Soft Motor Starts on Pumps [RE-wrenches]

Mon Mar 6 04:17:05 PST 2006

Hello Jeff,

Are you sure that soft start will help reduce the demand charges?  My
experience is that that the demand charges are based on the highest 15
minute load of the month, not the highest few seconds of the month.  Of
course it can be a more complex than that but in essence that is accurate.

If that is the case soft start won't reduce your 3-phase customers peak
charges so I'd check into that before I went much further.

Best,

Travis Creswell
Ozark Energy Services

-----Original Message-----
From: Jeff Clearwater [mailto:clrwater at earthlink.net] 
Sent: Sunday, March 05, 2006 1:25 AM
To: RE-wrenches at topica.com
Subject: Soft Motor Starts on Pumps [RE-wrenches]

Hello All,

I know that large industrial motors benefit greatly from soft-start 
motor controls.  What I don't know is how small soft start controls 
can go and still be economically practical - or what is available for 
single phase.

I have a couple of customers - on grid - with large submersible well 
pumps - one is 60 HP (3 phase hi-leg delta 240 VAC).  They are paying 
alot on peak charges.  Anyone know of a good supplier of motor 
controls for that pump?  Are the economics worth it at this size?  I 
also know that some smart motor controls not only eliminate peak 
charges but also do power tracking and find the efficiency sweet 
spots.  Is this significant on a submersible well pump motor?

I also have a few off-grid customers with 5 HP deep well pumps 
pushing water up 500' (plus another 100+ for the pressure tank).  I'm 
working on them to go DC positive displacement to a non-pressurized 
tank and small booster pump (PD again), but in the meantime, is there 
anything I can do with soft motor controls so we don't hammer the 
inverter (or in one case not need to buy such big inverters until we 
can get their water system to be an off-grid one)?  I measured 67 
Amps In Rush on this 5 HP pump (240VAC) with a run amperage of 22..

Do smart motor controls - especially the ones regulating phase angle 
- inherently problematic on off-grid inverters?  Might there be 
compatibility issues?

Appreciate any help you can offer on this.  Especially suppliers with 
good tech support!

Thanks!

Jeff C.
-- 
~~~~~~~~~~~~~
Jeff Clearwater
Village Power Design Associates
Sustainable Energy & Water Solutions for Home & Village
http://www.villagepower.com
gosolar at villagepower.com
NABCEP (tm) Certified Solar PV Installer

530-470-9166
877-SOLARVillage
877-765-2784
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Shutesbury, MA 01072
425 Nimrod St.
Nevada City, CA 95959
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