Seg SP760 Series, Instruction Manual

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Smart Positioner
SP760 Series
Ver 1.0 SHINHWA Eng.
- 12 -
is connected to lower cylinder(28) while upper cylinder is connected to exhaust pipe
raising piston rod(30) Lever(29) delivers a motion to output shaft (5) operating Pinion
(23) and Gear(24) and rotating potentiometer(22) from which the resistance is fed back
to control PCB(3). The feedback value is compared to the input value and calculated
accordingly; if any difference is found, a changed input current is delivered to coil (6)
of Torque motor(1) so to be properly located while repeating till it is balanced. On the
contrary, if input current is lower,Nozzle Flapper(9) block Nozzel (8) so that the pressure
in the nozzle pressure chamber(15) rises, spool (31) pushes poppet B (13) according to
the difference of pressure, opening port B while OUT 2 output is connected to upper
cylinder(27) and the lower cylinder(28) is connected to exhaust pipe, lowering piston rod
(30).Likewise, lever(29) delivers a motion to shaft(5),operating pinion(23) and gear(24),
rotating position transmitter (22) and finally delivering the resistance to control PCB(3).
1 Torque Moter 12 Poppet A 23 Pinion
2 Pilot Valve 13 Poppet B 24 Gear
3 Control PCB 14 Pressure Chamber 25 Limit S/W
4 Cylinder 15 Nozzle Pressure Chamber 26 Limit Cam
5 Output Shaft 16 Sheet Controller 27 Upper Cylinder
6 Coil 17 Diaphragm A 28 Lower Cylinder
7 Core 18 Diaphragm B 29 Feedback Lever
8 Nozzle 19 Diaphragm C 30 Piston Rod
9 Nozzle Flapper 20 Diaphragm D 31 Spool
10 Magnet 21 Pressure Regulator
11 Display 22 Potentiometer
Figure 2-3 Principle of operation