NORD Drivesystems BU0510 - Manual (Page 72)

POSICON position control for NORD frequency inverters, SK 530E and above
72 Subject to technical alterations BU 0510 GB-3911
7.2 Troubleshooting table
The following table contains the most frequent sources of faults and the associated symptoms. It is
recommended that the same sequence as for commissioning is used for troubleshooting. I.e. first check if the
axis runs without control and then test the speed and position controls.
7.2.1 Sources of faults in servo mode operation (without position control)
Symptom Additional test Possible cause
Motor only runs slowly,
motor vibrates
Change sign in P301

incorrect assignment of motor direction to the
incremental encoder direction

Incorrect incremental encoder type (no RS422
outputs)

Encoder cable broken
(Voltage difference between track A and B
cannot be checked with P709)

Encoder voltage supply missing

Incorrect pulse number parameterised

Incorrect motor parameters

Encoder track missing
Motor rotates correctly, but vibrates
at low speeds
Switch-off of overcurrent at higher
speeds
Problem disappears when
the servo mode is switched
off

Incremental encoder incorrectly mounted

Interference in encoder signals
Overcurrent switch-off when
braking Motor in field weakening
operation

For field weakening operation in servo mode, the
torque limit must not exceed 200%
7.2.2 General sources of error with positioning control enabled
Symptom Additional test Possible cause
Position exceeded 
Position control P amplification considerably too
large
Speed control (servo mode) not optimally
adjusted (Set I-amp. to approx. 3%/ms, P-amp.
to approx. 120%)
Drive oscillates at the position

Position control P amplification considerably too
large
Drive moves in the wrong direction
(away from the setpoint position) 
The direction of rotation of the absolute encoder
does not match the direction of rotation of the
motor => parameterise an negative value for the
speed ratio (P607)
Drive unit sags away after enabling
is removed (lifting gear) 
Setpoint delay missing (control parameter)

for servo mode = "OFF" the control must be
locked immediately by the event "End Point
Reached"