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Anonymous Poster #1

### GD2 Value of Motor

06/25/2012 1:50 AM

Hi,

Currently we are using 1 Number of 600 Kw motor for Mincer purpose. The GD2 Value of that motor is 215 kgm². Rightnow we are planning to change Fibrizer instead of Mincer. Now the new fibrizer GD2 Value is 59000 kg/m2. What iam exact asking sir , the New GD2 Value is withstand for old 600 Kw Motor or Newly Purchased.

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Guru

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#1

### Re: GD2 Value of Motor

06/25/2012 8:13 AM

Inertia values are not performance related. They are what the device contributes. So the information you presented is meaningless out of context. Start over. What do you have and what do you want to do?

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Anonymous Poster #2
#2

### Re: GD2 Value of Motor

06/25/2012 9:13 AM
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#3

### Re: GD2 Value of Motor

06/25/2012 4:27 PM

JRaef's right, more information needed. Are you trying to re-use the motor?

A few general points.

Are you sure it's GD2, not Mr2 = 1/4*GD2? I ask partly because 215 kgm2 seems very high. ABB data I have for a 630kW 4-pole motor gives Mr2 = 15 kgm2, so GD2 = 60 kgm2. Why use GD2 anyway, it confuses things, all the formulas I can think of use Mr2, you have to put in a 4 somewhere if you use GD2.

The effective load GD2, referred to motor speed, = load GD2*(load rpm/motor rpm)2, so using your 215 GD2 and if, for example, the drive ratio is 16 (speed reducing) the effective GD2 = approx motor GD2.

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#4

### Re: GD2 Value of Motor

06/26/2012 3:00 AM

Net GD2 Value will be GD2 value of the motor plus GD2 value of the load referred to motor shaft . If the overall GD2 value of the system increase then the acceleration time of the motor will also increase due to higher inertia. Starting current will persist for longer duration. Hence motor manufacturer should be consulted to ensure that the rotor is adequately designed for such application.

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#5

### Re: GD2 Value of Motor

07/04/2012 8:09 AM

The revised GD2 indicated is not clear. The GD2 indcates the load of the driven equipment. Hence the incresed GD2 will lead to longer starting time (higher than locked rotor with stand time) because of which the staeencrting current (approx. 6 times full load current) persist for a longer duration. Hence over heating of winding will happen. Hence the motor supplir to be consulted before using for new GD2 application.

R.thiyagarajan

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#6

### Re: GD2 Value of Motor

07/08/2012 11:34 AM

If you are using a slip ring motor it is different.if the motor is cage induction motor gd sq is important.The Mincer GD sq what you mention is reflected in the inverse ratio of gear box in between the mincer and motor.The GD sq of motor is not what matters but load Gd sq + Gear GD sq which reflects on motor.The motor should have a high starting torque and high thermal withstand time.You have to get the T_S curve of the fibrizer and superimpose the motor T-S curve and calculate acceleration time and see whether it is within the thermal withstand time hot which normally is lower.

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#7

### Re: GD2 Value of Motor

07/08/2012 12:05 PM

(inverse ratio of gear box in between the mincer and motor)2. See post #3

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