Adjustable Speed Drive Repair

Checking connections is a step many people miss or do incorrectly during anadjustable speed drive repair process. Heat cycles and mechanical vibration can lead to sub-standard connections, as can standard preventative maintenance practices. Reusing torque screws is not a good Idea, and further tightening an already tight connection, can ruin the connection. Bad connections eventually lead to arcing. Arcing at the drive input terminal can result in nuisance over voltage faults, clearing of input fuses, or damage to protective components. Arcing at the drive output terminal could result in over-current faults or even damage to the power components.Loose connections can cause erratic operation. For example, a loose START/STOP signal wire can cause uncontrollable drive starting and stopping. A loose speed reference wire can cause the drive speed to fluctuate, resulting in scrap, machine damage, or personnel injury.

Conduct Diode and IGBT Tests
There are a number of methods to test the input and output power sections of an ajustable speed drive, and this step is essential prior to applying power to the drive unit. If for any reason there is a short on the input side or output side of the drive, further damage can be caused to the unit if power is applied to it.For this reason, Precision Electric uses meters to properly test the input and output power sections of the adjustable speed drive prior to applying power to the actual unit. If a short is found, the unit can be disassembled and the cause of the short can be diagnosed and quoted for repair. If the repair is too costly, then a replacement is offered to the customer.

Power Up Unit
If the input and output power sections on the adjustable speed drive test healthy during this step of the repair process, Precision Electric will power the unit and perform amp reading and output frequency tests. Precision Electric prefers to slowly increase power voltage to the unit until the rated input voltage of the drive is achieved. Depending on whether or not the adjustable speed drive provides a display will determine what further action(s) will be taken. If display is unavailable, disassembly and diagnosis of the internal power supply of the control section of the drive is likely necessary to further evaluate cause of failure and establish cost and lead time for the repair.

Run A Motor
If the previous three tests have passed during the adjustable speed drive repair process, then it is time to run a basic jog function of the drive with a simple template program. Often when an adjustable speed drive comes into our facility, we make sure to backup all existing programs stored in the drive prior to inputting a template program and running a test procedure. This ensure we have a backup copy of the program.The best method for backing up depends on the brand of drive, but after it has been backed up, we either reset the adjustbale speed drive to factory defaults through the keypad and recommission a basic start, stop and job application or closed loop if an encoder is involved. If the motor will not run, it will be necessary to check the output voltages and current ratings going to the motor to see if the drive is functioning properly to rotate the motor.

Contact Customer
At this point we have determined the cause of failure, estimated lead time and cost of the adjustable speed drive parts that need replaced, and are ready to offer the customer our repair quote. If the adjustable speed drive has tested good entirely, then further underlying issues are communicated with the customer. This is when Precision Electric will gather application specific information from the customer to establish whether or not it may be some outside issue associated with the system including, but not limited to, PLC communications, faulty I/O, bad wiring or even bad cabling. There is no single way to do this step since it depends on a wide variety of variables.

Routine Maintenance
Most adjustable speed drive repair can be prevented with routine maintenance. Adjustable speed drive repair cost and lead times can also be reduced with routine maintenance. Adjustable speed drive repair can be expensive and also cost manufacturers production downtime during the repair process. Most manufacturers keep spare drives in stock to prevent production downtime when their adjustable speed drive repair is in process.

Adjustable speed drive repair should be taken with extreme caution. Adjustable speed drive repair should only be performed by technicians who have required training and experience to work with electrical equipment. Precision Electric strongly recommends to consult an expert in the field when repairing all industrial electrical equipment. Many drive controllers have an internal DC bus that retains a charge after power has been cut to the drive, as a result, it does not mean it’s safe to work with. Technicians working with drive repair must always take extra precautions to ensure proper safety measures are taken, or injury or even death may occur.

For adjustable speed drive repair and replacement quotes, contact Precision Electric, Inc.

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