Setting The Rotor Contactor Stepping - Siemens SIMOTRAS 6SG7050 Operating Instructions Manual

01.04

7.6.15 Setting the rotor contactor stepping

Specifying limit values for switching over the rotor contactors (see Section 3.3.6 and 3.3.7):
On every control characteristic curve (in other words at a particular rotor resistance), the maximum
possible torque reduces as the speed increases. As a result, the converter switches to the next
rotor stage at the speed where the maximum possible torque is just 100% in order to receive an
appropriate acceleration torque (switchover points S2, S3 and S4 in Fig. 7.6.15.1)
see also Section 6.1 Block diagram
n
%
100
80
60
40
20
0
0 20
-20
-40
-60
-80
-100
Fig. 7.6.15.1
• with increasing speed:
U634 Value at which the rotor contactor for stage 2 is to be connected
U636 Value at which the rotor contactor for stage 3 is to be connected
U638 Value at which the rotor contactor for stage 4 is to be connected
• with decreasing speed:
U638 (– U639 hysteresis)
Value at which the rotor contactor for stage 4 is to be disconnected
U636 (– U637 hysteresis)
Value at which the rotor contactor for stage 3 is to be disconnected
U634 (– U635 hysteresis)
Value at which the rotor contactor for stage 2 is to be disconnected
SIEMENS AG 6SG7000-0BA76
SIMOTRAS HD Operating Instructions
Full load curve
Lift
100
40 60 80
Full load curve
Lower
Rotor contactor switching cycle
Switch over to next
torque characteristic
Switchover point
S4 S3 S2
120 140 160 180
Mzus.
Switchover point S1a
(see Section 7.6.16)
Current limit
Activation of
rotor contactors:
Stage 4
Stage 3
Stage` 2
Stage 1
(Start-up stage)
%
M
Switchover point S1b
(see Section 7.6.16)
Y
Counter-torque stage
Start-up
7-17