2. Use an AC voltmeter or a multimeter set to AC volts. (Any AC meter should be sufficient. It does
not need to be a “true RMS” meter.)
3. Measure between each combination of two pump wires (L1–L2 / L1–L3 / L2–L3).
4. Voltage should be 20-60VAC, depending on the power available and the load. Each reading
should be equal.
Test the motor circuit (resistance test with power off)
This resistance test will confirm the condition of the entire motor circuit, including the motor, pump
cable and splice. Make this test if there is proper voltage at the controller input but the motor does not
run.
1. Disconnect power from the controller.
2. Disconnect at least two of the three pump power wires from the junction box terminals.
3. Use a multimeter set on resistance (RX1 or
Ω
).
4. Measure between each combination of two pump wires (L1–L2 / L1–L3 / L2–L3).
5. The resistance should be .1 to 1 ohm (
Ω
), depending on the length and size of the pump
cable. EACH READING MUST BE EQUAL.
6. NOTE — Resistance between meter probes and wires can produce an erroneous reading.
Hold the probes tightly to the wire and scratch them to ensure good contact. Hold them still
until the meter display shows the LOWEST reading that you can get. Holding the probes with
your fingers will not alter the reading.
7. Measure resistance between the ground wire and the motor wires. Your meter should show
either no reading, or more than 100 MW (that means 100 million
Ω
or 100 megohms). A
lower reading indicates an insulation fault in a power wire to the pump.
9.4 If The Pump Runs But Flow Is Less Than Normal
1. Is the solar array receiving shadow-free light? (It only takes a small shadow to stop it.) Is it
oriented properly toward the south, and tilted at the proper angle? See Section 3.
2. For water-lifting applications, be sure you have the right pump for the total lift that is required, out
of the vertical height up the hill.
3. Be sure all wire and pipe runs are sized adequately for the distance. Refer to an appropriate wire
sizing table, and to a pipe sizing chart.
4. Inspect and test the solar array circuit and the controller output, as above. Write down your
measurements.
5. There is a “max. RPM” adjustment in the controller. It may have been set to reduce the flow to
less than the normal setting “position 2” shown in Section 4.6.
Has the flow decreased over time?
1. The pump end (pump mechanism attached to motor) may be worn from abrasive material (sand,
silt, clay) in the water. Is sediment accumulating in the water tank or pipes?
2. Inspect the pump’s intake screen or foot valve. It may be clogged with debris, especially in a
surface water source.
3. If there is a check valve at the pump’s outlet, inspect it to see if sand or silt is blocking the flow.
The pump may be running in reverse
The pump may produce partial pressure and a slight flow if it is run in reverse. Motor reversal only
happens if the pump is wired to the controller improperly. See Section 4.8 “Wiring Order for Correct
Rotation”.
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