4–6

Optional Controlled Decel and Alarm at Power Loss

Operations and Monitoring

The timing diagram below shows a power loss scenario and the related parameter settings. During the controlled deceleration the inverter itself acts as a load to decelerate the motor. With either a high-inertia load or a short deceleration time (or both), it is possible that the inverter impedance will not be low enough to continue linear deceleration and avoid an over-voltage condition on the DC bus. Use parameter B052 to specify a threshold for the over-voltage. In this case, the inverter pauses deceleration (runs at constant speed). When the DC bus decays again below the threshold, linear deceleration resumes. The pause/resume process will repeat as necessary until the DC bus energy is depleted (under-voltage condition occurs).

DC bus (V)

 

B052

 

B051

 

Under-voltage

 

level

 

0

t

 

Output

B054

Frequency

B053

0

 

 

 

t

NOTE: (1) Be sure to set the over-voltage threshold greater than the DC bus voltage trigger level (B052 > B051) for proper operation.

(2)Once the power loss deceleration function starts, it will complete and stop the motor even if input power is restored. In that case, it automatically enables the Run mode again.