Drive Maintenance (General Inspections and Repairs)
Improper Drive usage (installation and/or operation) and lack of maintenance (including failure to adjust based on changes in operating conditions) could shorten the service life of a Drive and/or cause Drive failure or faults. The impact of temperature, humidity, dust, and vibration could lead to poor heat dissipation and component aging of Drives (resulting in potential failure or reducing the service life of the Drive). This makes general inspections and maintenance particularly important (it is recommended that periodic inspections should be conducted at least once a year). Also ensure the correct size Drive is selected for the operation/application – please details HERE.
Before inspecting a Drive, ensure the power supply is cut off (ensure the power indicator of the Drive is off). Wait for approximately 15mins to ensure internal capacitors are discharged.
GENERAL INSPECTIONS and VERIFICATIONS
Take note of the Temperature and Humidity of the surrounding environment. Please see details regarding Drive Derating due to Temperature/Altitude/Humidity HERE. Excessive temperatures could cause the Drive to overheat (typically cause an Error alarm). In severe cases, it could damage the Drive’s power components and even cause a short circuit. Inspect for any possible moisture or dirt/dust evident inside the Drive, especially on the circuitry (which could cause short circuits). Excessive humidity could also cause a short circuit inside the Drive.
Check that all components are clean and for any signs of corrosion. If it’s evident that there is a lot of dust or moist inside the Drive itself, open the Drive and clean it.
Inspect all connections and ensure there aren’t any loose screws, bolts, or plug-in’s, also ensure that none of the conductors or insulators are corroded (if necessary, clean by wiping them off with alcohol). Also check for any signs of arcing on any of the component terminals. Ensure that all wiring and contactors/breakers are according to specification – please details HERE.
Also ensure that Shielded/Screened cable (cable with a common conductive outer layer for electromagnetic shielding) is used when connecting a Drive with any external instrumentation (such as PLC’s, Transmitters, etc.).
When the Drive is running, listen for any abnormal sounds or vibrations from the Drive and Motor. When the Drive is running, ensure the built-in Drive cooling fans are working properly (ensure there are adequate air flow and listen for any abnormal sounds or vibrations). Remove the Drive cooling fan/s if necessary and remove any dust deposits that might be present.
Drives (with IP20 rating) are generally installed in cabinets/enclosures/panels, which should also include adequate ventilation and cooling for the Drive. Please see Drive Cooling/Panel Fan Selection details HERE. Also ensure these fans operate smoothly (ensure there are adequate air flow and listen for any abnormal sounds). Ensure that the fans rotate smoothly, rotates in the correct direction (extraction fans should extract hot air out of the enclosure and not suck air in) and that there are no dust or obstructions in the air inlets. Clean the ventilation ducts and fans if necessary and remove any dust deposits that might be present (also remove dust from filters).
Other external aspects to inspect includes all other Drive peripherals that might be installed such as Reactors/Chokes, Filters, Brake Units/Resistors, etc. Ensure none of these components are overheating (could possibly see or smell burning/overheating) or make any abnormal noises. Also check the electric motor for possible issues.
GENERAL COMPONENT REPLACEMENTS
Drives are composed of various components, for some of these the lifetimes will gradually reduce as they age due to long-term usage, which could ultimately cause Drive faults and/or failure. The most vulnerable parts of Drives include the Cooling Fans and DC Bus Capacitors. The service lifetimes of these components are closely related to and dependant on the impact of the environment, usage conditions and regular maintenance, but below are general indications of their typical lifetimes:
- Cooling Fan: 3 ~ 4 Years / 30 000 ~ 70 000 Operating Hrs
- DC Bus Capacitor (Electrolytic Capacitor): 5 ~ 6 Years
To ensure the long-term normal operation of the Drives, these components should be replaced as required.
Cooling Fans
The power module of the Drive is the component that generates the most heat. The heat generated by continuous operation must be discharged in time using Cooling Fans. Possible damage of a Cooling Fan includes bearing wear and blade aging, please check for any cracks in the fan blade and any abnormal vibration and sounds during the operation of the Cooling Fan. Please pay attention when replacing a Cooling Fan to ensure it is the same specification as the original Cooling Fan (AC/DC, Voltage, Amps, CFM, RPM etc.) and to connect the wiring correctly. A good indicator of an already failed/damaged Cooling Fan would be when a Drive trips with Error 14 (IGBT Module Overheat).
DC Bus Capacitors
The DC Bus Capacitors’ (Intermediate DC loop filter capacitors / Electrolytic capacitors) main function is to smooth the DC voltage and absorb the low frequency harmonics in the DC circuit. The heat generated by its continuous operation plus the heat generated by the Drive itself will accelerate the drying up of its electrolyte (electrolyte aging). Other impacts on the Capacitor lifetime include poor quality of the input power supply, high external temperatures, and frequent changes in load. This directly affects capacity and, generally, if the capacity is reduced by more than 20%, the Capacitors should be replaced. Test Capacitors using a Multimeter set to Capacitance testing and connect the red and black probe to each connection point of the Capacitor. Readings should align with the Capacitor technical specifications as indicated on the Capacitor itself. A good visual indicator of an already failed/damaged Capacitor would be when there are signs of leakage of the Capacitor Liquid or if the Capacitor Safety Valve is protruding.
