Low voltage can only be two things: The grid is feeding you lower than usual voltage, or you have some resistance in series with the outlet that is dropping voltage as heat when you draw power.
There’s a lot of well-meaning but dangerous advice in this thread. Low voltage at a receptacle under load, or not, can be caused by several issues, not just low "grid" supply or series resistance. A lifted neutral, shared neutral fault, or ground fault, or other serious issues are all possibilities.
None of you, save Paul B, myself or a few others on this forum have the knowledge, experience or qualifications to troubleshoot this issue. I can't speak for Paul or the others, but there are too many possible issues here to diagnose over the internet, when the OP has the ability and means to call a qualified electrician.
This isn’t a nuisance trip. The OP has moved equipment on and off the circuit, and the breaker still trips. That means there’s an overload, a fault, or a failed breaker. The trips may be the result of the low voltage, but guessing the root cause over the internet is dangerous, as is repeatedly resetting the breaker. Full stop.
Unless the OP is in a remote camp without access to a qualified electrician, this simply isn't something to troubleshoot over the internet. A person with has stated twice that he has no electrical knowledge, has no business poking around with a meter or diagnosing this type of issue based on random forum advice. It is serious safety risk.
No offense meant to anybody here, I understand everyone is trying to help in good faith. In situations like this, it is best left to a local hands-on expert.
Edited - for clarity. Not trying to offend anybody.