Lathe Electrical Spec's - Electrical - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 05-11-2009, 07:02 AM   #1
Newbie
 
Join Date: May 2009
Posts: 7
Rewards Points: 10
Default

Lathe electrical spec's


I am trying to do a electrical analysis on a machine shop. The lathes in the shop have multiple motors (spindle, oil pump, etc) Each motor has an individual nameplate but I need to know the overall electrical spec's of the machine as a whole( ei total current draw) Can I just simple add all the individual nameplate ratings together of the individual motors or does it depend on how the machines are wired?

Advertisement

matt11111 is offline   Reply With Quote
Old 05-11-2009, 05:59 PM   #2
Tool Geek
 
PaliBob's Avatar
 
Join Date: Jun 2008
Location: Pacific Palisades CA
Posts: 2,543
Rewards Points: 2,066
Default

Lathe electrical spec's


If all you need to know is the total rated current draw on each motor, then you can add the nameplate numbers. That number though will not be the total draw any more than adding up the numbers in your circuit breaker panel will give you a total draw for your panel.
.

Advertisement

__________________
Disclaimer
& Stay Safe
.....Bob Lavery
PaliBob is online now   Reply With Quote
Old 05-12-2009, 06:41 AM   #3
Newbie
 
Join Date: May 2009
Posts: 7
Rewards Points: 10
Default

Lathe electrical spec's


So the rated numbers on the motor are just the absolute maximums? Is there a way to determine exactly how much current is being draw from a machine during general use?
matt11111 is offline   Reply With Quote
Old 05-12-2009, 06:52 AM   #4
Newbie
 
Join Date: May 2009
Posts: 7
Rewards Points: 10
Default

Lathe electrical spec's


Quote:
Originally Posted by PaliBob View Post
If all you need to know is the total rated current draw on each motor, then you can add the nameplate numbers. That number though will not be the total draw any more than adding up the numbers in your circuit breaker panel will give you a total draw for your panel.
.

So the rated numbers on the motor are just the absolute maximums? Is there a way to determine exactly how much current is being draw from a machine during general use?
matt11111 is offline   Reply With Quote
Old 05-12-2009, 09:53 AM   #5
DIYer
 
Join Date: Oct 2008
Location: Virginia
Posts: 910
Rewards Points: 500
Default

Lathe electrical spec's


Nameplate on a motor isn't really absolute maximum, it's closer to a full load maximum. A motor can draw many times nameplate if it's stalled, yet still not enough to trip a breaker before things catch on fire... which is why there are overload protection devices on the motor.
Gigs is offline   Reply With Quote
Old 05-12-2009, 09:57 AM   #6
Newbie
 
Join Date: May 2009
Posts: 7
Rewards Points: 10
Default

Lathe electrical spec's


Quote:
Originally Posted by Gigs View Post
Nameplate on a motor isn't really absolute maximum, it's closer to a full load maximum. A motor can draw many times nameplate if it's stalled, yet still not enough to trip a breaker before things catch on fire... which is why there are overload protection devices on the motor.

Is it correct to say, the RLA specifies what the current draw should be on a motor when operating in optimal conditions? and in reality does a machine actually draw close to the RLA or does it often consume more?
matt11111 is offline   Reply With Quote
Old 05-12-2009, 10:02 AM   #7
DIYer
 
Join Date: Oct 2008
Location: Virginia
Posts: 910
Rewards Points: 500
Default

Lathe electrical spec's


A motor consuming more than its nameplate amps is generally considered overloaded, and probably can't do that in continuous service. There are additional ratings for motors that determine how long they can sustained an overloaded condition in terms of duty cycle (that's called service factor).

If you have to size a circuit based on nameplate amps I think the formula is 125% per NEC.
Gigs is offline   Reply With Quote
Old 05-12-2009, 10:11 AM   #8
My License Ain't 4 Sale..
 
Join Date: Feb 2008
Location: Atlanta, Ga/Hamilton, Al
Posts: 1,813
Rewards Points: 1,000
Default

Lathe electrical spec's


Quote:
Originally Posted by matt11111 View Post
I am trying to do a electrical analysis on a machine shop. The lathes in the shop have multiple motors (spindle, oil pump, etc) Each motor has an individual nameplate but I need to know the overall electrical spec's of the machine as a whole( ei total current draw) Can I just simple add all the individual nameplate ratings together of the individual motors or does it depend on how the machines are wired?
I'm curious. Why are doing "an electrical analysis" on this machine shop?
InPhase277 is offline   Reply With Quote
Old 05-12-2009, 10:14 AM   #9
Newbie
 
Join Date: May 2009
Posts: 7
Rewards Points: 10
Default

Lathe electrical spec's


Quote:
Originally Posted by InPhase277 View Post
I'm curious. Why are doing "an electrical analysis" on this machine shop?

asigned task for work term
matt11111 is offline   Reply With Quote
Old 05-12-2009, 12:12 PM   #10
Member
 
Join Date: Jun 2007
Posts: 3,510
Rewards Points: 2,008
Default

Lathe electrical spec's


Take a good look at the lathes themselves. Every lathe I have ever worked on (plenty) had a nameplate for the lathe itself. This nameplate is used to determine wire size and breaker size. You CANNOT use individual motor nameplates. Motor nameplate designations are usually the maximum. You need the average.
J. V. is offline   Reply With Quote
Old 05-12-2009, 01:26 PM   #11
Newbie
 
Join Date: May 2009
Posts: 7
Rewards Points: 10
Default

Lathe electrical spec's


Quote:
Originally Posted by J. V. View Post
Take a good look at the lathes themselves. Every lathe I have ever worked on (plenty) had a nameplate for the lathe itself. This nameplate is used to determine wire size and breaker size. You CANNOT use individual motor nameplates. Motor nameplate designations are usually the maximum. You need the average.

I have looked at the lathes in the shop many times and only a few have what looks like an overall nameplate. Most of them though only have individual nameplates on each motor.
What I'm looking for is some sort of measurment of the daily power consumption by the machine. For example if it is energized for X period of time how much power/current will be consumed. From what I've read online the nameplate information states the current draw at rated load. So it would be the current draw if the rated voltage,freq,and PF were present. Is this correct?
matt11111 is offline   Reply With Quote
Old 05-13-2009, 10:19 PM   #12
Newbie
 
Join Date: Mar 2009
Posts: 16
Rewards Points: 10
Default

Lathe electrical spec's


Name plates are worthless for you.

Breaker sizes are worthless.

motor sizes are worthless.

OK, here is the answer, I've done this.

Buy a set of data loggers....like the hobo units.....couple hundred bucks.

Hook them up to the incoming power feed

Let the collect data for a few hours, days or weeks. Then download the data to a pc.

they will give the amp draw (max, min average whatever you want) then you can calculate the power usage.

If you are too poor or cheap to buy the data loggers then get an amp clamp and test the incoming power while the lathe is running, not as good as a datalogger but better than totally making stuff up (or believing nameplates).

And...tell the company if they are looking for energy savings (as almost all do) they need to worry more about the lighting and compressors not the value added work.
mattman is offline   Reply With Quote
Old 05-13-2009, 11:59 PM   #13
DIYer
 
Join Date: Oct 2008
Location: Virginia
Posts: 910
Rewards Points: 500
Default

Lathe electrical spec's


People do underestimate how inefficient compressed air is.

Replacing all the compressed air tools with electrical tools might double your electrical efficiency in some cases.
Gigs is offline   Reply With Quote
Old 05-14-2009, 07:43 AM   #14
Newbie
 
Join Date: Mar 2009
Posts: 16
Rewards Points: 10
Default

Lathe electrical spec's


An air motor is 8 times less effeicient than an electric motor.

People have just come think of compressed air as free.
mattman is offline   Reply With Quote
Old 05-14-2009, 08:48 AM   #15
Newbie
 
Join Date: May 2009
Posts: 7
Rewards Points: 10
Default

Lathe electrical spec's


Quote:
Originally Posted by mattman View Post
Name plates are worthless for you.

Breaker sizes are worthless.

motor sizes are worthless.

OK, here is the answer, I've done this.

Buy a set of data loggers....like the hobo units.....couple hundred bucks.

Hook them up to the incoming power feed

Let the collect data for a few hours, days or weeks. Then download the data to a pc.

they will give the amp draw (max, min average whatever you want) then you can calculate the power usage.

If you are too poor or cheap to buy the data loggers then get an amp clamp and test the incoming power while the lathe is running, not as good as a datalogger but better than totally making stuff up (or believing nameplates).

And...tell the company if they are looking for energy savings (as almost all do) they need to worry more about the lighting and compressors not the value added work.

Can amp clamps measure the current on a 3 phase system and can they tell me the phase angle of the current?

Advertisement

matt11111 is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Just for fun Andy in ATL Electrical 56 10-20-2009 10:33 AM
Electrical Engineer allowed to do Electrical work? SarahJennifer Electrical 48 09-21-2009 09:15 PM
Usefull Electrical Web Sites PaliBob Electrical 1 02-03-2009 11:49 AM
Electrical Box near Shower Valve dasajame Electrical 3 07-07-2008 07:46 AM
2 Prong Electrical mjcongleton Electrical 10 04-16-2008 09:59 AM




Top of Page | View New Posts