[Crex]

Power strips tend to get "worn-out" sensitive and start tripping at lower amperage draw (not all but many). Sounds like yours has gotten sensitive. The "Monster" comes in several configurations some are more shop worthy than others.

That aside, I have always found it better to have big draw items like grinders etc direct plugged to service receptacles and not through a power strip of any kind. You could eliminate the power strip and plug directly to a recp. and see if the problem continues to occur. If so, you have a surge problem with your drive/motor and need to have it checked out. If you have to use an extension cord, keep it short as possible and use good heavy duty one. Run your grinder awhile then feel the cord and it's connectors at both ends. They will probably be warm but shouldn't be hot. If hot, again get help.

Another possibility is if you have more than one item plugged in to the power strip and more than one thing running you might be exceeding the 15 amp surge at some point tripping it's on board breaker.
Also check the amperage rating on your motor tag just to make sure it's not higher than any of your in-line breakers ie. - power strip and main breaker for recep.