Siemens MICROMASTER 440 Operating Instructions Manual page 180

3 Functions
Droop (P1488 – P1492)
The droop (enabled using P1488) means that with increasing load torque, the
speed setpoint is proportionally reduced.
Droop
P1492
Freq. setpoint
Act. frequency
*) only active if the pre-control is activated
(P1496 > 0)
Fig. 3-82
Droop is the simplest method to implement load sharing control. However, this load
sharing control can only be used if the drives only motor and are operated more or
less under steady-state conditions (i.e. at constant speed). For drives, which are
frequently accelerated and braked with high speed changes, this technique is only
conditionally suitable.
The most simple load sharing control is, e.g., used for applications where two or
several motors are mechanically coupled or operate on a common shaft and which
have to fulfill the requirements above. In this case, the droop controls torsional
stressing associated with the mechanical coupling by changing the speeds of the
individual motors (excessive torques are reduced for an individual drive).
Prerequisite
All of the drives must be operated with closed-loop Vector speed control (with or
without speed actual value encoder)
The ramp-up and ramp-down times of the ramp-function generator must be
identical for all of the drives.
180
150 ms
r1490
0
0
Pre-
control
–
*)
T
i
Speed controller with droop
0
0
1
2
3
K
T
p
n
r1538
PI
r1538
Speed
r1539
controller
–
r1539
T
SLVC: P1452
VC: P1442
MICROMASTER 440
Issue 10/03
r1482
r1538
Torque
r1539
setpoint
K T
p n
i
P1470 P1472
P1460 P1462
Operating Instructions
6SE6400-5AW00-0BP0