Samson 373 Series Operating Instructions

80 EB 8389 EN
Tests
− The 'Ramp time (rising)' must be greater
than the corresponding value for 'Mini-
mum transit time close' (Code 41) deter-
mined during initialization.
− The 'Ramp time (falling)' must be greater
than the corresponding value for 'Mini-
mum transit time open' (Code 41) deter-
mined during initialization.
Users with expert knowledge of valve diag-
nostics can determine appropriate ramp
times by performing a full stroke test (see
section9.4).
− The 'Scan rate' must not be lower than
the indicated 'Min. recommended scan
rate'. The 'Min. recommended scan rate'
is calculated from the 'Duration of the
test'.
5.4.1 Start triggered by on/
off valve
3730-2 3730-3 3731-3 3730-4 3730-5 3731-5
• • • •
The partial stroke test of on/off valves is trig-
gered when the set point w moves away
from the operating point into the range be-
tween 25 and 50% of the travel range and
remains there for longer than six seconds
(see section4.1 and chart on page73).
'Step start' must be within the range of the
dened position ± 'Tolerance limit of step
response' for the partial stroke test to start.
The test and its cancellation are described in
section5.4, while the test assessment is de-
scribed in section5.4.3.
5.4.2 Start triggered by the
binary input
3730-2 3730-3 3731-3 3730-4 3730-5 3731-5
• • • •
If the positioner is tted with the optional bi-
nary input, the partial stroke test can be
started by the binary input when the condi-
tions to start the partial stroke test are met:
− A control valve is in the manual mode.
− An on/off valve is in the manual or auto-
matic mode. In automatic mode, the test
is only started when the 'Fail-safe refer-
ence value' is greater than the 'Limit fail-
safe position' (Code 49 - h2). In manual
mode, the test is only started when 'Tar-
get PST testing mode' = 'PST Man'.
The test and its cancellation are described in
section5.4, while the test assessment is de-
scribed in section5.4.3.
It is important to make sure that the diag-
nostic parameter 'Step start' of the partial
stroke test is within the range of the 'Fail-
safe reference value' ± 'Tolerance limit of
step response'.
Types3730-2/-3 and Type3731-3:
Settings > Positioner > Options
− Action at active binary input:
Start partial stroke test (PST)
Tip

Samson 373 Series Specifications

General

Brand	Samson
Model	373 Series
Category	Valve Positioners
Language	English