MTS Series 793 - Manual (Page 59)

How to Set Servovalve Polarity
MTS Series 793 Tuning and Calibration Tuning Procedures 59
7. Interpret the actuator movement.
• If the actuator extends when a positive command is applied, the
servovalve polarity is correct.
• If the actuator retracts when a positive command is applied (and the
polarity setting is Normal), some electrical element that affects the
servovalve (such as conditioner polarity or cable orientation) has been
reversed and should be remedied.
• If the actuator begins in full retraction and applying a positive
command does not extend it, zero the command, remove hydraulic
pressure, and change the servovalve polarity. Then retry this test. If it
still does not move, return to Step 2 and increase the gain setting.
• If the actuator begins in full extension and applying a negative
command does not retract it, zero the command, remove hydraulic
pressure, and change the servovalve polarity. Then retry this test. If it
still does not move, return to Step 2 and increase the gain setting.
• If the actuator does not move at all, return to Step 2 and increase the
gain setting.
8. Set servovalve polarity to achieve desired actuator movement.