An "AP4" AI4 4-20 mA loss warning in Schneider drive indicates a loss of signal on Analog Input 4 (AI4). This means the drive isn't receiving a current within the expected 4-20mA range on that specific input terminal.

"AP4" "AI4 4-20 mA loss" warning on a Schneider ATV950 drive indicates that the analog input AI4 is not receiving a valid 4-20 mA signal. This warning typically arises when there's an issue with the current loop, such as a disconnected sensor, broken wire, or a malfunctioning signal source.

Steps to Troubleshoot and Resolve AP4 AI4 4-20 mA Loss Warning:

1. Verify Signal Source:

   • Check the device or sensor that is supposed to provide the 4-20 mA signal to AI4. Ensure it is powered and operational.

2. Inspect Wiring:

   • Examine all wiring and connections between the sensor and the AI4 input on the drive. Look for loose, broken, or damaged wires. Ensure all connections are securely tightened and there is good contact at all terminals.

3. Measure Current:

   • Use a multimeter to measure the current at the AI4 input. Verify that it falls within the 4-20 mA range. If the current is outside this range, it will trigger the warning.
   • Check for continuity in the current loop to ensure there are no breaks or interruptions.

4. Check Parameter Settings:

   • Verify that the AI4 input is configured correctly in the drive parameters. Ensure that AI4 is set up to receive a 4-20 mA signal.
   • Review and adjust parameters related to AI4, such as input scaling, signal range, and any fault detection settings associated with AI4.

5. Inspect Signal Conditioning (if applicable):

   • If there are signal conditioning devices (like isolators or converters) in the current loop, ensure they are functioning correctly and not causing the issue.