About the moment of inertia
About the moment of inertia
(OP)
Could anybody tell me what is the exact meaning of load moment of inertia? And what is the weighting factor?
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
About the moment of inertia
|
RE: About the moment of inertia
RE: About the moment of inertia
RE: About the moment of inertia
RE: About the moment of inertia
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: About the moment of inertia
electricpete; What about those UPSs that hold up the load on this kinetic energy alone while the prime mover is started?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: About the moment of inertia
1A- The motor power factor during start is very low. It demands a lot of reactive power. Reactive power depends primarily on voltage.
1B - The inertia assists the generator to supply real power. This real power helps to keep the frequency up.
2 - The presence of larger inertia means that the frequency will not droop as much during start. It doesn't tell us anything about the voltage.
3A - The torque developed in the motor during start depends primarily on the voltage (varies roughly as square of voltage).
3B - The torque developed in motor during start depends to lesser extent on frequency.
For a typical system, I believe the fractional variation in voltage will be much higher than the fractional variation in frequency. And the motor torque is more sensitive to voltage variation than frequency variation to begin with (item 3).
So the challenge during start is to keep the voltage up to help the motor start fast. The inertia does not particularly help with this aspect.
Again, just my view. I don't get involved in design activities or operating generators in island mode. If my logic is incorrect, I'd be interested to hear.
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: About the moment of inertia
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: About the moment of inertia