Up Size Motor

9800→9900 = amusing increment. What does the catalog say?

This increase in load seems to be a small percentage. I feel the cable can sustain. But not sure about it.

Revisit the cable sizing calculation that was used to select the cable in the first place, and reassess it using the new figures.

Is a ~1% increase in motor power significant compared to the expected variation in voltage of the supply, which is likely to be larger than this? Would it be better to do things to the pipeline to reduce flow friction instead? Would it be better to make process alterations that avoid an increase in motor size? What is this motor driving? If it is a pump, re-assess the operating point on the performance curve. Would cleaning the pump and the pipe, or reducing the delivery head in other ways yield a better operation? Would changes in the way the pump is used overcome the operational difficulties?

And the recommendation on the cable size is.......

Suitable !

This is such a small percentage change in power

(9900-9800)KW/(9800KW)*100%≈1.02%

that the entire increase in shaft power could be due to motor design improvements. So I would not be surprised if this new motor could just be used without modification. A qualified engineer/electrician should inspect, review and possibly bless the installation since none of the real critical factors has been offered here.

"...Due to the process problem the motor operate at 100% all time..." Sounds to me like the answer probably lies in the process, not the motor. Increasing the motor size will likely result in it running at 100% after some period of time unless the root cause of the process requiring more power than it was originally designed for. Do a complete review and determine what has changed before you blindly replace the motor.

What is the process problem that has increased the power demand to 100%?This problem needs to be addressed first.If it is a result of an expansion or addition to the process, then to safely upgrade, you need at least 25% overhead margin.

1% is insignificant, and you may find that your process will absorb this small amount at times, so you will be no better off that you are now.

Analyse the original process,compare to original specifications, determine what has changed.

You may find your current problem is an issue caused by maintenance issues,such as bearings,valves,or wear internal to the compressor or motor.

I do not know what you are compressing, but if it a refrigerant or other condensible media, you may have some non-condensible gases entering the system thru small leaks on suction side.Compare discharge pressure and temperature to determine if this is the problem.Pressure will be higher than chart listing if this is the case.

You do not provide enough information for any detailed advice.

As for cable sizing, that question was answered very knowledgeably by a previous reply.

Good Luck

Really? You think that our OP is capable of doing a true, methodical analysis of an electrically powered mechanical system, I don't. I think the OP was looking for a motor equivalent of the Windows three finger salute to return to normal.

In the first place I seriously doubt that this motor is actually running at 100%. Remember our OP stated "during the heavy rain fall and cause the motor load increases more than 100%". Depending on how one chooses to disentangle this near translation to English, one could expect either an over unity condition or a stalled motor. Don't get me wrong, I'm certain the OP believes that the motor works at 100% because the current times the voltage tells them so. I doubt the OP has any understanding of phase angles between current and voltage and the difference between real and reactive power.

Reply from Loher (OEM) recommend the new motor rating is 1100KW at 6.6KV and the full load current is 105 Amp and power factor is 0.92, I still awaiting for the final confirmation from Loher about the motor frame size and specification must be same at the exciting motor setup to avoid the majors modification work of the exciting compressor & electrical setup.

Now it is clear. It is 980kW not 9800kW. So, the the ampere 96.5 at 0.9 pf is seems right. I was little confused about the ratings.

Now, with these up sizing of motor to 1100kW makes your operation at 90% full load capacity. Since the suggestion is from Loher , this is ok. But the process is yours. I will suggest to go 1300kW so that the percentage loading on motor will be 75% of full load. This will make your process and motor stress & stain free.

I would suggest you obtain complete specifications from the motor manufacturer.

Some motors maintain high efficiency when loaded below full rating, but most tend to drop off,especially around the 75% area.New high efficiency motors are designed to maintain high efficiency through a broader load range, so it would pay to check on this option.It may be possible to recoup some of the upgrade costs through energy savings., and you may find that it is even cheaper to operate the larger motor than the smaller old one,especially if it is of an older less efficient design.

I am sure the motor manufacturer would make these calculations for you if you asked.