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from the Power department...
480 Volts vs. 4160 Volts
Engineering and workplace issues. topic
Posted by Loveland on 18 August, 2003 - 1:29 pm
Hi,

I need help determining when it's best to use 4160V over 480V. For example, in this project I have 3-600hp motors. Two are operational and one spare. I have another 3-150 hp motors and many other smaller motors.

Has anyone done any studies or may just know off the top of their head at what hp level does it pay off to go with 4160V. Taking into account a second transformer would now be required as well as a seperate MCC lineup, etc.

Any help would be appreciated. Thanks!


Posted by Brian McAllister on 19 August, 2003 - 10:39 am
Hello,

480v/4160v??

a few questions come to mind, do you require variable speed?

if, yes- a "Medium Voltage Inverter" will carry a higher cost,and you will have to replace the "existing" motors,more cost added not to mention both will be less readily avaiable from most manufactures in the HP's you mentioned at 4160V.(in the event of a failure)

Whereas a 150-300 or 600HP VFD might come off the shelf, assuming (480V).

Power consumption, and qulaity are of more concern today,then they were in the past this trend is changing and that concern will grow.
Given the recent Black-out, sooner rather than later.

My suggestion is look into an 18-Pulse VFD in the ratings listed, where the total current distortion can guraneted to fall below the IEEE-519 distorion limits.

There by reducing any power factor, or Harmonic issues.

Brian
MCA Sales, Inc.
bmcallister@saftronics.com
www.saftronics.com




Posted by Bob Peterson on 19 August, 2003 - 12:04 pm
I don't know about studies but most specs that deal with such things set an arbitrary maximum HP limit for 460V motors. I have seen this as low as 200 HP.



1 out of 1 members thought this post was helpful...
Posted by Phil Corso on 20 August, 2003 - 12:27 pm
To Loveland:

If you have the transformer capacity at 480V, then that is obviously the way to go. However, if a larger transformer is required, then 4160V is better suited for the 600 hp motors.

If you are interested in alternatives, please provide details of existing facilities!

Regards,
Phil Corso, PE
Boca Raton, FL
[tal-2@webtv.net] (Epsiconinc@aol.com) {pcorso@itt-tech.edu}


Posted by matt hyatt on 9 September, 2003 - 4:08 pm
It really depends on what is already there in terms of power. I have worked in well fields where high voltage transmissions lines were everywhere and they ran 4160 to all the well sites, they dropped in step down transformers only to provide control power at the sites, everything else (motors, VFDs, ect.. were 4160.) I have also seen the flip side, they dropped 480 at well sites then after the vfd, went to a step up transformer to 4160 for the down hole pump. (smaller wire size, lower currents at higher voltages, the pumps were less expensive at the 4160 rating (longer lead time though) and they were smaller in size vs the 480 rating for their applications.) I would not go out of my way to spec 4160 over 480 as the related gear is more expensive (typically, plus you will be dropping in a transformer somewhere) and most standard controls field service technicans are not specifically trained to work with the higher voltage - most draw the line at 480 anyways - besides the voltage issue is usually decided by the engineering firm or company doing the system specifications and design work (say for a large well field or water treatment plant.) Most of my customers would only let licensed electricains work on the high voltage (4160) gear anyways and in the years I spent doing field service work, I never met a field service tech who was a licensed journeyman or master electrical, if fact most did not even have the training to be considered an apprentice or even worked for a shop which had a licensed electrican on board let alone a PE associated with the company.

For the 150 hp motors you mentioned it will be cheaper and faster in the long run to go with 480, everything is pretty much off the shelf, and spares or replacements can be obtained faster - I have seen wells with 4160 pumps down hole off line for months because they were waiting for a 4160 pump motor to become available vs most motors up 400 hp at 480 can be obtained within 6 weeks minimum. Plus try to convince a water district to keep a 600 hp 4160 hp motor on hand just in case, they will be more likely to keep the same size 480 motor on hand vs the former, or if they are in a area prone to lots of lightening stirkes, ask them to keep a 480 to 4160 transformer on hand just in case - considering that it may cost $200K+ to get a well back up after a major failure such as having the pump motor fried by a strike, they will probably just wait and not keep the extra higher voltage gear on hand, it is too expensive to keep that kind of inventory of spares on hand, vs keeping a 480 motor or vfd around.

Matt Hyatt
Technical Consultants
matthewhyatt@msn.com


Posted by otto on 8 July, 2011 - 10:57 am
One has to compare the cost of conductors versus the cost of equipment. 4160V equipment is considerably more expensive than 480V equipment but the necessary conductor size associated with 4160V equipment is almost 1/10 of that required for 480V equipment. The number of motors (no. of conductors) and the location with respect to the stepdown transformers and MCCs (length of conductors) is what determines which system to use, 4160V or 480V.

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