Freezing cold, intense heat, vibration, corrosive chemicals! Drives can end up working in some really tough environments. It’s impossible to know what sort of dangers drives will face after they leave the factory.
Manufacturers design VFDs for durability and then test them to ensure they will perform according to specification over their whole lifetime. Below are some of reasons VFDs failures:
Capacitor Wear and Tear
Limited Life Sapn. The first reason for inverter failure is electro-mechanical wear on capacitors. Inverters rely on capacitors to provide a smooth power output at varying levels of current; however electrolytic capacitors have a limited lifespan and age faster than dry components. This in itself can be a cause of inverter failure.
Temperature. Capacitors are also extremely temperature sensitive. Temperatures over the stated operating temperature, often caused by high current, can reduce the life of the component. However, as the electrolytes evaporate faster at higher temperatures, capacitor life increases when they are run at lower than operating temperature.
Keep Capacitors in Good Health. Following a consistent maintenance regime and regularly replacing capacitors avoids most problems that failed capacitors can cause.
Overuse / Stress
Using inverters beyond their operating limit, either by choice or due to oversight or lack of knowledge, can contribute to inverter bridge failure. Using any component at a rating higher than its operating limit will decrease its lifespan and lead to failure, so avoiding this issue simply comes down to checking that all inverters are being run correctly.
Over and under Voltage and Current
The next two issues that can cause inverter failure are over-current and over-voltage. If either current or voltage increases to a level that the inverter is not rated for, it can cause damage to components in the device, most frequently the inverter bridge. Often this damage will be caused by the excess heat generated by the spike in voltage or current.
Over-current can be avoided with fuses or circuit breakers but avoiding over-voltage can be tricky. Sometimes voltage spikes are man-made, but they can also be caused by lightning or solar flares which are difficult to avoid. Like us, VFDs live on planet Earth!
Ultrasonic Vibrations
The final problem on the list is the one that contributes to the mechanical stress placed on an inverter. Ultrasonic vibrations originating in the cores of inductive components cause friction, adding to the unwanted heat generated by the device and further damaging components in the inverter.
Other items that cause failures are loose connections, moisture and failed fans. Although heat was mentioned in another category, these items fail often enough to warrant being specifically mentioned.
Axxa has qualified and experienced AC Drive repair, DC Drive Repair and Soft Starter Repair teams. Please Contact US or call us at (716) 270-0047 for all your VFD repair needs.
