Variable Frequency Drive (VFD) Repair Process

Starting with making sure the drive terminal connections and electric motor connections are made correctly, a variable frequency drive (VFD/AC Drive/Servo) repair should be performed. Before removing the drive for a repair review, it is advised to verify all connections. Drive output, which is the motor connection, and drive input, which is the incoming power connection, can both be overlooked, mounted carelessly, or wired to the wrong terminals.

Subpar connections, or more precisely, loose connections, can be caused by load cycles and mechanical vibration during operation. Arcing and spark eventually result from loose connections. Arcing at the drive input terminal may cause excess voltage faults, input fuse clearing, or damage to safety features. Sparking or arcing at the drive’s input (L1, L2, L3), output terminals (U, V W), or DC point (DC+ & DC-) may cause overcurrent  faults or harm to power parts like the rectifier unit and IGBT Unit. Small stoppages or unpredictable functioning might be brought on by loose connections. For instance, an unpredictable starting and stopping of the motor may be caused by a loose START/STOP signal line. The drive speed may fluctuate as a result of a loose speed reference wire, which could lead to scrap, machine damage, and human injury.

Testing of Rectifier and IGBT Modules

The input and output power portions are examined before putting the Variable Frequency Drive back together. If power is provided to a drive that has a short on either the input side or the output side, the unit could suffer further harm. To correctly evaluate the input and output power portions of the drive before supplying power to the drive unit, specific meters should be utilized. If a short is discovered, the drive can be disassembled so that the short’s source can be identified and a repair estimate given. Drive replacement should be taken into consideration if drive repairs are too expensive learn more about VFD Repair, get in touch with us.

Charge up

Power can be applied to the drive to conduct amp reading and output frequency testing if the input and output power sections test positive for health throughout the variable frequency drive repair process. To obtain correct meter readings and to safeguard the motor, it is advised to gradually increase the power voltage during this stage of the drive repair procedure. Up until the drive’s rated input voltage is attained, the power voltage is gradually increased on the drive. The next course of action will depend on whether the drive offers a display or not. If the display is not available, it is required to disassemble and diagnose the drive’s internal power supply in order to determine the cause of the failure and its cost and lead time.

Motor evaluation

A straightforward template programmed can be used to execute the drive’s basic JOG/ RUN function if the preceding three tests during the variable frequency drive repair process have been successful. Prior to installing a test template programmer for testing, repair techs will backup any existing programmed that are saved on a drive when it arrives at our facilities. We can install a backup copy of the drive software after the repair is finished by backing up the programmed. The series and model of the drive that is being repaired will determine the optimal procedure for backing up drive programmed. The drive is reset to factory default through the keypad after the drive’s programmers have been backed up, and it is then recommissioned to a basic START/STOP function.

If there is a tachometer or an encoder, closed loop testing is required. The output voltages and motor current ratings are checked to make sure the drive is operating properly to rotate the motor if it won’t turn.

Safety Measures

Manufacturers are urged to confirm that any Variable Frequency Drive repairs are carried out on the premises of the company providing the service. Drive repairs should only be carried out by experts who have the necessary knowledge and experience to work with electrical equipment and should be done with the utmost carina

Automat Automation highly advises seeking advice from a professional in the area before repairing any industrial electrical machinery. Many drive controllers feature an internal DC bus that holds a charge after the drive’s power is turned off, thus electrical current continues to flow even after the power is turned off. When doing VFD repairs, technicians must always take additional care to make sure the right safety precautions are implemented, or else harm or even death could result. For more details, check Electrical Panel Cleaning.