Samson 3760 Service manual

Mounting and
Operating Instructions
EB 8385 EN
Edition July 2012
Pneumatic Positioner
Electropneumatic Positioner
Type 3760
Type 3760 Positioner

Contents
1 Design and principle of operation. . . . . . . . . . . . . . . . . . . . 6
2 Attachment to actuators . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1 Adjusting the operating direction . . . . . . . . . . . . . . . . . . . . 8
2.2 Installing the clamp . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3 Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1 Pneumatic connections . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1.1 Signal pressure indication . . . . . . . . . . . . . . . . . . . . . . . 13
3.1.2 Supply pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1.3 Degree of protection IP 65 . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 Electrical connections . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.1 Switching amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4 Operation – Setting . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1 Starting point and reference variable . . . . . . . . . . . . . . . . . . 15
4.2 Adjustment for "Actuator stem extends". . . . . . . . . . . . . . . . . 16
4.3 Adjustment for "Actuator stem retracts". . . . . . . . . . . . . . . . . 17
5 Adjusting the limit switch . . . . . . . . . . . . . . . . . . . . . . . 18
5.1 Retrofitting a limit switch . . . . . . . . . . . . . . . . . . . . . . . . 18
6 Converting the positioner . . . . . . . . . . . . . . . . . . . . . . . 20
6.1 Conversion from pneumatic p/p to electropneumatic i/p . . . . . . . . 20
6.2 Conversion from electropneumatic i/p to pneumatic p/p . . . . . . . . 21
7 Dimensions in mm. . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2EB 8385 EN
Contents

EB 8385 EN 3
Safety instructions
4The positioner is to be mounted, started up or operated only by trained and
experienced personnel familiar with the product.
According to these Mounting and Operating Instructions, trained personnel re-
fers to individuals who are able to judge the work they are assigned to and
recognize possible dangers due to their specialized training, their knowledge
and experience as well as their knowledge of the applicable standards.
4Explosion-protected versions of this positioner may only be operated by per-
sonnel who have undergone special training or instructions or who are autho-
rized to work on explosion-protected devices in hazardous areas.
4Any hazards that could be caused by the process medium, the operating pres-
sure, the signal pressure or by moving parts of the control valve are to be pre-
vented by means of the appropriate measures. If inadmissible motions or for-
ces are produced in the actuator as a result of the supply pressure, the supply
pressure must be restricted by means of a suitable supply pressure reducing
station.
4Proper shipping and appropriate storage are assumed.
4Note: The device with a CE marking fulfils the requirements of the Directives
94/9/EC (ATEX) and 89/336/EEC (EMC). The declaration of conformity is
available on request.

4EB 8385 EN
Versions
Positioner Type 3760- XXXXXX
Explosion protection Without
II 2G Ex ia IIC T6 acc. to ATEX
CSA/FM
II 3G Ex nA II T6 acc. to ATEX
0
1
3
8
Additional equipment Without
Inductive proximity switches
0
1
Pneumatic connections G 18
18NPT
1
2
Electrical connections Without
M20 x 1.5 blue
M20 x 1.5 black
Connector DIN 43650
0
1
2
3
Reference variable 0.2 to 1 bar/3 to 15 psi
4 to 20 mA with i/p module 6109
0 to 20 mA with i/p module 6112
1 to 5 mA with i/p module 6112
0
1
2
2
0
1
2
3

EB 8385 EN 5
Technical data
Travel range 0 to 5 mm · 0 to 7.7 mm · 0 to 15 mm
(see page 11 for range spring table)
Reference variable pneumatic 0.2 to 1.0 bar (3 to 15 psi)
electric 4 to 20 mA (also 0 to 20 mA with 6112 i/p module) · 1 to 5 mA
Split-range operation
0 to 50 % or
50 to 100 %
with 7.5 and 15 mm travel
Internal resistance at 20 °C
4 to 20 mA: 200 Wfor safe areas · 250 Wfor hazardous areas
0 to 20 mA: 200 W
1 to 5 mA: 850 W
Supply air 1.4 to 6 bar (20 to 90 psi)
Signal pressure 0 to 6 bar (0 to 90 psi)
Characteristic Linear, deviation from terminal-based conformity £1.5 %
Direction of action Reversible
Hysteresis £0.5 %
Sensitivity £0.1 %
Steady-state air consumption £100 ln/h at 0.6 bar signal pressure and supply pressure up to 6 bar
Air output capacity At Dp 1.4 bar: 1600 ln/h · At Dp 6 bar: 5000 ln/h
Transit times with Type 3277 Actuator
(15 mm travel, 0.2 to 1 bar signal
pressure)
120 cm²: £2 s · 240 cm²: £6 s · 350 cm²: £8 s
Permissible ambient temperature
–20 to +70 °C
Down to –30 °C with metal cable gland
Down to –40 °C with metal cable gland and Type 6112 i/p Converter
Limits in test certificates additionally apply for explosion-protected devices.
–40 to +70 °C for Type 3760-00x000 Pneumatic Positioner without inducti-
ve limit switch
Influence
Temperature: zero point: £0.03 %/°C · Span: £0.03 %/°C
Vibrations: between 5 and 120 Hz as well as 2 g £0.5 %
Supply air: £0.6 %/1 bar
Electromagnetic compatibility Requirements specified in EN 61000-6-2, EN 61000-6-3 and EN 61326-1
fulfilled
Variable position when turned 180° < 3.5 %
Degree of protection IP 54 (IP 65 with filter check valve, refer to accessories)
Weight Approx. 0.6 kg
Materials Housing: polyamide · External parts: stainless steel
Additional electrical equipment
Inductive limit switch Type SJ2-SN
Control circuit Values corresponding to downstream switching amplifier
Hysteresis at rated travel £1 %

1 Design and principle of
operation
The pneumatic or electropneumatic
positioner ensures a preselected assignment
of the valve stem position (controlled vari-
able x) to the control signal (reference vari-
able w).
The input signal received from a control unit
is compared to the travel of the control
valve, and a corresponding pneumatic sig-
nal pressure (output variable) is produced.
The positioner mainly consists of a pneu-
matic unit including a clamp (10), range
spring (7), diaphragm lever (4) and a
booster (12) with a double plug (13).
The electropneumatic positioner is addition-
ally equipped with an electropneumatic con-
verter (2).
The positioner is designed for direct attach-
ment to SAMSON Type 3277 Actuators.
The control signal from the control unit, pro-
vided it is a pneumatic signal, is applied di-
rectly to the measuring diaphragm (3) as
pressure signal pe. Whereas a DC current
input signal in the range of 4 to 20 mA, for
example, is directly passed on to the
electropneumatic converter (i/p converter),
where it is converted into a proportional
pressure signal pe.
The pressure signal peproduces a force on
the measuring diaphragm (3), which is bal-
anced by the force of the range spring (7).
The deflection of the diaphragm (3) causes
the diaphragm lever (4) to move. The double
plug (13) in the booster (12) follows this mo-
tion, producing a signal pressure pst.
The operating direction of the signal pres-
sure, either increasing >> or <> decreasing
when the input signal increases, depends on
the position of the booster which can be ro-
tated by 180°.
A change in either the input signal or the
valve position causes a pressure change in
the booster. The output pressure pst of the
booster moves the plug stem to a position
corresponding with the given control signal
(reference variable).
The adjustment screws for ZERO (5) and
SPAN (8) are used to adjust the lower and
upper range value of the input signal.
The range spring (7) must be chosen to
match both the rated valve travel and the
nominal span of the reference variable.
6EB 8385 EN
Design and principle of operation

EB 8385 EN 7
Design and principle of operation
Fig. 1 · Functional diagram
1
Supply
2i
14
14
13 12 11 10 9 8
3
pe
pe
pst
pst
4567
Span
Booster
direction of action >>
Booster
direction of action <>
Travel
Zero
1 Pressure regulator
2 i/p converter
3 Measuring spring
4 Diaphragm lever
5 Adjustment screw for
zero
6 Lever
7 Range spring
8 Adjustment screw for
span
9 Clamping screw
10 Clamp
11 Rotary axis
12 Booster
13 Double plug
14 Screw

2 Attachment to actuators
The positioner is attached directly to the ac-
tuator yoke using the two screws inside the
housing. The rubber profile serves as a seal
between positioner housing and yoke.
The following accessories are required to
mount the positioner: clamp, cover plate and
a plug with seal.
The required mounting kit is listed in the ta-
ble on page 12.
For attachment to 120 cm² actuators
(Fig. 3), remove the filter installed in the side
signal pressure connection. The connection
(output 36) must be sealed by a plug with
seal (see accessories).
The signal pressure is routed over the signal
pressure hole at the back of the housing di-
rectly through the yoke into the associated
diaphragm chamber.
When attaching the positioner to the yoke,
make sure that the seal containing a filter is
installed in the side hole of the yoke.
How the signal pressure is supplied to the
actuator depends on whether the positioner
is attached on the left or right side of the
yoke. For this purpose, the corresponding
symbol on the switchover plate must be
aligned with the mark (point) on the yoke.
If, in addition to the positioner, a solenoid
valve or a similar device is to be attached to
the actuator, the signal pressure hole at the
back of the positioner housing must be
sealed. To do so, remove the screw installed
(parking position) in the hole below the sig-
nal pressure hole and screw it into the signal
pressure hole.
In this case, the signal pressure must be
routed from the signal pressure connection
(output) to the actuator using a connecting
plate. The switchover plate is no longer
used.
Note: Switchover and connecting plates are
accessories for the 120 cm² actuator. For
details, see table on page 12.
For attachment to 240 and 350 cm² actua-
tors (Fig. 2), the signal pressure must be
supplied to the signal pressure connection of
the actuator using the appropriate hook-up.
The required hook-up kit is listed in the table
on page 12.
Furthermore, the signal pressure hole on the
back of the positioner housing has to be
sealed. To do so, remove the screw installed
in the hole below the signal pressure hole
(parking position) and screw it into the sig-
nal pressure hole (see Fig. 3).
2.1 Determinng the direction of
action
The positioner's direction of action also de-
termines its attachment position on the actu-
ator, either on the left or right side of the
yoke as illustrated in Figs. 3 and 2. The po-
sition of the booster (12) must be arranged
accordingly on the positioner.
When the input signal (reference variable)
increases, the signal pressure pst may either
increase (direct action >>) or decrease (re-
verse action <>). The same applies when the
input signal decreases. For direct action >>,
the signal pressure decreases, whereas it in-
creases for reverse action <>.
8EB 8385 EN
Attachment to actuators

EB 8385 EN 9
Attachment to actuators
output 36
pst
Fig. 2 · Mounting position of positioner with 240 and 350 cm² actuators
Signal pressure connection with hook-up for
240 and 350 cm²
Actuator stem extends
Direction of action >>
Left attachment
Direction of action <>
Right attachment
Actuator stem retracts
Direction of action <>
Left attachment
Direction of action >>
Right attachment
Vent plug
with filter check valve for IP 65
Fig. 3 · Signal pressure connection using a switchover plate for 120 cm²
Hole for signal
pressure
Screw
(parking position)
Seal with
filter
Marking
Symbol
Actuator stem extends Actuator stem retracts
Attachment: Left Right Left Right
Direction of action: >> <> <> >>
Switchover plate

The symbols indicating the direction of
action are marked on the booster. The de-
sired symbol must be aligned with the arrow
stamped on the positioner housing.
If the indicated symbol does not correspond
with the required direction of action, pro-
ceed as follows: remove the mounting screw
and booster. Rotate booster by 180°, rein-
stall it and fasten it with the screw.
Note: If the adjusted direction of action of
an attached positioner must be changed at a
later stage, the mounting positions of the
booster and positioner on the valve must be
changed as well.
Attachment on the left or right side specifies
that, when looking onto the switchover plate
or the signal pressure connection, the
positioner must be secured on either the
right or left side of the actuator yoke. The
signal pressure output (output 36) of the
positioner must point to the front towards the
connections (Fig. 2).
2.2 Mounting the clamp
After attaching the positioner to the yoke,
the clamp must be secured to the actuator
stem on the opposite side (Fig. 4).
1. Insert the clamp in the yoke next to the
actuator stem (for 120 cm² actuators, tilt
by 90° prior to inserting it).
2. Plug the clamp onto the actuator stem
and secure it with the clamping screw.
Make sure that the clamping screw rests
in the groove of the actuator stem and
that the clamp is aligned at an exact
right angle.
3. Hook up the range spring between the
lever of the clamp and the SPAN adjust-
ment screw, placing it in the outer
groove with 5 and 6 mm travel and in
the inner groove with 10.5 and 12 mm
travel. Turn ZERO adjustment screw to
slightly tension the spring.
The range spring of the positioner is as-
signed to different travels and input ranges
which must be selected according to the ta-
ble on page 11. The range springs are
color-coded.
Adjust the positioner before closing the actu-
ator yoke with the cover plate (see
section 4).
When making adjustments during op-
eration, the actuator is under pres-
sure. The moving actuator stem can
cause severe injuries to hands and
fingers.
Always use tools when working on
the clamp and range spring!
10 EB 8385 EN
Attachment to actuators