Siemens SINAMICS S120 System Manual page 244

Appendix
A.3 Hydraulic
Hysteresis, response sensitivity, range of inversion
These three terms define similar properties.
Hysteresis means the greatest difference in the input signal for identical output signals when
passing through a complete signal range.
For a servo solenoid valve, the hysteresis is caused by:
● mechanical friction,
● magnetic hysteresis of the electromagnetic signal transducer and
● the play between transmission elements.
The position control corrects the hysteresis.
The terms response sensitivity and range of inversion refer to the signal level required to set
a valve in motion again after it has stopped. The values of these characteristics correspond
to about half the hysteresis.
To overcome residual hysteresis or initial valve friction, a friction compensation function can
be activated in the HLA module.
Figure A-12
Filter mesh width
To maximize the service life of the control edges, thus ensuring the quality of zero overlap, a
certain degree of purity of the hydraulic fluid must be maintained.
The objective is to achieve pollution class 7...9 to NAS 1638. This can normally be achieved
with a pressure filter β10=75.
244
Hysteresis, response sensitivity and range of inversion of a servo solenoid valve
System Manual, 04/2015, 6SL3097-4BA00-0BP1
Hydraulic Drive