MTS Series 793 - Manual (Page 60)

MTS Series 793 Tuning and Calibration
How to Balance the Servovalve
Tuning Procedures 60
How to Balance the Servovalve
Balancing the servovalve involves a mechanical procedure performed on the
servovalve itself to achieve gross mechanical balance, and an electrical
adjustment performed with the controller’s Valve Balance control to fine-tune
the mechanical adjustment.
The mechanical procedure must be done before the electrical adjustment, and is
typically performed at system installation, when a new servovalve is installed in
an existing system, and when performance warrants it. The mechanical procedure
is detailed in the servovalve product manual (typically included in the system
documentation set).
The electrical adjustment is typically performed much more frequently than the
mechanical adjustment. 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 will be no (or minimal) hydraulic fluid flow when
the servovalve’s output signal is at null. The electrical valve balance procedure is
detailed in the following pages for both Standalone and automated Controllers.
If the servovalve cannot be balanced with the Valve Balance control, it may be
an indication of a major imbalance that requires a mechanical adjustment before
further electrical adjustments are made.
Valve clamping and
servovalve balance
Some systems use valve clamping as a means to control actuator behavior when
an interlock occurs. However, to clamp properly the servovalve must be balanced
before the interlock occurs.
Unexpected actuator movement is possible when the servovalve is
clamped.
Unexpected actuator movement can cause injury and equipment damage.
Your controller’s hardware interface file (.hwi) includes options to clamp the
servovalve when a hydraulic interlock occurs (these options cause the actuator to
stop, fully extend, or fully retract). However, if the servovalve is imbalanced, it may
move unexpectedly when clamped. Ensure the servovalve is balanced before
using your test system.
WARNING