ANL / AErr Analog Input Signal Loss fault in delta drive

ANL / AErr Analog Input Signal Loss fault in delta drive troubleshooting

Description

ANL (or AErr on some displays) indicates a loss of the analog control signal. This is specifically relevant when the drive is controlled by a 4-20mA signal (AVI or ACI). The drive monitors this input; if the current drops below a threshold (usually 2mA or 4mA), it interprets this as a broken wire rather than a "zero speed" command.

Causes

1. Broken Wire: The cable carrying the 4-20mA signal from the PLC or sensor has been cut or disconnected.
2. Sensor Failure: The pressure transducer or flow meter generating the signal has lost power or failed.
3. Loose Terminal: The ACM (Analog Common) or ACI terminal screw is loose.
4. Source Impedance: The PLC output impedance doesn't match the VFD input impedance settings (switch AVI/ACI settings).

Solution

Troubleshooting the control loop:
1. Measure Amps: Use a multimeter in Series (mA mode) or check the voltage across the input resistor (if 2-10V). If the reading is 0mA, the source is dead or the wire is cut.
2. Check Switches: Delta drives have physical DIP switches behind the keypad (SW1/SW2) to toggle between Voltage (0-10V) and Current (4-20mA). Ensure the switch matches the parameter settings.
3. Software Filter: If the signal is noisy and dipping briefly, increase the ACI Filter Time Constant parameter.
4. Disable Protection: If you are testing with 0-10V but the parameter is set to detect <4mA, turn off the AErr detection mode in Group 03 parameters.