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Masoneilan 7700E UA TR Instructions Manual | 5
1. Instrument Operation
The Model 7700E electro-pneumatic positioner operation principle is a force-balance mechanism:
•
An entry force exerted by the double diaphragm under the effect of a pneumatic signal pressure.
•
An opposite force developed by a feedback spring. The tension of this spring varies with the
displacement of the actuator lever to which it is connected.
•
The pneumatic signal pressure on the double diaphragm is generated by an I/P 4000 converted
plugged on the positioner manifold block. This one converter a 4-20mA current signal to a
normalized 3-15PSI pneumatic signal.
•
Model 7700E electro-pneumatic positioner can be used only on Varipak valve 28000.
2. Numbering System
Unique positioner: 7700 E (with I/P 4000 module).
Different versions:
•
Housing material:
o
Aluminum
o
Stainless steel
•
Actuator mounting on Varipak valve model 28000:
o
Single lever: 28001
o
Adjustable C
v
: 28002
3. Technical Data
3.1.
Performances
Performances
(% of the signal range)
Started point (closed valve)
2,0 %
Hysteresis (mid-stroke)
0,9 %
•
Maximum service temperature range: -40°C to +85°C
•
Storage temperature: -55°C to +90°C
•
Housing protection: IP66 (I/P converter Module)
•
Input signal: 4-20 mA,
•
Input impedance: 170 ohms.
•
Cable entry on the I/P 4000:
o
½”NPT
o
M20 (with an adaptor
½”NPT/M20)
3.2.
Schematic
REP.
Designation
REP.
Designation
REP.
Designation
K115
Spring clamp
C
Cover
S
Supply
K116
Take up screw
J
O ring
V
Safety screw
K117
Locknut
O
Output
K116
K117
K115
