undervoltage trip.

dear all

i have one terasaki ARU23 D undervoltage trip unit.but i dont know how it works..and it has 5 terminals two for input ie 230 v ac,and 3 for out put ,i am getting an out put value of 50 v dc .how can i check whether it is working properly or not.and also i need the information regarding with how it works with braker.. the breaker now getting closed.when i am giving over load the the breaker is not getting trip that means my uvt is not working correctly..how can i check ...please help as soon as possible....