Technical Specifications

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PST Configuration
Use this to configure PST, or partial stroke testing, operation.
Partial Stroke Test Settings
The configurable PST parameters are as follows (Figure 252):
Figure 252 PST Settings
 PST Travel - The allowed valve movement from full Open position in percentage of
travel. A typical value is 20%. Maximum allowed is 30%. The greater the travel range,
the more accurate the results from the PST test.
 Minimum Pressure – The allowed reduction in pressure in the actuator to achieve the
desired PST Travel. This value depends on the spring range and the valve/actuator
hysteresis. To set this value, first, run an Extended Actuator signature from the
Diagnostics screen. Then, locate on the Y-Axis of the signature, the X-Axis pressure
value for the desired Travel target. For example, if the PST Travel is 30%, what is the
pressure value to reach 70% travel. The Y-value selected must be on the upper curve
of the graph.