Siemens Sinamics S120 Function Manual page 164

Vector control
4.7 Open actual speed value
Interconnection of p1440:
When interconnecting connector input p1440 with an external actual speed value, ensure the
speed scaling is the same (p2000).
The external speed signal should correspond to the average speed of the motor encoder
(r0061).
Behavior for speed control without an encoder (p1300 = 20)
Depending on the transmission path of the external speed signal, dead times will occur;
these dead times must be taken into account in the speed controller's parameter assignment
(p1470, p1472) and can lead to corresponding losses in the dynamic performance.
Signal transmission times must therefore be minimized.
p1750.2 = 1 should be set so that the speed controller is also able to work at standstill
(closed-loop controlled operation to zero frequency for passive loads). Otherwise, at low
speeds it switches over to speed-controlled operation, so that the speed controller is
switched off and the measured actual speed no longer has an influence.
Monitoring of the speed deviation between motor model and external speed
The external actual speed (r1443) is compared with the actual speed of the motor model
(r2169). If the deviation is greater than the tolerance threshold set in p3236, after the switch-
off delay time set in p3238 expires, fault F07937 (Drive: Speed deviation motor model to
external speed) is generated and the drive switched-off corresponding to the set response
(factory setting: OFF2).
Figure 4-13
Function diagrams (see SINAMICS S120/S150 List Manual)
● FP 6040 Vector control – Speed controller with/without encoder
● FP 8012 Signals and monitoring function – Torque messages, motor locked/stalled
Overview of important parameters (see SINAMICS S120/S150 List Manual)
● r0063[0...2] Speed actual value
● p1440 CI: Speed controller actual speed value
● p1443 CO: Actual speed value at speed controller actual speed value input
162
Monitoring "Speed deviation model / external in tolerance"
Function Manual, (FH1), 01/2012, 6SL3097-4AB00-0BP2
Drive functions