Allen-Bradley 1407-CGCM, User Manual, Page: 194 / 252

Rockwell Automation Publication 1407-UM001H-EN-P - November 2014
!PPENDIX" CGCM Unit Math Models
3OFT3TART#ONTROL
The soft start control function is provided to cause orderly build-up of terminal
voltage from the residual voltage to the rated voltage in desired time with
minimal overshoot. In CGCM units, the fast dynamic response is used while the
voltage reference is adjusted based on the elapsed time. When the system is under
start-up condition, the voltage reference is adjusted by the amount calculated
based on two programmable parameters, initial soft start voltage level (V
O
) and
desired time (T
SS
) to build up to the rated voltage. Its mathematical model is
shown in Soft Start Control. The soft start gain (K
SS
) is calculated by using this
formula.
K
SS
= (V
REF
- V
O
) / T
SS
&IGURE3OFT3TART#ONTROL
Time From Start
AVR
Summing
Point