Motor 1hp wiring

jodysutts

Hi all, hope you can help!
I had to upgrade the motor on my lathe as i simply didn't have enough power. the motor I burnt out was a 1/2hp and the one i am putting in is 1hp.
the new 1hp motor is 200/220V A.C. 8amp 2900rpm from a circular saw.

The motor has a power lead with a blue circular plug on the end. (like the 110v yellow circular plug)
I don't have a socket for this plug in my workshop so can I just wire a cable from the normal household socket to a circular socket to suit the motor plug?
I also need to get a new switch so i can turn it on/off at the lathe. what type of switch do I need to buy to suit the motor? and what is the best way to wire the whole thing up?

Sorry to ask so much! Thanks in advance.

DublinDilbert

Yep in theory you can cut off the blue plug and fit a 13amp plug. The problem might be the the start up current for the motor and the 13A fuse. The smaller of the 'blue' plugs is ratted for 16A.

Is the new motor 8amps average? About 2kw??

M cebee

prob a manual starter w/overload for the lathe anyhow

do those power tools generally have any overload protection at all-or do they just go up in smoke?

Bruthal

A 1HP motor should be around 750 watts or 3 amps. The starting current will be around 18 amps or so but for a very short time, so a 13 amp plugtop fuse should be ok. Im not sure how it would be an 8 amp draw on it, this would be near 3hp motor i thought. Maybe its 0.4 or 0.5 pf as well which would be 7 or 8 amps for a 1hp motor alright

But on a lathe a start stop DOL starter is important, not only for the overload protection for the motor, but as a safety because it can and should have emergency stops which will require pressing of the start button again for the motor to start again after the stops are reset, or in the event of power cut, the motor will not re-start when the power returns except when the start button is pressed again. So a 16 or 20 amp circuit with DOL starter would be the best there.

I suppose if its just a lathe in a home workshop it could just be a plug in job. I just think these type of machines should have a Start/Stop setup.

M cebee

i was thinking of those

http://www.mcg-products.com/pages/page11.html
didn't realise 'undervoltage release' is separate

Bruthal

Im not sure myself if the lathe would have the starter in it, it certainly wont operate that way if the motor is plugged in just through a switch. I have a small pillar drill here and it has a start stop inbuilt. I would`t like the idea of just an on/off switch on any of them motorised machines.

And it needs the starter to have the overloads like you mentioned to work.

A contactor, start and stop buttons and overload and they handy enough to make up.

Undervoltage release is probably not needed on that, if it goes too low the contactor will drop out, if not so low the overload should trip,

M cebee

the manual starter is just a manual switch with an overload -undervoltage(no-volt) release is separate

the dol starter won't need it -to prevent restarting

Bruthal

M cebee wrote: »

the manual starter is just a manual switch with an overload -undervoltage(no-volt) release is separate

the dol starter won't need it -to prevent restarting

True yes, anyway a DOL starter is straight forward to make up cheap enough and the ideal setup for this lathe.

2011

Hi all, hope you can help!
I had to upgrade the motor on my lathe as i simply didn't have enough power. the motor I burnt out was a 1/2hp and the one i am putting in is 1hp.
the new 1hp motor is 200/220V A.C. 8amp 2900rpm from a circular saw.

1 hp = about 745 watts
745 output = at about 90% efficiency = about 820 watts input
At a power factor of about 0.9 the full load current will be about 4 amps (a 230VAC)

The motor has a power lead with a blue circular plug on the end. (like the 110v yellow circular plug)

These are known as the "commando type" and are designed to take up to 16A. They are better suited to a workshop environment as they are more robust that the 13A type and they have an IP rating.

I don't have a socket for this plug in my workshop so can I just wire a cable from the normal household socket to a circular socket to suit the motor plug?

I would rather have a dedicated circuit for the lathe without any plug socket arrangement at all. This would have a local isolator and contractor with suitable overload protection.

I also need to get a new switch so i can turn it on/off at the lathe. what type of switch do I need to buy to suit the motor? and what is the best way to wire the whole thing up?

IMHO a stop/start station and a local emergency stop button would be the way to go. Lathes can be dangerous as I am sure you know! I is always nice to have a strategically placed emergency stop button (or 2). It might just save your life, rotating machinery can be dangerous even to skilled professionals.

Sorry to ask so much! Thanks in advance.

No problem, that is what the forum is for!

Bruthal

2011 wrote: »

1 hp = about 745 watts
745 output = at about 90% efficiency = about 820 watts input
At a power factor of about 0.9 the full load current will be about 4 amps (a 230VAC)

I would rather have a dedicated circuit for the lathe without any plug socket arrangement at all. This would have a local isolator and contractor with suitable overload protection.


IMHO a stop/start station and a local emergency stop button would be the way to go. Lathes can be dangerous as I am sure you know! I is always nice to have a strategically placed emergency stop button (or 2). It might just save your life, rotating machinery can be dangerous even to skilled professionals.

I thought i mentiond some of that:)

2011

I thought i mentiond some of that

You did mention some of it.

I added a bit too

M cebee

2011 wrote: »

1 hp = about 745 watts
745 output = at about 90% efficiency = about 820 watts input
At a power factor of about 0.9 the full load current will be about 4 amps (a 230VAC)


These are known as the "commando type" and are designed to take up to 16A. They are better suited to a workshop environment as they are more robust that the 13A type and they have an IP rating.


I would rather have a dedicated circuit for the lathe without any plug socket arrangement at all. This would have a local isolator and contractor with suitable overload protection.


IMHO a stop/start station and a local emergency stop button would be the way to go. Lathes can be dangerous as I am sure you know! I is always nice to have a strategically placed emergency stop button (or 2). It might just save your life, rotating machinery can be dangerous even to skilled professionals.


No problem, that is what the forum is for!

looked at one recently -the FLA is prob 8amps alright-efficiency is prob much lower than 90%
http://www.elec-toolbox.com/usefulinfo/flamtrcharts.htm

the only way of gettting accurate FLA is the nameplate

Bruthal

All single phase induction motors are innefficient, thats why you wont see many above 3 or 4 HP. They are probably a little more efficient as the number of pairs of poles increase, but this one the OP was asking about is only a single pair of poles of the rpm is 2900. So it probbably is 60 or 70 percent efficient with a 0.8 pf or something along them lines.

2011

Yes I agree 0.9 pf and 90% efficiency might be a bit optomistic! To be honest I was doing the calculation with ball park numbers to see of it could be fed from a 13A plug. I then thought better of it and decided that this was not the best way to go.

Bruthal

2011 wrote: »

Yes I agree 0.9 pf and 90% efficiency might be a bit optomistic! To be honest I was doing the calculation with ball park numbers to see of it could be fed from a 13A plug. I then thought better of it and decided that this was not the best way to go.

Yea its ball park figures we are all on in these situations, It probably would hold on a 13amp fuse for a few starts but its own circuit is best with a 16 amp blue plug, think i had said a 16 or 20 amp circuit is best in earlier post, i forget now but it probably would not run near its full load in a lathe, but that wont change the starting current peak anyway, a motor starting fully loaded will just pull this peak current for longer. The starting current of a motor is the same current the motor would pull if held stopped, or slightly higher as the winding itself has no back emf at the instant of energising as well as the rotor being stopped.

A lathe motor will have no real load while starting apart from the weight of the chuck so its peak starting current will be for a tiny fraction of a second probably. But the DOL is definitely the way to go, with 2 or 3 emergency stops.

jodysutts

thank you to everyone for answering my questions i have it all up and running now safe and reliable!

2011 & robbie you rock!!

cheers!