When to tune, When to tune 49 – MTS Series 793 User Manual
Page 49
When to Tune
MTS Series 793 Tuning and Calibration
Tuning Procedures
49
When to Tune
Tuning is needed whenever any of the following events occurs:
•
A gross change in the compliance or size of the test specimen. For example,
you were testing steel and change to rubber.
•
The servohydraulic configuration has changed. For example, a servovalve is
replaced or changed to a different capacity.
•
The system is sluggish (slow to react or not reaching the desired peaks).
However, this is not always a tuning problem; it could be insufficient
velocity capability such as a low-capacity servovalve.
•
If a control channel or sensor is recalibrated.
•
The system is unstable (indicated by a humming or screeching sound).
•
When you observe poorly controlled accuracy.
•
When you create a new control mode, or, if the sensor for a control mode is
changed.
•
The end levels or frequencies are significantly different from those observed
earlier in the test. For example, you notice that the specimen characteristics
change during the test (this could also mean the specimen is failing).
Checklist
Use this checklist when you tune a system. You need to determine the following:
•
What type of control mode do you wish to tune?
Read
“Tuning Characteristics of Control Modes”
•
What controls should you use?
Read
“How the Tuning Controls Work”
•
What kind of a tuning program should you use?
Read
•
Do you have a dummy specimen?
Read
•
Where do you connect the oscilloscope and what signal do you monitor?
Read
“Monitoring Waveforms While Tuning”
What to do before you
tune
The following are tasks that should be completed before you tune. It is not
necessary to perform every task each time you tune. The condition of your
system dictates which of the following tasks you must perform.