50 Hz. vs. 60 Hz.

[melliott]

Just looking for some information. Our company is starting a business in China and they are looking to me to give them load calculation for the equipment they are purchasing. I know that their voltages are 390/220 50Hz. Can I use the same load calculations 50 Hz. as I do for 60?

 

[davidbeach]

Load is load. You should do a search of this forum for 50Hz 60Hz, there have been many discussions about equipment ratings and operations when changing frequency.

 

[jraef]

Davidbeach is right, although I think that in light of the vagueness of your question, it would be more accurate to say that power is power, or more spcifically kW is kW.

IF you wre speaking of "load" as being current, then the difference in voltage (not frequency) would mean that busbars, cables etc. would need to be bigger because the CURRENT load would be higher if the kW was the same.

IF you were speaking of "load" as being total work performed over time, then in some applications the difference in speed from 60Hz to 50Hz combined with the voltage being lower may require slightly larger motors to accomplish the same net output in the same amount of time as it would at 480V 60Hz (assuming that is what you meant, you never said that either).

JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
For the best use of Eng-Tips, please click here -> faq731-376

 

[davidbeach]

Good points jraef. I was thinking of the mechanics of making a load calculation. All the numbers will be different, but how the numbers are manipulated doesn't change.

 

[jraef]

That's probably what he meant too, I was just being persnikety about how the question was asked. Had a long day and night troubleshooting in a cold jobsite yesterday because of a stupid component failure, so I'm a little cranky today...

melliot,
Sorry if it sounded like I was taking it out on you!

JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
For the best use of Eng-Tips, please click here -> faq731-376

 

[itsmoked]

From a motor's perspective: faq237-1224

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[jraef]

Shameless self promotoin .

Just kidding of course Keith, you did a great job on that FAQ and did it for this exact reason. I recently pointed someone in a different forum to it because it sums up some complex issues into one page, saving me from typing it over and over again.

JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
For the best use of Eng-Tips, please click here -> faq731-376

 

[itsmoked]

Well I can't take all the credit as I learned a lot of it from people here. Also melliott's question wasn't precisely related but I thought he could benefit.

BTW jraef, dang cold around here isn't it! Went out with a non-contact thermometer this morning at 0400 and found 21F on the covered porch and 11F in the open. 9F on top horizontal ivy. burrrr.. But the new furnace is tops!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[jraef]

I spent most of my day yesterday at my job-site-from-hell in El Dorado Hills because the Ailing Badly PLC took a dump on me again (2nd CPU card to go haywire in a month). It never got above 50 at the plant site in the hills, but when the sun went down last night the temperature dropped as fast as the light level. By the time I finished at 7:30PM it was 20 degrees.

For those of you reading this in cold climes this may not seem to be a big deal, but Keith and I are California boys, we are NOT used to this!

JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
For the best use of Eng-Tips, please click here -> faq731-376