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On 2/24/2012 5:18 PM, jay peltz wrote: Hi Allan, Do I misunderstand you below that you are saying you don't need a LCB with a slow pump? Thanks, jay Jay, The answer turns out to be "definitely maybe". The Slowpump spec sheet says: "A linear current booster (controller) is required to start and run in low light." The manual says: "When working against a constant head (vertical lift) Solar Slowpump requires nearly constant current, regardless of the voltage/speed. When low light conditions are present, the PV array cannot supply full current. The voltage will drop to nearly zero, and the pump will “stall” (like a truck trying to start in 4th gear). The remedy is either to add a PUMP CONTROLLER, also called LINEAR CURRENT BOOSTER (LCB) to your system. This device will match the power source to the load by transforming the voltage down while increasing the current delivered to the motor (like an automatic transmission). If you are not using a controller in your non-battery system, contact your dealer. It will greatly improve low-light performance." See the last sentence. So, unsure about this, I called Windy. Here's what he said: "IF the motor is being used near its capacity, AND the pump stalls due to an unrelated obstacle (not just low-light stalling), AND the fuse is NOT sized just above the normal amp draw of the motor (say a 7A fuse on a 5A draw on a motor capable of pulling 20A) THEN the motor windings could overheat before the thermal switch could trip, and destroy the motor. So it's unlikely but possible, and probably a good idea. And it certainly lengthens the pumping day. Allan
Allan Sindelar
al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com
On 2/24/2012 5:18 PM, jay peltz wrote:
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