GD2 Value of Motor

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?

http://en.wikipedia.org/wiki/Moment_of_inertia

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.

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.

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

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.

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

As exactly said ,

For Fibrizer one has to go with slip ring induction motor ...incase if you are going with slip ring motor , it can take additional load due to the extra GD2 Value.

incase you are going with slip ring motor , it doesn't matter whats ur fibrizer GD2 value...

only thing is u have to select proper roter resistance starters.

Dear Friend,

You have to provide the GD^2 value of the Mincer.

What I understand from your posting is that GD^2 of 215 Kg.M^2 is that of the Rotor of the Motor. The GD^2 value for the Mincer will be higher than that of 215 Kg.M^2, and the Fibrizer GD^2 is equal to that of the Mincer - there won't be a problem in starting the Fibrizer. If it is more, then there will be starting problem. If it is marginally high, Auto Slip Regulating Starter will be helpful to start.

DHAYANANDHAN.S

Dear sir,

Thanks for your valuable reply message.

Vikash