Technical Specifications

ValVue Digital Communications Software Ver. 2.80

586

GE Oil & Gas

Auxiliary Signal Calibration Procedure

The Calibrate tab allows you to recalibrate the auxiliary signal sensor in the SVI. This sensor is

used as the process variable input when the SVI is used as a controller. The Reset to Factory

button returns the calibrations to those that were set before delivery of the SVI.

The currently measured value of the auxiliary input appears and can be compared to

reference signals to see if recalibration is necessary. Calibrating the auxiliary signal can be

done most easily with a variable current source.

The procedure for recalibration is:

Low Calibration

1. Click the Calib. 2nd Signal button. A dialog appears.

2. Enter 4 in the signal value field.

3. Set the current to 4.00 mA and click Set Low Signal.

High Calibration

1. Click the Calib. 2nd Signal button. A dialog appears.

2. Enter 20 in the signal value field.

3. Set the current to 20.00 mA and click Set High Signal.

Find

Stops

The Find Stop routine attempts to move the valve through out it’s full range to measure the

mechanical stroke of the valve. The calibration routine succeeds if the mechanical motion

measured by the travel sensor rotates more than the minimum required span and if the value

measured at both stops is within the limits of the travel sensor (18 deg. To 120 deg for

standard SVI or 9 to 60 degrees for short stroke version of SVI). A progress dialog appears

while the find stops process is running.

Correction can be made for nominal valve travel if it is less than full travel (see Open Stop

adjustment).

The following affects the Find Stop routine from succeeding:

 Insufficient or inadequate air supply to the positioner

 Improper adjustment of the reversing relay (if present)

 Steady state cannot be achieved at one or both mechanical stops

 External accessories (such as solenoids, trip valve, lock up valve, etc) restricting the flow

to the actuator

 Defective travel sensor

 Inadequate travel sensor rotation or rotation beyond the sensor’s limits.