E3— Overvoltage when shutdown

(the bus voltage is greater than 450v for 3 second when shutdown)

Steps:
Check whether the inlet voltage of control box is stable, if it’s within the specified range of 200V-250V
when standby, enter monitoring interface of operation control box and see what’s the voltage appear in UDC interface, then run the motor to see how much voltage rise while scram(usually around 410V)[the inlet voltage multiplied by 1.41 = interface voltage]
if the voltage showed in UDC is wrong, using Isolation transformer with 80V to supply  power, then detect the both ends voltage of + /- control board’s rectifier bridge: inlet voltage multiplied by 1.41; C73 ends impedance: around12.5K; Two terminal voltage (means pin3 to pin4 safety line of U9): around 0.56V
if the voltage showed in UDC is wrong, using Isolation transformer with 80V to supply  power, then see impedance of R143 of main control board: 100Ω; C77 Two terminal impedance: around 3.3m; Two terminal voltage (means pin1 to pin4 safety line of U9): around 0.56V.