I agree that an inverter is your most viable voltage converter. There is
no good reason to go DC to DC that I can see. The other option would be
to switch the array to operate the pump directly. Use a Charge
controller that operates the array at the same voltage the pump needs to
operate at, and have an array transfer switch from CC to pump.
Ray Walters
Remote Solar
303 505-8760
On 8/21/18 12:24 PM, MDElectricSolar wrote:
Is there an inverter, you could power it with 120 or 240V AC?
On Tue, Aug 21, 2018 at 11:17 AM Gary Higbee <g...@windstreamsolar.com
<mailto:g...@windstreamsolar.com>> wrote:
Hi Wrenches,
I’m assisting a customer and well person in replacing a failed
Lorentz ETApump (after 15 years of intermittent use). We’re
looking for a quality DC-DC converter to power a not-yet- ordered
Grundfos SQFlex 6 SQF-3 from a 24 V Surrette battery bank (wish it
was 48!). The pump draws a max of 8.4A and the curves say we’ll
need about 600 watts so I figure we’d want at least 70 volts out.
Ideal would be a higher DC output, say 200V (save a couple hundred
feet of larger copper, greater efficiency) and at least 3A (see
questions).
The primary power source will be 240V AC but my customer wants a
fallback for battery operation. We plan to use the Grundfos IO 101
SQFlex switch box, which will switch to DC if the AC fails. Also
the CU 200 SQFlex control unit, so we can accommodate the existing
float switch up the hill, etc.
The Grundfos tech person I spoke with today said the DC system
should be able to supply 8.4A, regardless of the DC voltage.The
pump curve says we need 600W for maximum performance at the lift
we’ve got. It seems to me that if we’ve got 200V and need 600W
we’d be drawing 3A. Yet if the Grundfos factory line is there
should be 8.4A available that’s 1680W. The tech guy said he didn’t
have specific information why we’d need 8.4A regardless of pump
input voltage.
The Grundfos Product Guide says:
*Max. ratings are as follows:*
*• Maximum power input (P1) of 1400 W*
*• maximum current of 8.4 A*
*• maximum speed of 3600 rpm *(think I read somewhere it’s 3000
rpm for this helical rotor model)
*
*
*The pump delivers its maximum performance when **one of the above
parameters is reached.*
Two questions:
1) Do any of you have experience running the SQFlex on DC, and
what to make of the 8.4A at any input voltage factory
recommendation? Maybe basic amps/volts/power calculations aren’t
applicable given the pump electronics?
2) Are you aware of any DC-DC converters that will get us from a
nominal 24V battery bank to 200V, or somewhere between 70 and
200V, with an appropriate current limiting amp rating to get us at
least 600W (depending on thoughts regarding the above question)?
Thank you,
Gary
Gary Higbee
Windstream Solar
Oregon License 17LRT
Renewable Energy Consulting
g...@windstreamsolar.com <mailto:g...@windstreamsolar.com>
541-954-3881
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