Sun Pumps PCA-30M1D - Manual (Page 12)

With switch number 4 in the ON position, the controller is configured to accommodate a Normally Closed
(N.C.) float switch, pressure switch or remote toggle switch. In this configuration the controller will
operate as follows:
PUMP ON
switch closed = water tank low = pump ON
PUMP OFF
switch open = water tank high = pump OFF
Sensorless Low Water Cut-Off Circuit (LWC)
The Low Water Cut-Off Circuit (LWC) turns the pump off any time the controller output power drops
below a functional level. This protects the pump in stall conditions and saves wear on the system when no
or very little water is being pumped. This feature must be adjusted for your specific application.
This circuit works by monitoring the pump current. If the pump breaks suction the current will drop and the
controller will automatically turn the pump off and start a 30 minute timer. At the end of the 30 minutes the
pump will turn back on again.
Please note there are some draw backs to using this feature. Early in the morning and on cloudy days when
there is very little array current available, the controller may turn the pump off because of the low current.
This may cause the pump to start later in the morning or reduce the run time during the day. We
recommend only using the LWC feature if there is a known low flow rate water source. We would prefer to
use the motor speed control and adjust the pump flow rate to the output of the well.
LWC Adjustment for SDS Series Pumps
1. The system should be wired and the pump set slightly below the water level in the well.
2. Turn the number 6 dip switch off and then turn the pump on to fill the drop pipe with water. This
way you are adjusting the pre-set current to the actual load.
3.
Turn the “LWC” trim pot counter-clockwise until it stops. (Less than a turn).
4.
Now turn number 6 dip switch on.
5. With the pump turned on and pumping water, pull the pump out of the water. It will not damage
an SDS series pump to run dry for several minutes.
6. Very slowly turn the “LWC” trim pot clockwise until the pump turns off. This is now the set-
point where the pump will turn off.
7. To verify your adjustment, put the pump back in the water and turn the switch off and back on
again to reset the controller. If the adjustment is correct the pump will remain running while
pumping water and if pulled out of the water it should turn off.
8. Once the pump turns off it will not turn on again for approximately 30 minutes, unless manually
reset. To manually reset the timer, turn the On/Off switch off and then back on again.
Motor Speed Control
The Motor Speed Control circuit is used to control the speed of the pump motor and thus the flow rate of
the pump. It is primarily used for low producing wells where the pump output is matched to the production
rate of the well. However it can also be used any time specific flow rates are required.