There can be several reasons why the analog input is not varying in a VFD (Variable Frequency Drive):
The faulty analog input device
The analog input device, such as a sensor or transmitter, may be faulty or malfunctioning. It might not be providing a varying signal to the VFD, resulting in a static input.
Incorrect wiring or connections
Check the wiring connections between the analog input device and the VFD. Loose, damaged, or incorrect wiring can disrupt the signal and prevent it from varying.
Incorrect configuration
Ensure that the VFD is properly configured to accept and interpret the analog input signal. If the configuration settings are incorrect or incompatible with the input device, the VFD may not vary the output accordingly.
Input signal range limitations
Verify that the analog input signal falls within the acceptable range specified by the VFD. If the signal is outside the specified range, the VFD may not be able to vary the output accordingly.
Environmental factors
External factors such as electromagnetic interference (EMI), electrical noise, or environmental conditions can affect the analog input signal, leading to a lack of variation. Shielding the wiring or addressing environmental factors may help resolve the issue.
VFD programming or software issues
There might be a problem with the VFD’s programming or software that is preventing it from responding to changes in the analog input signal. Updating or reprogramming the VFD may be necessary to resolve this issue.
If you are experiencing a consistent problem with the analog input not varying in your VFD, it is recommended to consult the VFD’s user manual or contact the manufacturer’s technical support for further assistance. They can provide specific troubleshooting steps based on the VFD model and your specific setup.