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Selection Of Generator For A Corrugator Plant


AB2005

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Hi;

 

We are planning to install a standby Genset for our Corrugator plant. The connected load is 1740KW and the net power factor is almost 0.58. The running peak load 525KW has been recorded up to now @ PF 0.58. So the total apparent power demand of load is 905KVA @ 400V & pf-0.58. So according to me, the 1.2Mva Genset would be sufficient. What is your openion?

"Don't assume any thing, always check/ask and clear yourself".

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Hello AB2005

 

What at the peak loads due to motor starting and also the harmonics due to VFDs??

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What is the largest motor that you start on this machine and how is it started?

Are there AC and/or DC drives and what size?

 

Best regards,

Mark.

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The largest motor is DC 218KW with its DC drive. The corrugator machine has all DC drives. However, we have following big motors which starts on Star Delta;

 

  1. 50KW 02nos
  2. 37KW 02nos
  3. 22KW 05nos
  4. 15KW 04nos.

Others are small (<15KW) AC DC motors. SOme of them start with DC/AC drives and some one on star delta or direct delta. We have total 615motors big and small.

"Don't assume any thing, always check/ask and clear yourself".

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Hello AB2005

 

With the number of DC drives that you have, you will have major harmonic currents which could cause issues with the generator and other connected load.

I would strongly recommend that you use a three phase averaging AVR and permanent magnet generator excitation.

From the information given, the size may not be an issue, but harmonic voltages may be due to the harmonic currents and the reactance of the generator.

If any of the DC drives are 4 quadrant with regenerative braking, you may have issues.

I would suggest that a) the generator supplier should be able to advise you, and B) in the absence of further information, you will need to try it and see.

 

Best regards,

Mark.

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  • 2 months later...

I installed a 1275kva rental genset during a power shutdown period and found no any issue with its operation with running all machines but max load was recorded on it was

one problem i observed that while generator was in operation, the Nokian PF relay was switched on the required capacitors and after few minutes, it switched off the all capacitors and then again switched on step by step. That cycle was repeating again and again.

Some time same happens with utility power but after cycle the power of Nokian PF relay, it become normal but with generator in-operation case, it did not go to normal after cycled its power.

"Don't assume any thing, always check/ask and clear yourself".

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Hello AB2005

 

The reactive impedance of the supply is potentially much higher on the generator supply than on the main supply and so the harmonic voltages could be higher and resulting harmonic currents through the capacitors can also be a problem.

 

Additionally, a high capacitive loading can cause issues with the AVR on the generator and this could also cause the instability.

 

Best regards,

Mark.

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