MTS Series 793 Utility Software - Manual (Page 29)

If you manually added the hardware resources to the .hwi file, you must make sure that the address
setting in the .hwi file matches the physical address switch settings on the 493.40 I/O Carrier
board, 494.40 I/O Carrier Board, and the ADDA II board.
About Actuator Movement When the
Servovalve is Clamped
If an unbalanced servovalve (two-stage or three-stage) is clamped by Series 793 software, it may
act unpredictably. In addition, if a three-stage servovalve is clamped when its third stage is not
properly tuned, it may act unpredictably.
Servovalve balance
To balance a servovalve, you must first perform a mechanical adjustment on the servovalve to
achieve gross mechanical balance. You can then use the Series 793 software Valve Balance to
perform an electrical adjustment to fine-tune the mechanical adjustment.
Mechanical balance
The mechanical adjustment must be performed before the electrical adjustment, and is typically
performed at the following times:
• At system installation
• When a new servovalve is installed in an existing system
• If the servovalve cannot be electrically balanced
• At regular service intervals
Electrical balance
The electrical adjustment is performed with the Valve Balance control, which adjusts the electrical
input to the servovalve to compensate for minor mechanical imbalances. When the valve-balance
adjustment is complete, there should be no (or minimal) hydraulic fluid flow when the servovalve
output signal is at null.
Note:
The electrical adjustment is typically performed much more frequently than the mechanical
adjustment.
Inner-loop tuning
In addition to mechanical and electrical valve-balance adjustments, three-stage servovalves also
have inner-loop tuning controls that may affect clamping behavior. The inner loop is similar to a
displacement control mode for the outer-loop.
The inner control loop resides inside the test system’s primary, or outer control loop. So in addition
to the pilot spool, three-stage servovalves include a third stage (or main) spool, that is driven by
the pilot spool.
MTS Series 793 Utility Software 15
Create and Edit an HWI File