Siemens 6RA7086-6KS22 Operating Instructions Manual page 449

6ra70 series, microprocessor-based converters from 6kw to 2500kw for variable-speed dc drives, simoreg dc master
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05.05
Fault
No.
Cause as a function of fault value
(r047.001, r949.001 or r949.009 with acknowledged error)
F048
Fault in measuring channel for digital speed sensing using pulse encoder
(active in all operating states)
1. Disturbances on encoder cables:
Faults on the encoder cables (transitions to 0 with a 1 signal or to 1 with a 0 signal) are signalled as a rotational direction change
by the evaluation circuit. Frequent changes in rotational direction can occur only at speeds around 0.
The fault message is activated if 10 consecutive pulse encoder signal evaluations identify "direction of rotation change" at a
speed of ≥ 48 rev/min and an EMF > threshold (see below).
2. Pulse encoder defective:
The fault message is activated if, at an EMF > threshold (see below) 10 consecutive pulse encoder signal evaluations identify
"implausible characteristics" of these signals (i.e. frequent rotational direction changes, edges too close together, failure of an
encoder cable or short circuit between two encoder cables).
Possible fault causes
♦ EMC-related interference on a pulse encoder signal (terminals 28 to 31)
♦ Pulse encoder defective
♦ Interruption in an encoder cable
♦ Short circuit between an encoder cable and the supply voltage or another encoder cable
♦ P110 or P111 is incorrectly set (resulting in incorrectly calculation of EMF)
Note:
When the speed encoder is operating correctly, signal sequences, which are characteristic of a faulty pulse encoder or
disturbances on the pulse encoder cables, may occur continuously at the input terminals (e.g. continuous changes in rotational
direction or short pulse intervals) at about 0 speed, e.g. as the result of slight oscillation around a bright/dark transition on the
speed encoder disk).
For this reason, fault F048 is not activated until the EMF > 10% of
Fault value:
1
Disturbances on encoder cables
2
Defective pulse encoder
10.1.2.8 Start-up faults
F050
Optimization run not possible
(active in all operating states)
A fault has occurred during an optimization run.
NOTE
The contents of r047, Index 002 to 016, can provide specialists with more detailed information about fault causes. For this
reason, please read out and document all the indices associated with this fault and pass them on when you contact Siemens for
help.
Fault value:
Armature current is too low when α=30° and EMF=0.
1
(average armature current <75% of I A, motor or <75% of I A, rated )
Possible cause:
Armature circuit interrupted
High-resistance load
P150 (Alpha G limit) has been set to excessively high value
It was not possible to determine the armature circuit resistance (P110) because the armature current was ≥ 37.5 % of P100
2
in fewer than 20 of the 150 firing cycles of the measuring phase.
Possible cause:
•Armature current of 37.5% of P100 (I A, motor ) is no longer possible (although a current of 75% of P100 was already
flowing, maybe a fuse has blown).
Armature current peaks are too small at α=30° and EMF=0
3
(armature current peak value <50% of I A, motor or <50% of I A,rated )
Possible cause:
Armature circuit inductance is too high (field supply from armature terminals)
P150 (Alpha G limit) has been set to excessively high value
Possible remedy:
Reduce P100 (I A,motor ) while this optimization run is in progress
SIEMENS AG
6RX1700-0AD76
SIMOREG DC Master
Operating Instructions
Description
Further information (r047.002 to r047.016)
3
2
P078.001
π
Faults / Alarms
.
10-13

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