - I shall go back to telling grandfathers how to suck eggs

go stand in the corner