Variable Frequency Drive (VFD) Routine Maintenance Checklist

1st July, 2025.

In this post, we will see the steps to routinely maintain the variable frequency drive with proper checklists.

VFD is the most used component in industrial automation applications. It is used to vary the speed of the motor as required in a desired frequency. But, as an electronic device, VFD too requires it’s routine schedule of maintenance. Otherwise, the plant operations are compromised if the VFD fails considerably. And as the motors are the running life of any industrial process, shutting it down can hamper the business in a long way. So, it is required to routinely check the VFD as frequently as possible, with the checklists to be followed when testing. In this post, we will see the variable frequency drive routine maintenance checklist. Let us divide this routine into daily, monthly, quarterly and annual.

Daily VFD routine maintenance checklist:

1. The very first step is to check for LED indications on the VFD. VFD has standard LEDs like run, fault and stop. If the fault LED is on, check for the alarm generated and address the issue. LEDs are the best way to troubleshoot any device, and so, also keep it’s manual or catalogue in handy.

2. Carry a visual inspection of the VFD by checking it’s rust or dust condition, any foreign objects present on the body, corrosion, burns, loose wires, broken insulation or any physical damage.   

3. If your motor data is communicated via PLC to your database, then check for critical motor parameters like current, power, voltage, frequency, motor RPM, IGBT temperature, load %, output temperature and torque. Ensure that required graphs are generated in the SCADA or HMI application for tracking the same, thus easing your work and helping in precise maintenance.

4. Check for fan noise. Fan is the component inside VFD which runs continuously. So, fans can tend to get damaged or faulty over a period of time. If the fan is not resolved, then the cooling of the VFD will be compromised, thus resulting in overheating and damage to the VFD.

Monthly VFD routine maintenance checklist:

1. Filters are an important part of VFD, as they help to clog the dust, dirt and other foreign materials outside only and not enter the interiors of VFD. Ensure to clean the filter in power off condition and check that it is not clogged even after cleaning. This will ensure consistent airflow and extend the lifespan of the VFD.

2. Check the grounding connections of the VFD in power off condition. Improper earthing can damage the VFD to a very large extent. Inspect the neutral to earth voltage in the panel, earth wires connected in the VFD, and earth continuity with the earth pit.

3. Check the environment around the VFD. Try to maintain the ambient temperature around it, keep the humidity below, checking for any vibration source nearby which can create noise in the VFD operation, and ensuring the area is clean without dust, oil mist or moisture.

4. Visually inspect and clean the heatsink if required. Use compressed dry air or ESD-safe brush for this purpose. This ensures that your internal cooling is maintained inside the VFD.

Quarterly VFD routine maintenance checklist:

1. Make a quarterly log of the VFD data which you were observing daily, in a log book or digital. This will help you identify the frequency of any abrupt performance and how many hours the VFD has actually worked correctly. This step helps in preventive maintenance in a great way, as you get a clear idea on how to rectify the problem area happening frequently.

2. Take the backup of the VFD log, like runtime hours, event logs and other accumulated data with USB or external connections, and store it in your PC or laptop. This helps you keep the last backup of the VFD and aids in restoring it in the event of any failure.

3. Clean the VFD and keep it dry as much as possible. Do this in power off condition. Cleaning can be done by low-pressure compressed air, or using dry cloth. This helps the VFD prevent itself from external dirt accumulated over a period of time. 

Yearly VFD routine maintenance checklist:

1. Check the status of the capacitors. This ensures that the internal DC bus of the VFD is working fine. Without these capacitors, the DC voltage inside the VFD would be unstable and full of ripples, leading to erratic motor behavior (it is converted to DC initially by rectifier, and then to AC back using inverter and semiconductors). Capacitors also absorb voltage spikes, surges and reduces DC ripple, thus helping to maintain a stable voltage. So here, you have to check the temperature of DC bus components, DC ripple graph, and measure capacitance using an ESR (equivalent series resistance) meter.

2. Check for firmware updates and if available, then update it accordingly. Check the setpoints set internally inside the VFD, and the communication network health. Consult the OEM before updating the firmware, as it is the most basic working thing for the VFD, and an improper firmware can degrade the performance of the VFD.

3. In electrical system checks, monitor the line voltage balance, use power quality analyser for testing total harmonic distortion, voltage sags and unbalance in voltage, observe PWM waveforms for frequency and duty cycle, and use insulation resistance testing or IR testing for any leakage in the insulation.

I have covered the steps to routinely check and maintain the VFD. I have also not attempted to cover all the topics related to it, as it can vary from case to case. Once you are familiar with this type of technology, you can easily troubleshoot any issues related to it.

Thank you for reading the post. I hope you liked it and will find a new way in this type of technology.