What are the specific steps for insulation resistance testing?

Insulation resistance testing requires a 500VDC megohmmeter. The procedure involves five steps: power off, disconnect, connect, apply pressure, and read the value. Especially in the high-temperature and high-humidity environment of Wuhan, it is essential to ensure the sensor is powered off and pre-dryed before testing to avoid misjudgment.

1. Pre-test Preparation (Safety First)

System Power Off: Turn off the power to the temperature control system to prevent high voltage damage to the control module during testing.

Sensor Removal: Disconnect the connection cable from the main control board and remove the sensor body from its installation position.

Surface Cleaning: Wipe the connectors, housing, and signal cable terminals with anhydrous alcohol to remove stains and moisture.

Air Drying: Place in a dry, ventilated area for at least 30 minutes, or purge with nitrogen for 5 minutes to remove surface moisture.

2. Test Equipment and Wiring

Use a 500VDC megohmmeter: Do not use a multimeter or low-voltage tester; a dedicated insulation tester must be used.

Correct Wiring Method:

Positive (+): Connect to both ends of the sensor signal line (short-circuit thermocouple poles);

Negative (-): Connect to the sensor's metal casing or armor layer;

Ensure Good Contact: Ensure the clamps are securely tightened to prevent contact resistance from affecting the reading.

Closed-Loop Operation: Before testing, use the megohmmeter's self-test function to verify the equipment is functioning correctly and ensure data reliability.

3. Pressure Testing and Reading Recording

4. Result Judgment and Follow-up Processing