viair hookup

got a viair 550. Before i had a traditional solenoid with a normal pressure switch with a 450. With the new 550 i kept the old solenoid in conjunction with the 550 relay and its burning up solenoids quickly and I have replaced several. Do i eliminate solenoid all together and just use relay that came with 550 instead? Does anyone know how to wire 550 relay? THANKS!