Applications
Servo drives operated in speed control or position control mode.
a) Applications in which a specific speed following response is supposed to be adhered to
b) Extended monitoring option of the actual speed value encoder.
to a)
The function allows the evaluation of the speed following behaviour of the drive controller. If the deviation at the speed controller exceeds the value tolerated under C0576 there may be an error at the drive as well as in the process of the application.
The evaluation of the nErr speed monitoring gives e. g. information about the process-depending mechanical blockades in the application. During production the drive can be monitored by the superimposed control. During commissioning the setpoint / quick stop ramps can consequently be adapted to the application.
to b)
In addition to the encoder monitoring Sdx the drive controller can be made more reliable by the nErr speed monitoring. Many errors of the encoder systems have the effect that the actual speed value cannot be generated correctly. Usually, this leads to a speed controller's system deviation higher than in normal operating state (set tolerance value).
The evaluation of the nErr speed monitoring can also be used as a general monitoring function for the connected encoder systems. The function does not depend on the applied encoder type.
Function description
The monitoring function of the feedback system connected to terminals X7 and X8 of the controller has been extended by malfunction monitoring.
The actual speed detected by the feedback system is compared to the speed setpoint of the speed controller.
If the difference of the signals is outside the window selected under code C0576, the error message 'nErr' will be displayed under C0168.
The error response can be configured as 'TRIP', 'MESSAGE', 'WARNING' and 'OFF' via code C0579. In the default setting the function is deactivated when being set to 'OFF' due to the compatibility to be adhered to with older versions.
A tolerance (0 - 100 % related to n-max in C0011) can be set under code C0576 in order to fix a speed difference between actual value and setpoint which is permissible for the application.
In the function block MONIT a signal output MONIT-SD8 was added.
Attention
When using synchronous machines it is essential to set the error response 'TRIP'.
Additional safety is ensured by the combination of the nErr speed monitoring with the P03 following error monitoring and/or the Sd8 encoder monitoring.
The setpoint / quick stop ramps must be adjusted to the nErr monitoring in order to avoid incorrect error messages during operation.
