Yokogawa YVP20S User Manual

Page 165

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17-4

<Toc> <Ind>

<17. FAILSAFE HANDLING>

IM 21B04C50-01E

To exit Failsafe for Case 1 and 3

Step 1

Restore the air supply or correct actuator problem.

Check that the pneumatics are working correctly.

Step2

Move the Failsafe dialog to one side of the screen to uncover the IVI display. (If
the PID dialog is open, close it.)

Step3

Record the Actual Position. (Shown as -39.92% in Figure 17.4) In this extreme
example, the valve calibration allows for large travel between closed stop and 0%
position.

Figure 17.4 Failsafe Steps 1 and 2.

Step4

This step requires privilege level 3, 4, 8 or 9.

Open the Operation State dialog, and select Manual, then click OK. In the
setpoint text box, enter the same value as the Actual Position, recorded in step 3.
Click OK. If the Failsafe dialog changes to Clear (Latched), then click the Clear
Latch button. When the dialog request a change to OOS, click Yes. If the Failsafe
dialog remains in Active (Latched) proceed to the next step.

Step5

This step requires privilege level 3, 4, 8 or 9

Open the Configuration dialog. Select the Position tab. Set the Tight Shutoff and
Position Low Limit parameters to -10 lower than the Actual Position recorded in
step 3. Set the Time 2 parameter to -1. See Figure 17.5. Click OK to accept the
changes, and then click Yes when a dialog warns of a change to OOS state. The
Failsafe dialog should change to Clear (Latched). Click the Clear Latch button.
When the dialog requests a change to OOS, click Yes.

Step6

This step requires privilege level 2, 3, 4, 8 or 9.

Open the Operation State dialog and select Manual, then click OK.

In the

setpoint text box, enter the same value as the Actual Position, recorded in step 3.
Click OK.

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