Do you seek to know how an RCD trips or what might be wrong with the dishwasher?
An RCD compares current in the Live and Neutral lines - if there's a difference it assumes the missing current to be running to earth and possibly through a person - it's a safety device to prevent electrocution.
Appliances with heating elements often develop a fault in the element - the live resistance wire touches the outer case causing a short to earth - if there's an RCD in the circuit it will trip.
It's by no means certain but there's a very strong probability that your machine has a defective heating element.
I can say no more..., December 2015
