Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

3-Phase Back-of-the-envelope Calculation Check

Status
Not open for further replies.

dksoba

Member level 2
Joined
May 5, 2010
Messages
47
Helped
3
Reputation
6
Reaction score
0
Trophy points
1,286
Activity points
1,743
Hi All,

My small consulting company is moving into an industrial location since we are getting a used CNC milling machine. The machine takes 208V 3-Phase power, and the required current rating is 40 amps. I know that actual current usage depends on the load, but I'm trying to estimate the worst case scenario for the power usage of the machine.

My calculation is as follows:

P = IV
P = (40A worst case)*(3 since it's 3-phase)*(208V RMS) = 24.96 kilowatt's

The power company charges $0.15 for each killowatt hour, so for each hour the maximum power cost of the machine is estimated as:

Cost = (24.96 killowatt)*($0.15/(kw*hour)) = $3.744/hour (About a cup of Starbucks coffee, I'm told)

So if I run the machine for 40 hours a week, for a month (which I won't), it would cost: (40 hours/week)*(4 week/month)*($3.744/hour) = $600/month. I can live with that. I just don't want to end up with a $10,000 electric bill as a surprise one month. In reality, I'll run the machine 2 hours a day, at 10% load, so it's probably more like (10 hours/week)*(4 week/month)*($0.3744/hour due to 10% load) = $14.976/month.

Thanks everyone for double checking my 3-phase back-of-the-envelope calculations.

Matt
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top