Correct Operation of Megohmmeter for Electronic Ballast Insulation Test

 Preparations

1. Select a 500V megohmmeter. Do not use 1000V or higher to avoid breaking semiconductor components.

2. Cut off all power, disconnect power wires, UV lamp cables and control wires, and remove the UV lamp load.

3. Dry the ballast thoroughly if damp; test only after conformal coating or potting glue is fully cured.

4. Wear anti-static wristband to protect PCB components.

2. Wiring Method

1. Short-circuit all input and output terminals of the ballast together.

2. Connect the megohmmeter terminal L to the shorted terminals.

3. Connect terminal E to the metal housing or ground screw of the ballast.

4. For severely damp bare PCB, connect terminal G (shield) to the PCB insulation layer to eliminate surface leakage interference.

3. Standard Test Operation

1. Do not touch the metal probes during measurement to avoid human shunting.

2. Hand-crank megohmmeter: turn steadily at about 120 r/min for 30–60 seconds and read stable value.

3. Digital insulation tester: switch to 500V mode, start test and wait for stable reading.

4. Record insulation resistance data.

4. Post-test Safety Steps

5. Judgment Standard

• ≥5 MΩ: Qualified for installation

• 1～5 MΩ: Slightly damp, re-dry and re-seal for retest

• ＜1 MΩ: Unqualified, forbidden to power on

6. Important Prohibitions

• Never test with power connected

• Do not test before drying or glue curing

• Do not adopt test voltage over 500V

• Keep hands away from metal measuring points during testing