Ok theres 2 things that causes this either the motor or the wash heater.
What you need to do is pull the washer out and remove the back and make sure its unplugged.
There you will see the motor at the bottom under the drum.
Disconnect the wiring block on the motor then turn it back on and see if it stops the tripping.
If it does then we know its the motor at fault and the motor will need to be replaced.
But if its not the motor then on the back at the back of the drum you will see the heater.
Disconnect the wires on there and do the same and turn it back on and see if it stops the tripping.
If so then the heater needs to be replaced.
But if after that its still the same then try and cut the plug top off and replace it with a new plug and see if this works. As a few times ive had it were its the plug top itself shorting out.
Try that and see how it goes as for tripping the rcd its usually one of them that causes it.