Page 78 ST 800 Series HART/DE Option User’s Manual Revision 5.0
Table 16 – Minimum PV Tracking
(Min PV Limit)
Lower Transducer Limit: PV(pressure)
specified lower operating limit in user-
selected units
for Stress
Condition
Actual limit value used in “Time Below
Limit” and “Time Since Last Event”.
Value is equal to “Min PV Limit” plus
10% of limits range for DP type
devices and zero for GP and AP type
For STD120 span is 0 to 400 inH
2
Range is 400 inH
2
O settable within
LTL = -800 inH
2
O to UTL = 800
inH
2
O limits.
“PV Lower Stress Limit” =
-800 inH
2
O + 160 inH
2
O = -640
GP Types
For STA140 allowable working
pressure is 0 to 500 psia.
Withstand Pressure from LTL = 0 to
UTL = 750 psia.
“PV Lower Stress Limit” = 0 psia.
None – calculation is automatic.
Minimum PV that the device has
experienced in user selected units.
None. Value initialized to Max PV Limit
value prior to leaving the factory.
Updates to current PV automatically
when powered at user site after one
Update after every 8 hours
Lower Stress
Limit
Accumulation of minutes that pressure
measured by the device has been
below the value of “PV Lower Stress
Backup once each 8 hour period
Last PV Down
Time that has passed since
the last time device’s PV
passed below the value of “PV
Lower Stress Limit” (in days,
None – initialized to zero prior to
leaving the factory.
Backup once each 8 hour period