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Q: Why is my pump showing (AC Out PH) or Phase Lost?

Step 1: Verify Inverter Phase Settings

The inverter must be programmed to match the specific phase of your pump motor.

  1. Stop the Pump: Press the On/Off button to ensure the system is not trying to run.
  2. Access Settings: Press UP or ESC until you see the model page. Press Enter and input password 0000 (or 9590 if that fails).
  3. Check Output Phase (230V Models Only): Navigate to the AC Output Phase setting (Password 9578).
    • If you have a Single-Phase pump, this must be set to "Single".
    • If you have a Three-Phase pump, this must be set to "Three".
  1. Save and Restart: After changing the setting, you must power-cycle the unit (turn the solar isolator off for 10 seconds and then back on) to apply the change.

Step 2: Perform a Resistance Test (Checking for Broken Wires)

A "Phase Lost" error often means one of the wires in your submersible cable has a break or a poor connection.

  1. Setup your Multimeter: Set the dial to Resistance (Ω).
  2. Safety First: Turn off all power and wait 5 minutes for electricity to discharge.
  3. Disconnect the Pump: Unplug the AC output plug from the inverter or disconnect the U, V, and W wires from the terminals.
  4. Measure the Motor Wires:
    • For 3-Phase Motors: Measure between U-V, V-W, and U-W. All three readings must be identical. If one reading is "OL" (Open Loop) or much higher than the others, that wire (phase) is broken.
    • For Single-Phase Motors: Measure the three combinations. The sum of the two lowest readings must equal the highest reading. If they do not add up, or a reading is "OL", there is a fault in the motor or cable.

Step 3: Conduct a No-Load Test

This test determines if the error is caused by the pump/cable or if the inverter’s internal hardware has failed.

  1. Keep the Pump Disconnected: Ensure the motor wires are still unplugged from the inverter.
  2. Power On: Turn the solar isolator back on and press the On/Off button.
  3. Check the Frequency: Navigate to the AC OUTPUT STATUS screen.
    • Healthy Inverter: If the frequency reaches the maximum set value (usually 50Hz) without the error reappearing, the inverter is healthy. The problem is in your pump motor or the submersible cable.
    • Failed Inverter: If the error reappears even with the pump disconnected, or if the frequency stays at 0Hz, the inverter's internal circuit has failed.

Summary of Skills Required

How to use a multimeter for this task:

  • To check Resistance: Dial to Ω. Touch one probe to the blue wire and one to the Black wire. Record the number. Repeat for Black to Brown and Blue to Brown.
  • To check Output Voltage (Advanced): Dial to AC Voltage (V). While the inverter says "ON (Working)", touch probes to the U and V terminals, then V and W, then U and W. For a 230V system, each pair should read roughly 230V-240V AC.

Safety Warning: Never connect a single-phase pump motor to a three-phase inverter, as this will cause permanent damage and trigger phase errors.