It's more a question about electricity not electronics, but anyway:
My 3 phase kilowatt-hour meter is labeled 10(60)A. If I understand correctly, 10A is basic current and 60A is maximum current, but what does that actually mean? Can I apply more than 10A per phase? For how long?
You should check the spec's on the manufacturers data sheet for the unit. That's the only way to know for sure. They designed it and only they can know for sure.