Industrial drives such as the VFDs (Variable Frequency Drives) and servo drives have become an important element in industrial automation operations. However, when deciding to replace your faulty industrial drives with either new or spare drives, it is necessary to verify and conduct tests on the drive prior to installation.
Unlike brand new machines, used industrial drives may have undergone some tough environments during their time period from storage to use. There could be moisture, dust deposits, faulty capacitors, or improper handling, affecting their performance once installed into the systems. It might result in some problems being experienced in the system since they have not gone through inspections.
Testing and verifying the spare drives follow several procedures, including checking the machine visually and testing its electric components. Verifying the settings, parameters, and conducting the load tests can help you to get better results during the testing process.
Step-by-Step Inspection of Used or Spare Industrial Drive:
1. External/ Internal Inspections
Before conducting a detailed inspection of any used or spare industrial drive in an industrial automation or marine automation setup, it is crucial to conduct a visual examination of the drive before applying power. The industrial drive should be visually inspected internally and externally for any physical damage or wear and tear signs. Parts like the printed circuit board (PCB), cooling fan(s), heat sink(s), and capacitor(s) have to be thoroughly inspected for burn signs, discoloration, swelling, or even leakage. Dust and oil accumulation, as well as rusting due to the high humidity levels, may greatly affect the functioning of the circuit breaker systems and the electronic circuits.
2. Drive Identification/ Name Plate Verification
Drive identification/ nameplate verification guarantees that the drive will fit into the industrial automation application properly. Each drive comes with a nameplate that indicates the drive's vital information like voltage rating, current rating, frequency, power capacity (in kW or HP), and phase configuration. For instance, the drive nameplate specifies whether it is three-phase or single-phase. The nameplate is essential since using a wrong drive can cause inefficient operations, overheating, or even destruction of the motors.
3. Storage History and Environmental Effects
Storage history is one of the most significant factors in evaluating the usability of an industrial backup drive. Drives which have experienced storage in high-humidity, hot, cold, and dusty environments can experience internal degradation because moisture may cause corrosion of the circuit board, where-as storing a drive without energization can affect capacitors of the drive power circuit. In cases where industrial automation or marine automation is used, the effect of degradation is that drives cannot function efficiently due to instability and may stop working suddenly.
4. Cleaning and Preventive Maintenance
Cleaning and preventive maintenance are important aspects that ensure the drive attains its optimum performance state after refurbishing having been used. Contamination such as dust tends to accumulate inside the industrial drive hence interfering with airflow and making the process of cooling difficult. Consequently, the problem of heat accumulation in the drive becomes evident especially in parts such as PCBs and power modules, thereby triggering malfunctioning. The use of dry compressed air and suitable equipment during cleaning ensures no harm is done to the electronic components. In marine automation, cleaning becomes a necessity due to salt deposits.
5. Terminal and Electrical Integrity Test
Terminal and Electrical Integrity test involves testing the stability of all electric terminals inside the industrial drive. Poor or damaged terminals may lead to arcing, heating up of the terminals, and failure of the drive in operation. Proper tightening of power terminals, motor output terminals, and control connection terminals should be done. Grounding (earthing) is vital in both industrial automation and marine automation to facilitate safe operations and correct functioning of circuit breakers. Discoloration or any form of heating should alert the technician about past electrical problems.
6. Insulation Resistance (Megger)
The process of insulation resistance checking through a megger is a critical one to ensure that the electrical integrity of the industrial drive remains intact. This method determines whether there is any leakage current that will endanger the efficiency and safety of the equipment. In the case of used or spare drives, the insulation material might deteriorate due to prolonged exposure or the aging process. In a setting of industrial automation, high insulation resistance is necessary to prevent any short circuits or other electrical failures. However, caution should be exercised during this process to ensure that control circuits are not exposed to high test voltages.
7. Pre-Power Tests
These tests are carried out immediately before connecting power to the industrial drive in order to reduce any hazards during start-up operations. This step involves checking connections, voltages, and grounding once more. During the pre-power test phase, the drive must be disconnected from the motor in order to avoid any accidental movement of machinery during testing. In cases of automation in industries as well as maritime automation applications, incorrect voltage supplies and wrong wiring cause circuit breaker tripping and equipment failure.
8. Power-Up Testing (No Load)
The testing process that involves turning the power supply of the industrial drive system without connection of the motor is called power up testing without load. The reason why the industrial drive system needs to go through this process is that the user gets to know how the internal processes of the drive work without any danger. During this stage, one needs to analyze how the display panels function and look out for any warning messages. The cooling fan, relay, and other internal components must operate normally without producing any unusual sounds or overheating issues.
Today's industrial drives (such as VFDs, servo drives, etc.) play an important role in many automated manufacturing processes and maritime operations by providing accurate motor control, energy efficiency, and stability. But if the replacement of any failed component is to be carried out through the installation of secondhand industrial drives, then simply installing the drive is likely to lead to performance problems, downtime, and failure. Thus, testing and assessment of any secondhand industrial drive becomes important.
When compared to any brand-new industrial drive, used industrial drives might have suffered from adverse environmental conditions that can cause wear and tear in some crucial components of the system, such as capacitors, printed circuit board (PCB), and power modules. This will eventually affect the performance of the system by overheating, malfunction, circuit breaker trip, and even damage to associated motors or machinery.
The blog provides a comprehensive process that one can undertake when inspecting used industrial drives for safe operations. First, one must begin with the assessment phase where the drive will be inspected for any visible form of damage or other indicators of wear and tear. After that, one proceeds to the nameplate validation stage, whereby checks are performed to see if there are discrepancies such as incorrect readings of voltage, current, power rating, or phase. The drives are vital because they are used in automated systems.
The third procedure is the assessment of the storage conditions and history to find out whether there were any indicators of internal decay resulting from prolonged storage or moisture presence. Cleaning and maintenance should be conducted to prevent dust or any contaminants from interfering with the cooling system.
The procedure makes it clear that terminal testing and electrical checking have to be carried out to make sure that all terminals are fastened properly and that there is grounding so that the machine works efficiently. One of the other important stages in the process is megger testing, which prevents leakages and short circuits, thus ensuring proper operation of the drive.
Pre-powering tests can also be carried out before starting the drive for ascertaining that everything has been done right concerning connections, supply of voltage, and isolation of the drive from the motor. The final step would involve conducting power-up tests on the drive without using the motor.
