Hello, I am currently experiencing vibration issues with a 27-ton generator rotor running at 3600 rpm. The vibrations at the 1500 rpm/1st critical speed are at 10 mm/s rms, while at the 2700 rpm/2nd critical speed they are at 19mm/s rms. The vibration levels at the NDE V side are at 10 mm/s, and at the DE V side they are at 4 mm/s during the 1st critical speed. The vibrations are higher on the NDE side compared to the DE side. The spectrum analysis shows that the vibrations are predominantly at the 1x peak, indicating an unbalanced rotor. Can anyone provide advice on how to balance this rotor in order to achieve optimal performance at full speed? Thank you.
Greetings! Have you conducted start-up and coast-down tests for your generator? An increase in the 1x order in the spectrum may be due to unbalance, structural looseness, or resonance. Make sure to address these issues to ensure optimal performance. Best regards.
Based on the information you've provided, it indeed seems like unbalance is causing the excessive vibrations. My suggestion would be to perform a field balancing operation. This basically involves adding small weights to the rotor in the appropriate places to counteract the imbalances. The steps usually are to firstly measure the current state of vibration, then add a trial weight in a chosen position. Measure the change this brings about, which then informs the correct weight and its position to minimize vibrations. Of course, you'll need the right equipment and possibly a skilled technician for this. Consider engaging a professional balancing service if you haven't done this before.
I recommend looking into dynamic balancing for your generator rotor. It's a process where the rotor is spun at a high speed in a balancing machine outfitted with sensors to detect areas of imbalance. Since the analysis shows vibrations at the 1x peak, it's a strong sign of rotor imbalance. By adjusting the mass and distribution on the rotor to correct for these imbalances, you can significantly reduce the vibrations. Keep in mind, the procedure should be carried out by a qualified professional to ensure safety and accuracy. Also, ensure that your rotor's assembly is checked - things like bearing alignment or faulty couplings can also contribute to imbalances.
It sounds like you're dealing with quite a challenging situation! Given the vibration levels, it’s crucial to confirm that the rotor is indeed unbalanced before proceeding with the balancing. Make sure to conduct a thorough analysis to pinpoint the imbalance location and magnitude. You might want to start with a trial weight adjustment or dynamic balancing method if you haven’t done so already. Sometimes, using a balancing machine can provide precise insights on how much weight to add or remove. Also, don't forget to check for any misalignments or mechanical issues that could be contributing to the vibrations. Good luck, and I hope you get the rotor running smoothly soon!
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Answer: - Common symptoms of an unbalanced rotor in a generator include increased vibrations, particularly at specific critical speeds, as well as uneven vibration levels between the non-drive end (NDE) and drive end (DE) sides.
Answer: - The critical speeds of a generator rotor can be determined through vibration analysis, where significant increases in vibration levels occur at specific rotational speeds.
Answer: - Balancing a generator rotor is crucial for reducing vibrations, minimizing wear and tear on components, and ensuring smooth operation at full speed, ultimately enhancing the overall performance and longevity of the equipment.
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