Soft Motor Starts on Pumps [RE-wrenches]

[Jeff Clearwater]

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Travis,

I imagine you're right on the demand charges for the on-grid case - 
though the other benefits of soft motor starts may be worth it 
(equipment wear, piping trauma and water hammer on pumps, run-time 
efficiency gains - at least that's what the motor control sales 
powerpoint says! . . . )

  . . . . but actually what I'm really after is the inverter surge 
reduction on the off-grid case.

Thanks!

Jeff


>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
>72 Baker Rd.
>Shutesbury, MA 01072
>425 Nimrod St.
>Nevada City, CA 95959
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`~


-- 
~~~~~~~~~~~~~
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
72 Baker Rd.
Shutesbury, MA 01072
425 Nimrod St.
Nevada City, CA 95959
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`~

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