Electrical power requirement question - RC Groups
Feb 24, 2012, 05:13 PM
Emimec
Emimec
Guest

Electrical power requirement question

Considering getting a VMC but need to check I have the power to run it. As
I'm no electrician, I am trying to understand what the text I pasted below
means

electrics - voltage/frequency 380 / 50 V/Hz
main drive DC 20 kW
spindle drive 15 kW

How many Horses ? How many amps supply do I need ?

My now scrapped Auto lathe had a big beast of a motor on it, the plate says
5.5/5.5/3,?? forgot the last bit. I think it was a 7.5 horse 2 speed motor,
but I cant seem to grasp the KW - horsepower confidently. I also understand
this is spread across 3 phases ?
Bob
Feb 24, 2012, 05:57 PM
Tony Jeffree
Tony Jeffree
Guest

Re: Electrical power requirement question

On Fri, 24 Feb 2012 22:13:55 -0000, "Emimec"
<emimec.19@NOSPAMbtinternet.com> wrote:

>Considering getting a VMC but need to check I have the power to run it. As
>I'm no electrician, I am trying to understand what the text I pasted below
>means
>
> electrics - voltage/frequency 380 / 50 V/Hz
> main drive DC 20 kW
> spindle drive 15 kW
>
>
>How many Horses ? How many amps supply do I need ?
>
>My now scrapped Auto lathe had a big beast of a motor on it, the plate says
>5.5/5.5/3,?? forgot the last bit. I think it was a 7.5 horse 2 speed motor,
>but I cant seem to grasp the KW - horsepower confidently. I also understand
>this is spread across 3 phases ?
>Bob
>

1 HP is approx 3/4 of a KW. So your 20KW is about 26 horses...and
would be a major space-heater. I suspect you have lost a decimal point
somewhere.

Regards,
Tony
Feb 25, 2012, 02:41 AM
Emimec
Emimec
Guest

Re: Electrical power requirement question

"Tony Jeffree" <tony@jeffree.co.uk> wrote in message
news:qa5gk7l3aqdsv0aca2obub8cc83a9jvp08@4ax.com...

> On Fri, 24 Feb 2012 22:13:55 -0000, "Emimec"
> <emimec.19@NOSPAMbtinternet.com> wrote:
>

>>Considering getting a VMC but need to check I have the power to run it. As
>>I'm no electrician, I am trying to understand what the text I pasted below
>>means
>>
>> electrics - voltage/frequency 380 / 50 V/Hz
>> main drive DC 20 kW
>> spindle drive 15 kW
>>
>>
>>How many Horses ? How many amps supply do I need ?
>>
>>My now scrapped Auto lathe had a big beast of a motor on it, the plate
>>says
>>5.5/5.5/3,?? forgot the last bit. I think it was a 7.5 horse 2 speed
>>motor,
>>but I cant seem to grasp the KW - horsepower confidently. I also
>>understand
>>this is spread across 3 phases ?
>>Bob
>>

> 1 HP is approx 3/4 of a KW. So your 20KW is about 26 horses...and
> would be a major space-heater. I suspect you have lost a decimal point
> somewhere.
>
> Regards,
> Tony

Thanks
I pasted the info as supplied from the seller. Must admit, sounded a lot to
me as well !!
The "DC" bit worries me. I think I'll have to get the info again from him
and hope there is a mistake in the original.
In the meantime, maybe someone on here has Bridgeport 460 or similar and
they could suggest what the power for that is ?
Bob
Feb 25, 2012, 03:28 AM
Andrew Mawson
Andrew Mawson
Guest

Re: Electrical power requirement question

"Emimec" wrote in message news:gf2dneh4-LMJDdXSnZ2dnUVZ8gidnZ2d@bt.com...

>
>
>"Tony Jeffree" <tony@jeffree.co.uk> wrote in message
>news:qa5gk7l3aqdsv0aca2obub8cc83a9jvp08@4ax.com.. .

>> On Fri, 24 Feb 2012 22:13:55 -0000, "Emimec"
>> <emimec.19@NOSPAMbtinternet.com> wrote:
>>

>>>Considering getting a VMC but need to check I have the power to run it.
>>>As
>>>I'm no electrician, I am trying to understand what the text I pasted
>>>below
>>>means
>>>
>>> electrics - voltage/frequency 380 / 50 V/Hz
>>> main drive DC 20 kW
>>> spindle drive 15 kW
>>>
>>>
>>>How many Horses ? How many amps supply do I need ?
>>>
>>>My now scrapped Auto lathe had a big beast of a motor on it, the plate
>>>says
>>>5.5/5.5/3,?? forgot the last bit. I think it was a 7.5 horse 2 speed
>>>motor,
>>>but I cant seem to grasp the KW - horsepower confidently. I also
>>>understand
>>>this is spread across 3 phases ?
>>>Bob
>>>

>> 1 HP is approx 3/4 of a KW. So your 20KW is about 26 horses...and
>> would be a major space-heater. I suspect you have lost a decimal point
>> somewhere.
>>
>> Regards,
>> Tony

>
>Thanks
>I pasted the info as supplied from the seller. Must admit, sounded a lot to
>me as well !!
>The "DC" bit worries me. I think I'll have to get the info again from him
>and hope there is a mistake in the original.
>In the meantime, maybe someone on here has Bridgeport 460 or similar and
>they could suggest what the power for that is ?
>Bob

The DC will undoubtedly be internally generated within the machine control,
and is quoted as a description of the type of drive, however it still is
power that you have to supply. What you need is what the rating plate on the
machine quotes as AC power input.

This post quotes the spindle as 2.2 kw:

http://www.cnczone.com/forums/produc...420_4axis.html

Regards,

AWEM
Feb 25, 2012, 04:56 AM
news.plus.net
news.plus.net
Guest

Re: Electrical power requirement question

On 24/02/2012 22:13, Emimec wrote:

> Considering getting a VMC but need to check I have the power to run it. As
> I'm no electrician, I am trying to understand what the text I pasted below
> means
>
> electrics - voltage/frequency 380 / 50 V/Hz
> main drive DC 20 kW
> spindle drive 15 kW
>
>
> How many Horses ? How many amps supply do I need ?
>
> My now scrapped Auto lathe had a big beast of a motor on it, the plate says
> 5.5/5.5/3,?? forgot the last bit. I think it was a 7.5 horse 2 speed motor,
> but I cant seem to grasp the KW - horsepower confidently. I also understand
> this is spread across 3 phases ?
> Bob
>
>

Power is 746W/horsepower, plus about 15% losses to be sure. Sounds like
some exotic motor with a plate like that. Is it a normal induction motor?

Rob.
Feb 25, 2012, 04:58 AM
news.plus.net
news.plus.net
Guest

Re: Electrical power requirement question

On 25/02/2012 09:56, news.plus.net wrote:

> On 24/02/2012 22:13, Emimec wrote:

>> Considering getting a VMC but need to check I have the power to run
>> it. As
>> I'm no electrician, I am trying to understand what the text I pasted
>> below
>> means
>>
>> electrics - voltage/frequency 380 / 50 V/Hz
>> main drive DC 20 kW
>> spindle drive 15 kW
>>
>>
>> How many Horses ? How many amps supply do I need ?
>>
>> My now scrapped Auto lathe had a big beast of a motor on it, the plate
>> says
>> 5.5/5.5/3,?? forgot the last bit. I think it was a 7.5 horse 2 speed
>> motor,
>> but I cant seem to grasp the KW - horsepower confidently. I also
>> understand
>> this is spread across 3 phases ?
>> Bob
>>
>>

> Power is 746W/horsepower, plus about 15% losses to be sure. Sounds like
> some exotic motor with a plate like that. Is it a normal induction motor?
>
> Rob.

Sorry did auto pilot response.....embarrassing.

Rob.
Feb 26, 2012, 08:57 AM
Uffe Bærentsen
Uffe Bærentsen
Guest

Re: Electrical power requirement question

Den 25-02-2012 10:56, news.plus.net skrev:

> Power is 746W/horsepower, plus about 15% losses to be sure. Sounds like
> some exotic motor with a plate like that. Is it a normal induction motor?

I whished that was the whole truth.
In USA it is correct but where I live (Denmark) it is not.
Here it is 736W/horsepower.
Not a great difference but enough to add some confusion.
AFIK the 736 goes for Europe and the 746 goes for USA and whatever more
countries, I do not know.

--
Uffe Bærentsen
Feb 26, 2012, 09:58 AM
David Billington
David Billington
Guest

Re: Electrical power requirement question

Uffe Bærentsen wrote:

> Den 25-02-2012 10:56, news.plus.net skrev:
>

>> Power is 746W/horsepower, plus about 15% losses to be sure. Sounds like
>> some exotic motor with a plate like that. Is it a normal induction
>> motor?

>
> I whished that was the whole truth.
> In USA it is correct but where I live (Denmark) it is not.
> Here it is 736W/horsepower.
> Not a great difference but enough to add some confusion.
> AFIK the 736 goes for Europe and the 746 goes for USA and whatever
> more countries, I do not know.
>
>
>

Actually what you're referring to would correctly be Pferdestarke,
abbreviated PS, and often referred to as metric horsepower. Car ads in
the UK usually have it mentioned in the small print somewhere indicating
the figures are PS rather than hp but for most purposes the 1.3%
difference doesn't matter and in kW we should all know that's
unambiguous and can convert to whatever else we like. /

/
Feb 26, 2012, 11:33 AM
David Littlewood
David Littlewood
Guest

Re: Electrical power requirement question

Bærentsen <leiti_FJERNES_@hotmail.com> writes

>Den 25-02-2012 10:56, news.plus.net skrev:
>

>> Power is 746W/horsepower, plus about 15% losses to be sure. Sounds like
>> some exotic motor with a plate like that. Is it a normal induction motor?

>
>I whished that was the whole truth.
>In USA it is correct but where I live (Denmark) it is not.
>Here it is 736W/horsepower.
>Not a great difference but enough to add some confusion.
>AFIK the 736 goes for Europe and the 746 goes for USA and whatever more
>countries, I do not know.
>

Interesting. According to the Oxford Dictionary of Weights and measures,
the term horsepower was coined by James Watt as part of the marketing of
his steam engines. Its value in the UK settled down to be defined as 550
ft.lb.s^-1, which converts to 745.699872 W. Continental Europe seems to
have decided on a metric version, defined as 75 kgf.m.s^-1, which is
735.499 W. The USA seems to dislike untidy numbers, so they appear to
define it as 746 W, though I can't find definitive proof of this.

Since the UK invented the term, I claim we should take priority, though
I'm quite happy to use 746 W in everyday use :-)

David
--
David Littlewood
Feb 26, 2012, 01:49 PM
Andrew Mawson
Andrew Mawson
Guest

Re: Electrical power requirement question

"David Littlewood" wrote in message
news:b9P1VLBA7lSPFwmg@dlittlewood.co.uk...

>
><leiti_FJERNES_@hotmail.com> writes

>>Den 25-02-2012 10:56, news.plus.net skrev:
>>

>>> Power is 746W/horsepower, plus about 15% losses to be sure. Sounds like
>>> some exotic motor with a plate like that. Is it a normal induction
>>> motor?

>>
>>I whished that was the whole truth.
>>In USA it is correct but where I live (Denmark) it is not.
>>Here it is 736W/horsepower.
>>Not a great difference but enough to add some confusion.
>>AFIK the 736 goes for Europe and the 746 goes for USA and whatever more
>>countries, I do not know.
>>

>Interesting. According to the Oxford Dictionary of Weights and measures,
>the term horsepower was coined by James Watt as part of the marketing of
>his steam engines. Its value in the UK settled down to be defined as 550
>ft.lb.s^-1, which converts to 745.699872 W. Continental Europe seems to
>have decided on a metric version, defined as 75 kgf.m.s^-1, which is
>735.499 W. The USA seems to dislike untidy numbers, so they appear to
>define it as 746 W, though I can't find definitive proof of this.
>
>Since the UK invented the term, I claim we should take priority, though I'm
>quite happy to use 746 W in everyday use :-)
>
>David

Well it rather depends if you're talking Clydesdales weighing in at a tad
short of a ton, or a New Forest Pony. I've had a Clydesdale step on my foot
so I know they're genuine heavy horses worthy of generating a one horsepower
grunt, whereas the New Forest Pony is regarded by the French as suitable for
a mid day snack!

AWEM
Feb 27, 2012, 02:14 AM
Emimec
Emimec
Guest

Re: Electrical power requirement question

"Andrew Mawson" <andrew@please_remove_me.mawson.org.uk> wrote in message
news:UImdnTm06pICBtXSnZ2dnUVZ8judnZ2d@bt.com...

> "Emimec" wrote in message news:gf2dneh4-LMJDdXSnZ2dnUVZ8gidnZ2d@bt.com...

>>
>>
>>"Tony Jeffree" <tony@jeffree.co.uk> wrote in message
>>news:qa5gk7l3aqdsv0aca2obub8cc83a9jvp08@4ax.com. ..

>>> On Fri, 24 Feb 2012 22:13:55 -0000, "Emimec"
>>> <emimec.19@NOSPAMbtinternet.com> wrote:
>>>
>>>>Considering getting a VMC but need to check I have the power to run it.
>>>>As
>>>>I'm no electrician, I am trying to understand what the text I pasted
>>>>below
>>>>means
>>>>
>>>> electrics - voltage/frequency 380 / 50 V/Hz
>>>> main drive DC 20 kW
>>>> spindle drive 15 kW
>>>>
>>>>
>>>>How many Horses ? How many amps supply do I need ?
>>>>
>>>>My now scrapped Auto lathe had a big beast of a motor on it, the plate
>>>>says
>>>>5.5/5.5/3,?? forgot the last bit. I think it was a 7.5 horse 2 speed
>>>>motor,
>>>>but I cant seem to grasp the KW - horsepower confidently. I also
>>>>understand
>>>>this is spread across 3 phases ?
>>>>Bob
>>>>
>>> 1 HP is approx 3/4 of a KW. So your 20KW is about 26 horses...and
>>> would be a major space-heater. I suspect you have lost a decimal point
>>> somewhere.
>>>
>>> Regards,
>>> Tony

>>
>>Thanks
>>I pasted the info as supplied from the seller. Must admit, sounded a lot
>>to me as well !!
>>The "DC" bit worries me. I think I'll have to get the info again from him
>>and hope there is a mistake in the original.
>>In the meantime, maybe someone on here has Bridgeport 460 or similar and
>>they could suggest what the power for that is ?
>>Bob

>
> The DC will undoubtedly be internally generated within the machine
> control, and is quoted as a description of the type of drive, however it
> still is power that you have to supply. What you need is what the rating
> plate on the machine quotes as AC power input.
>
> This post quotes the spindle as 2.2 kw:
>
> http://www.cnczone.com/forums/produc...420_4axis.html
>
> Regards,
>
> AWEM

Many thanks all
Seems the most reliable way is once again to see for myself, and follow
advice given here, and get the info from the machine maunufactures plate. I
did request this from the seller, but he seems to be confused along the line
somewhere.

To answer one question about the motor I mentioned that was 5.5/5.5/3 XX It
is a Brook Crompton 2 speed beastie, powered my now scrapped, 2 inch
capacity EMI-MEC auto lathe, but is still sitting on the floor, as its very
heavy, and cant decide if its to be sold or go to the scrappy
Bob>