MTS Systems FlexTest SE Service Information

Model 493.02 Controller Service
About Tuning
Tuning
204
Delta P (∆P) Delta P is a differential pressure sensor that measures the difference in
pressure at each end of the actuator. It compensates for hydraulic
compliance (compressed hydraulic fluid acts like a spring). Delta P
improves displacement control of heavy mass loaded systems.
Delta P is typically used on systems with large hydraulic fluid flow
rates. This adjustment is usually needed when the natural frequency of
the actuator is less than the 90º phase lag frequency of the servovalve.
The servovalve 90º phase lag frequency can be found in the servovalve
product literature.
The natural frequency can be approximated with the following
formula:
• If the system response deteriorates when adding delta P, then
change the polarity of the signal. If changing polarity does not
improve system response, try adjusting the stabilization filter. See
“Stabilization Filter” on page 206
• Check all amplitudes for overshoot. Do not allow more than 10%
overshoot (preferably none) at any amplitude of a square wave
response.
• Delta P will not compensate for additional compliance from
swivels, linkages, test tables, and so forth. In this case, a mass
accelerometer signal from an accelerometer may be used in place
of a delta P signal for stabilization. See “Acceleration stabilization'
below.
Actuator Frequency
CA
WV
---------=
C = constant for English (2500) or metric units (1060)
A = actuator piston area expressed as in
2
(cm
2
)
W = any directly coupled mass including the actuator piston
mass expressed in lbs (kg)
V = hydraulic fluid volume contained inside the actuator and
manifold expressed as in
3
(cm
3
)
Where:

MTS Systems FlexTest SE Specifications

General

Brand	MTS Systems
Model	FlexTest SE
Category	Controller
Language	English