8.3 Calibration of position transmitter
496-858 or 496-858/
The action sense of the valve (open or closed valve,
compared to the 4 - 20 mA of the loop signal),
determines the position of the connector 3 points
of the optoelectronic sensor on one of the two
connectors of electronic circuit A or B.
The operation rule is: for a clockwise rotation of
the pinion of the control shaft (view cover side),
the output current increases (4→20 mA) when the
connector of the optoelectronic sensor is connected
in A and decreases when connected in B.
• Linkage adjustment
When mounted on reciprocating valves, adjust the
turnbuckle to get the instrument lever perpendicular
to the plug stem at mid-travel.
• Position transmitter adjustment
– Position the connector 3 points on connector A
or B in function of the chosen action.
– Preset mid travel the zero adjustment (Z)
if necessary *.
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– Preset mid travel the span adjustment (S) if
– Configure the switch C (see annex II) on the
rotation angle of the control axle.
– Position the valve to the origin of travel that should
correspond to the minimum of the signal (4 mA).
– Install a milliamp meter in series in the loop and
power up the instrument.
– Rotate the primary pinion on the control axle to
get an output signal around 4 mA
– Fine tune-up of the 4 mA signal with the zero
– Full stroke the valve to the rated travel and
adjust the output signal to 20 mA with the span
– Check the zero and span calibration compared
to the valve stroke. Repeat the zero and span
calibration operations if necessary.
* In case of problem of Zero adjustment due to
the physical limits of the potentiometer, turn
of 5 turns in the reverse direction that desired
and turn the primary pinion to obtain an output
current nearest to 4 mA.
** In case of problem of span adjustment due to
the physical limits of the potentiometer, turn of
5 turns in the reverse direction that desired and
configure the switch C (see annex II) for a higher
or lower angle than that basis.
• Adjustment of micro-switch(es) or proximity
Refer to paragraph §8.1 or §8.2 to adjust micro-
switches or proximity switch(es).
• Strictly follow safety instructions under §7.4 before
putting into service.
496 Series Masoneilan Position Transmitter ATEX Instruction Manual | 19