Hello, I am seeking advice on a new electronic governor we are testing for our DG set. We are using the Woodward APECS DPG-2201-00X Digital controller, and we have noticed that the steady state speed of the DG is fluctuating by approximately + or - 3 rpm (rated speed of 1500 rpm) under all loads. According to the governor specifications, the steady state speed band should be within + or - 0.25%. I am wondering if this fluctuation is within acceptable limits, or if further fine-tuning of the controller is needed. Can you help me interpret the specification of steady state speed and determine if our governor is performing satisfactorily? Thank you for your advice.
Have you considered reaching out to Woodward? Check out their website for more information: http://www.woodward.com/pdf/ic/36503.pdf.
When calculating the speed variation of a generator operating at 1500 rpm, 0.25% equates to 3.75 rpm. While this may seem acceptable, it falls short of the observed fluctuation of 3 rpm. It is important to ensure that the generator can maintain a consistent speed under load. To verify accuracy, consider using a second tachometer. Additionally, it is advisable to consult with engine, generator, and control vendors to address any speed variation concerns. - Walt
Hello Josh and Walt, we have noticed fluctuations at both 75% load and 100% load (rated at 350 kW). Our requirement was to have maximum allowable fluctuations of +/- 0.75 rpm at steady state, but what we are seeing is around +/-3.0 rpm. The Woodward representative has mentioned that this is the best they can achieve. Is there a way to further improve this situation?
During the trials, the rotations per minute (rpm) were measured using the frequency output produced by the alternator and by tapping into the digital frequency meter. Following your recommendation, I will attempt to utilize an alternative frequency meter for more accurate measurements.
For troubleshooting, consider reviewing the setup and parameters at http://www.roadtec.com/Service/documents/rexroth_genera...20speed%20variation'.
Based on the steady state speed band specified by the manufacturer (+ or - 0.25% of rated speed), the acceptable fluctuation range at a rated speed of 1500rpm should be within + or - 3.75rpm. Given that your DG set is fluctuating only by + or - 3rpm, it's actually within acceptable limits. So, it looks like your governor is performing on par, if not slightly better than the manufacturer's specifications. But, if you're constantly pushing heavy loads it might be beneficial to fine-tune to get closer to the 1500rpm rate for optimum performance. Keep up with maintenance and happy regulating!
Hello, your situation seems interesting. I'm no expert but I did some basic math just to give some insight. With a rated speed of 1500 rpm, a variation of + or - 0.25% corresponds to a fluctuation of + or - 3.75 rpm. The fluctuation you're experiencing (+ or - 3 rpm) is less than the specified band. So, it seems like your DG set is operating within the acceptable limits. However, seeing as the fluctuation is so close to the specified limit, you might want to look into fine-tuning your controller to ensure the fluctuation stays within acceptable limits under various operational conditions.
The ±0.25% steady-state speed you're referring to actually means it should maintain the rated speed within a band of ±3.75 rpm (0.0025*1500) for a 1500 rpm rated speed. If your observed fluctuation is ±3 rpm, the controller is indeed performing within its specifications and there's no need to further fine-tune it. Keep in mind though, various external factors such as machine ageing, temperature changes, and load fluctuation can also affect the speed, so keep an eye on those as well.
Hello! It's really a matter of simple math here. Given a rated speed of 1500 rpm, a +/- 0.25% variation would lead to a speed deviation of approximately +/- 3.75 rpm. Thus, if your DG set's speeds are fluctuating by +/- 3 rpm, it falls within the acceptable limit defined by the governor specifications. There could be a minor tuning adjustment to be done if you wish to get it closer to the nominal value, but as it stands, it seems your governor is performing within satisfactory limits.
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Answer: - According to the governor specifications, the steady state speed band should be within + or - 0.25%.
Answer: - No, the observed fluctuation of + or - 3 rpm exceeds the specified steady state speed band of + or - 0.25%.
Answer: - Yes, further fine-tuning of the controller may be necessary to bring the speed fluctuation within the acceptable range specified by the governor.
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