How can I fix my hotpoint Aquarius tumble dryer?

The dryer comes on for about twenty minutes and it trips the circuit breaker we turn it back on again and it trips after about ten minutes. We cleaned all the filters, took off the back and cleaned around the element, gave it a thorough clean and replaced the relay and its still tripping the circuit. It seems the warmer it gets it trips quicker. Can anyone advise what the problem might be?