If it trips a small breaker on the board then it has a fault of taking too much current - if it trips a larger breaker that disconnects several circuits then it probably has an earth leakage fault.
In either case it needs specialist attention - at 7 years old you might consider replacing it rather than a repair.
The fault may well be a heating element - can you run it on zero heat - cold - as a diagnostic?
Good luck...
Ella Fitzgerald, September 2014
