Samson 3730-3 ESD - Page 11

The ramp time specifies the time required by
the valve to move through the travel range
100 to 0 % (falling) and 0 to 100 % (rising).
Note!
Times for the
Ramp time (falling/rising) are
determined during initialization of the
positioner. These times are not to be ex
-
ceeded when setting the parameters for the
partial stroke test with ramp function.
Cancellation conditions
To ensure that the running process is not dis
-
rupted and that the shut-off valve does not
slam shut unintentionally, it is advisable to
define conditions that cause the positioner to
cancel an active partial stroke test. The
positioner issues an alarm when a test has
been cancelled (see section 2.2).
Possible cancellation conditions are:
4
Max. test duration : The test is cancelled
when the maximum permissible test du-
ration (range: 30.0 to 3000.0 s) is ex-
ceeded.
4
x control value : The test is cancelled
when the value falls below the adjusted
valve position (range: –10 to 110 %).
The condition is only active when
Activa
-
tion x control
is set to “On“.
4
y control value : The test is cancelled
when the value falls below the adjusted
drive signal (range: 0 to 9999 1/s).
The condition is only active when
Activa
-
tion y control
is set to “On“.
Monitoring the drive signal y only makes
sense when the partial stroke test is per
-
formed as a ramp function because the
y cancellation condition is always met
with the step response function.
A suitable y control value can be deter
-
mined using the last performed partial
stroke test. After the test is completed, the
lowest drive signal value recorded by the
test is displayed under the Minimum
value y control (in TROVIS-VIEW 3 un-
der Display). This value should be used
as a reference value with a 15 % toler-
ance:
y control value
≈
0.85 x Minimum
value y control
.
4
ESD tolerance band : The test is cancelled
when the deviation of the valve position
(in relation to the step height) exceeds
the adjusted value (range: 0.1 to
100.0 %).
EB 8388-1 EN 11
ESD functions