It's interesting how certain topics always seem to trend simultaneously. Earlier today, a post featuring the DC Bus was shared. Check it out here.
Thank you all for your input so far. This issue is a bit of a puzzle as I have never encountered it before. I am perplexed as to why both drives are not working. Alan and Badger, I will dismantle the drives tomorrow to investigate further. Nonuke, I have already disconnected all cables except the mains input and even connected the motor to a DOL contactor for testing purposes, which went smoothly.
John from CalderWood, I have a wiring diagram for the machine. The ABB VSD model is ACS310-03E-02A6-4SEW, while the SEW VSD model is MC07B008-5A3-4-00. I have left the site and am currently in my hotel room, feeling frustrated as all the pubs are closed. This has truly been the worst day of this month.
What type of main power supply is energizing the drive? If it is a resistive grounded neutral, there is a possibility that both drives may have been damaged due to overheating.
One common issue seems to be related to the input power of 2 failed drives, potentially caused by a lack of power or faulty fuses. It is important to check if the drives are properly protected by fuses by removing and testing them. Additionally, consider the possibility of back feeding from another load, which may give the false impression of adequate power. To troubleshoot, try powering the drives from a separate 3-phase source.
This situation is a real head-scratcher as I have never encountered it before. It's puzzling why two drives suddenly stopped working. I remember dealing with a similar issue related to a SEW motor. After the customer's contractor installed and burned through three expensive $3500 VFD drives, they called me for help. Upon inspecting the motor terminal box, I immediately noticed the problem without even having to use a megger on the wires. The culprit was the screw-terminal connectors on the SEW motor. The careless electrician had left strands of wire protruding, which caused a short-circuit and ultimately led to the destruction of all 3 replacement drives. It's crucial to pay attention to every detail when working with electrical connections to avoid costly mistakes and damages.
Make sure to carefully follow the special instructions in the manual when connecting the drive to floating or corner-grounded three-phase power. Failure to do so could result in burning up the CE noise filter section and damaging the drive. The CE noise filter must be used with a balanced-to-ground (grounded wye) power source or disconnected before powering up to avoid any issues.
holyhobgoblin, you mentioned that there was a 3 phase 430V supply, was this connected to the input terminals of the drive? Are there any fuses installed for the 3 phase power supply to the drive, and are they functioning properly? In a previous experience, I encountered a system where the drive would only activate when an enable contactor was engaged before the 3 phase power was supplied, followed by a start signal. Is there anything noticeable in the circuit based on the schematic diagram provided?
- 23-11-2024
- JohnCalderwood
If your 3-phase power supply was functioning properly and then suddenly stopped working, there may be an issue with your incoming power supply that is causing damage to the front end of your drives as soon as power is applied. This problem is often related to the design of the drives, which are intended for solidly grounded Wye (Star) systems and not Delta power systems. Drives with CE filters typically have MOV networks to protect the rectifier components. If the resistance to ground is lower than the grounding resistor, or in the case of a delta source, the only path to ground, the MOVs can be destroyed, leading to surges that damage the rectifier.
Another potential issue could be extreme common mode noise causing zero-cross notching, leading to immediate surges through the diodes and damaging them right away. This type of notching is often caused by older DC power controllers or AC controllers with GTO thyristors, which can force an SCR into a premature off condition.
Open transition Star-Delta motor starters, particularly on high-torque motors, can also cause damage. During the transition, a brief loss of torque can result in the motor slowing down slightly. When reconnected in Delta, residual magnetism can keep the motor in Regen mode, causing it to be out of sync with the line frequency and leading to a current spike that can damage nearby electronic components.
During commissioning, it is important to investigate any potential scenarios that could be causing these issues. If the problem only arises once the machine is fully connected to the power supply, it is likely the cause of the damage to your AC drives. It is important to thoroughly review your commissioning sequence to identify and address the root cause of these issues.
Thank you for the responses, everyone. Before leaving the site last night, we took both drives to the customer's other factory and connected them directly to a 3-phase power supply, but unfortunately, they did not show any signs of life. It appears that the drives are not functioning properly. The motor was tested for shorts and appeared to be in good condition. I connected the motor to a DOL contactor for testing, and it ran smoothly without any issues.
In Australia, most incoming supplies use a TN-C-S earthing system, which is referred to as MEN (multiple earthed neutral) instead of PEN. I checked the earth connection back to the sub-board and did not find any problems. Testing between the earth and each phase showed 240 volts, indicating that there is an earth connection back to the neutral link at the main board.
The motor is only 0.55kw, while the VSDs are rated at 0.75kw, and both can handle up to 480 volts input. I have arranged for someone to test a single-phase input instead of a 3-phase input to see if that resolves the issue. Other than that, I am at a loss for what could be causing the problem.
holyhobgoblin expressed gratitude for the responses received. After testing the drives at the customer's secondary factory with a direct 3 phase power supply, it was determined that the drives were unresponsive and likely faulty. The motor was tested for shorts and operated smoothly when connected to a DOL contactor. In Australia, the incoming power supplies typically use the TN-C-S earthing system, known as MEN (multiple earthed neutral) instead of PEN. Despite checking the earth connection back to the sub-board and finding no issues, there was a 240-volt reading between the earth and each phase, indicating a connection back to the neutral link at the main board. The motor is 0.55kw while the VSDs are 0.75kw rated and can handle up to 480 volts input. An attempt to use a single-phase input instead of a three-phase input is being made to troubleshoot the issue further. The presence of line noise problems is also being considered, along with the possibility of a reactor ahead of the drives.
Inspect the wiring connecting the drive to the motor to ensure there are no power factor capacitors attached. While it is unlikely, it is always best to verify. A motor of 0.55 kw should typically be wired in a star (wye) configuration on both the drive and direct online (DOL) starting method, so it is advisable to confirm this as well.
Have you conducted a smell test on these drives? If the displays are not turning on, it could be a sign that the power supply board or circuit responsible for running the VFD's internal components is malfunctioning. This is often accompanied by a distinct burning smell from overheated insulation or PCB materials. Issues on the load side typically lead to component failures, but it's uncommon for displays to be affected unless there was a catastrophic event. Line side problems, such as a high current spike on the DC bus, can result in a sudden failure of the PC board trace that feeds the DC-DC converter for control power. This type of failure can be silent but fatal for the drive.
Hello everyone,
I have thoroughly checked the motor and wiring for any issues, as mentioned in a previous post. I tested the motor on DOL and found no problems. When I suspected a blown component, I inspected both units but found no burn marks. The LED indicators on both units show that they are powered up. However, when I installed the new ABB drive, it did not light up at all. Despite this, after installing a single-phase input drive, everything is now working perfectly.
I am puzzled as to why both drives failed, so the company from which I purchased the ABB drive will be conducting an inspection and providing a report on their findings. To add to my already stressful situation, we missed our flight home.
I have a question regarding measuring line noise - can anyone advise on the best way to do this if it may be the underlying issue?
Thank you all.
Utilizing a scope or scope meter with rapid response time is crucial for analyzing the intricate workings of a single phase drive. The functionality of this drive piques my curiosity, as I am intrigued by the potential differences it can make and the mechanisms behind its operation.
The operation of a single-phase drive is quite intriguing. It is difficult to comprehend how it could make a difference in performance. One potential scenario could involve two legs of a 3-phase motor being partially shorted to each other, resulting in sporadic functioning. It is possible that the single-phase load is connected to one functioning leg and one faulty leg, ensuring consistent operation. Despite checking the earth connection back to the sub-board and finding no issues, a voltage of 240 volts between earth and each phase indicates a connection back to the neutral link at the main board. To thoroughly diagnose the situation, it is recommended to use a megohmeter to test each leg of the drive-to-motor cable for high-resistance short circuits between phases. This testing may reveal a partial short-circuit between phases.
I suspect that the drive may have a single-phase input and three-phase output. If the line power is delta corner grounded, it could be causing issues with proper rectification and lack of power. However, using a drive with single-phase input and three-phase output, and connecting only the ungrounded power wires, may solve the problem. I am speculating, as no other explanation has been as accurate. The issue does not seem to be with the motor, as it runs on an across-the-line starter without overloads. It appears to be related to the line power.
The issue isn't with the motor as it is operating with an across the line starter without overloads. However, this doesn't rule out the possibility of a partial line-to-line short in the power feeder, leading to intermittent performance. Replacing the wire may be the only solution to this recurring problem.
While it is possible for that to occur, it is important to note that the OP mentioned the second drive was not receiving power before any attempts to use it. This suggests that the issue may be linked to either the drive itself or the power supply connected to it, narrowing down the potential causes of the problem.
If the second drive fails to power up, it may indicate that the output transistors were damaged when power was first applied. For example, in a situation where three drives were installed sequentially, powering each one on resulted in immediate destruction and black-out of the drive HMIs due to a phase-to-phase short at the motor. Neglecting to thoroughly inspect the wiring from the drive to the motor can lead to costly damage to multiple drives over time. Even if you detect 240 volts to ground with a voltmeter, it does not guarantee there is no partial short-circuit present. This type of issue only becomes apparent when current is applied and the damaged insulation on the cables breaks down.
After installing a single-phase input drive, everything is now functioning properly. However, there may still be a damaged leg in use with the new drive, indicating potential trouble ahead in about a year. To prevent future issues, consider the following parameters:
1. Is the power feed from the drive to the motor located underground in a conduit?
2. If so, was the conduit sealed properly during construction to prevent water ingress?
3. Who was present during the cable/wire installation, and was there any incident that could have caused damage to the insulation? By addressing these factors, you can avoid similar problems in the future and ensure optimal performance of your equipment.
In a recent discussion, Lancie1 emphasized that the failure of a second drive to power up could indicate that its output transistors were damaged upon initial power application. Lancie1 shared an experience where three drives were sequentially installed and powered on, leading to immediate destruction and blackout of the drive HMIs due to a phase-to-phase short at the motor. Failing to thoroughly inspect the wiring from the drive to the motor can result in costly damage to multiple drives over time.
It is essential to test for a partial short-circuit by checking for 240 volts to ground with a voltmeter, as some damage may only be revealed when current is applied to expose faulty insulation on the cables. Though the immediate issue may be resolved, there may still be a damaged leg in use with the new 1-phase drive, indicating future trouble ahead.
To prevent further failures, consider the following parameters:
1. Is the power feed from the drive to the motor underground in a conduit?
2. If so, were precautions taken during construction to seal the ends of the conduit to prevent water infiltration?
3. Who oversaw the cable installation process, and was there any incident that could have caused insulation damage?
It is crucial to address potential harmonics on the line side causing capacitive interactions that could increase peak voltage and lead to phase-to-phase leakage. Disconnect and megger the feeder cables individually to detect any leakage to ground or phase-to-phase shorts. Taking comprehensive measures like this will help prevent future issues and ensure the system's reliability.
Greetings, I am currently encountering a similar issue with my VFD PF70 and am in the process of troubleshooting and repairing it. I have already replaced the defective IGBT and attempted to power up the VFD by applying DC voltage to the Bus, but unfortunately, it is still not turning on. I would greatly appreciate any assistance or advice on how to resolve this issue. Thank you.
I noticed that you shared this information elsewhere, and I want to reiterate that it is highly unlikely for a blown IGBT to occur as a standalone event. More often than not, it is just the final straw in a series of issues. It is very probable that the power supply board in the VFD was also affected during the same incident, or even more components were damaged. You may not encounter further problems until after replacing THAT specific board. In my experience, dealing with a blown IGBT is usually not cost-effective because it can lead to a chain of failures, resulting in higher costs and lost production time than simply purchasing a new drive. My recommendation would be to replace the drive altogether, and send the faulty one to Rockwell for rebuilding. If possible, you can then keep it as a spare part for future use.