I assume you mean 'the maximum inertia that a motor is capable of handling'.
You need to think instead of the inertia ratio (IR)
IR = Jl/Jr
Jl = 'reflected' load inertia, what is the motor coupled to.
Jr = motor rotor inertia, found in any motor description
Here's my rule of thumb for a...
Look at www.beckhoff.com for PC package that is pure 1131 (IEC 61131-3 to be exact), they have all the hardware as well. You can do all your motion (even CNC) here as well.
You are on your own for a HMI though. I will say that getting the two linked up can be very easy if you approach things...
Rather than get all scientific and throw a bunch of formulas around, think of it this way...
Once power is removed that motor is now a generator.
That generator is NOT going to be synchronized with the power system.
When power is reapplied while the motor(now generator) is still spinning you...
Take a gander at www.beckhoff.com
Lot's of I/O, PC-based, pretty easy to set up and get talking to even the most pesky fieldbus. I prefer the Ethernet versions to all as long as real-time is not needed. Even then it is doable if done right.
Robert Trask, PE
Los Angeles, CA
www.beckhoffautomation.com
Has the best 1131 stuff I've seen. And it does motion too.
FBD's rule for doing motion by the way...
Robert Trask, PE
Los Angeles, CA