Samson 3760, Mounting And Operating Instructions

Page: 18 / 36

18
EB 8385 EN
Operation – Adjustment
Upper range value (travel)
e.g. 0.2 bar (4 mA)
5. After the starting point has been ad-
justed, set the input signal to 0.2 bar
(4 mA) at the remote adjuster (amme-
ter). The plug stem must stand still at an
upper range value of exactly 0.2 bar
(4 mA). It must have passed through
100 % travel (observe the travel indica-
tor on the valve!).
6. If the upper range value does not corre-
late, correct it using the SPAN adjust-
ment screw (8).
Turning the screw towards the fulcrum of
the lever increases the travel, whereas
turning it away reduces the travel.
NOTICE
If you change the span, the zero point must
be readjusted as well.
7. Check upper range value again. Read-
just both values until they are correct.
8. When you have completed the correc-
tion work, adjust input signal to 1 bar
(20 mA) again.
9. Turn ZERO adjustment screw (5) again
until the required signal pressure (sec-
tion 3.1.2 on page 13) is indicated on a
pressure gauge installed in the signal
pressure line.
If no pressure gauge is available, adjust
the starting point to 0.97 bar
(19.5 mA).
NOTICE
After adjusting the positioner, close the actu-
ator yoke with the cover plate.
Make sure that the vent plug in the cover
plate is directed downwards when the con-
trol valve is installed in the plant to prevent
condensed water from collecting in the
positioner.