Rockwell Automation 20D PowerFlex 700S with Phase I Control Reference Manual - Manual (Page 53)

Rockwell Automation Publication PFLEX-RM002D-EN-E - August 2013 53
Detail Drive Configuration and Operation Chapter 1
Droop Droop is used to “shed” load and is usually used when a soft coupling of two
motors is present in an application. The master drive speed regulates and the
follower uses droop so it does not “fight” the master. The input to the droop
block comes from the torque output of the speed regulator before limiting. The
output of the droop block reduces the speed reference. Parameter 86
[Spd Reg Droop] sets the amount of base motor speed that the speed reference is
reduced when at full load torque. [Spd Reg Droop] is in units of per unit torque/
per unit speed. For example, when [Spd Reg Droop] is set to 0.1 and the drive is
running at 100% rated motor torque, the droop block would subtract 10% from
the speed reference.
Dynamic Braking See Bus Regulation/Braking on page 20 .
This module contains a second order thermal model of the internal. For resistor
sizing, refer to the PowerFlex Dynamic Braking Resistor Calculator Selection
Guide, publication
PFLEX-AT001 .
Efficiency The following chart shows typical efficiency for PWM variable frequency drives,
regardless of size. Drives are most efficient at full load and full speed.
Electronic Gearing See Position Loop - Follower (Electronic Gearing) on page 82 .
86
Droop
Spd Reg Droop
10 20 30 40 50 60 70 80 90 100
% Speed/% Load
% Efficiency
vs. Speed
vs. Load
75
80
85
90
95
100