Siemens SINAMICS CU240S DP-F Operating Instructions Manual page 106

Commissioning
5.8 Commissioning the Encoder
Parameter Name
Comment
P0492[3] Allowed speed difference
This parameter defines the frequency threshold for the loss of the encoder signal (fault F0090). The
threshold is used both for low as well as also high frequencies.
1. Signal loss at high frequencies:
Fault F0090 is output if the actual frequency and the frequency difference between two sampling
periods (t_A) is greater than that specified in parameter p0492:
(actual frequency f_act > p0492 and f(t_A2) - f(t_A1) > p0492)
Note
A fixed delay time of 40 ms is stored in the frequency converter. Fault F0090 is only activated when
the encoder signal is lost at a high frequency after this delay time has expired.
2. Signal loss at low frequencies:
Fault F0090 is output if all of the conditions for case 1 or case 2 are simultaneously fulfilled:
Case 1
–
–
–
Case 2
-
-
Inter-dependency
This parameter is updated after the motor starting time p0345 has been changed or the speed was
optimized (p1960 = 1).
Caution
p0492 = 0 (no monitoring function):
With p0492 = 0, the loss of the encoder signal at high frequency as well as at a low frequency is de-
activated. As a result, the system does not monitor for the loss of the encoder signal.
If the encoder signal loss is de-activated and the fault occurs, then the closed-loop motor control can
become unstable
P0494[3] Delay speed loss reaction
Used for low speed encoder loss detection.
If the motor shaft speed is less than the value in P0492 then encoder loss is detected using a low
speed encoder loss detection algorithm. This parameter selects the delay between loss of encoder at
low speed and reaction to the encoder loss. (Default = Calculated from inertia, Range from 0 to
64.000s).
Dependency: This parameter is updated when P0345 Motor start-up time is changed or when a speed-
loop optimization is performed (P1960 = 1).
Caution: When this delay is set to 0, then low speed encoder loss detection is disabled and low speed
encoder loss cannot be detected (high speed encoder loss detection will still operate if P0492 > 0). If
low speed encoder loss detection is disabled and encoder should be lost at low speed, then operation
of motor may become unstable.
P1300 Control Mode
21: Closed loop speed control
23: Closed loop torque control
106
actual frequency < p0492
r0061 = 0 and the torque is limited
r0061 = 0 with setpoint frequency f_set > 0 for a time > p0494
actual frequency < p0492
f(t_A2) < p0492 and a fault is detected in channel B
Operating Instructions, 07/2008 - FW 3.2, A5E00766042B AD
Control Units CU240S