Siemens Variable Frequency Drives are a staple component of many commercial and industrial applications in which motors run to complete the tasks. These drives can control and protect motors and offer energy savings in some applications. However, in every system, VFD can fail. Here, we are going to explain to you some Siemens VFD troubleshooting techniques to get running.
Siemens VFD Troubleshooting Guide
You can perform the Siemens VFD troubleshooting by checking the electric motor and VFD terminal connections. Variable Frequency Drive connections and motor can be loose, overloaded, or might be wired to the incorrect terminals. So, you should check all connections before go through the repair replacement process.
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Troubleshooting Diode and IGBT
Before giving power to the VFD, the input and output power sections need to be tested. If power is applied to it and there is any short on the input or output side of the variable frequency drive, further damage can be caused to the drive. You can use the special meters to test the input and output sections of the drive properly. If you noticed the short, disassemble the VFD and diagnose the cause for it. You can be done replacement if the repair is too costly.
Initially, you have to be done the checking of input and output sections. If these are in good condition, you have to apply the power to the VFD to perform amplitude reading and output frequency testing. You need to know the accurate meter readings by slowly increasing the voltage during the troubleshooting process and protecting the motor.
You should increase the power voltage on the VFD until the rated input voltage is reached. If your VFD has a display, you can check on it which further action you will need to do. If there is no display, disassemble and diagnose the internal power supply of the drive's control section. In this way, you can know further evaluate the cause of failure.
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Troubleshooting with Motor
If the above are healthy in your troubleshooting process, you have to perform the basic JOG/ RUN function of the drive with a simple template program. When you want to do this, back up all existing programs which are stored in the drive before installing a test template program for this test run process. If you take the backup of the Siemens VFD program, it will help you while reinstallation. The backup method will totally depend on the series and model of your variable frequency drive.
Once the programs have been backed up, the VFD needs to reset to factory defaults by using the keypad. After completion of reset to factory default settings, a basic START or STOP is recommissioned of the VFD connected to its motor. Moreover, you must perform the closed-loop testing when an encoder is involved. If still the motor is not running, test the output voltages and motor current ratings to know whether the drive is functioning properly for motor rotation.
Contamination is a preventable cause of VFD failure. So, you need to check your variable frequency drive for the contamination of moisture, dust, or any other airborne particles that may be electrically conductive. Tracking or arcing marks across components or circuit board traces indicate evidence of contamination failures. If contamination is excessive, the VFD must be isolated from the contamination source by providing an appropriate NEMA-rated enclosure or changing the environment. If there is any significant airborne contamination from dust, corrosive vapors, moisture, the drive should be at least a NEMA 12 enclosure.
Additionally, you have to check the internal cooling fans and component heatsinks of the device for contamination. As blocked fans force the drive to operate out of its temperature specification, it causes premature failure. However, the interior & exterior of the Siemens VFD, fans, blowers, filters, and heatsink fins should be cleaned monthly to avoid the risk of failure from contaminants.
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The environment of the VFD unit should be operated within specified temperature limits. You have to measure the temperature inside and outside the enclosure. Ensure that the temperature is within the ambient specifications determined by the manufacturer. If it is failed to meet the temperature specifications, it may lead to premature variable frequency drive failure because numerous power components rely on adequate cooling for proper operation.
You have to add additional cooling or relocate the drive unit to an area where ambient temperature within limits if the ambient temperature is too high. Although, low ambient temperatures form condensation and cause component/ VFD failure.
How long will a VFD last?
Most brands of VFDs have 5 to 12 years of life. But there are many factors to affect the lifetime of a VFD. Other components such as fans, capacitors, etc. have a finite life and will fail. Then, you need to replace them.
How do I clear a VFD fault?
Your VFD responds to a fault by coasting to stop and turning off output power to the motor. Auto-reset function reset automatically after some time. Then, the drive will restart.
Can you run a VFD with no load?
You can run the VFD without any load connected, especially if running at open-loop V/Hz mode. Move and program it. Some drives have an automatic feature that senses your motor winding characteristics so skip that part until you have the actual load connected.
Many Siemens VFD failures are caused by misapplication of the drive process changes like variations in load or speed, power issues, or changes in environmental operating conditions. You need to evaluate the consistency and condition of the VFD process when trying to determine the cause of failure. If the Siemens VFD problems are remaining, you can contact the manufacturer's technical support staff. You can select and order Siemens replacement parts from here.