Electro-Pneumatic Positioner SP 520 Series
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Ver 1.20
16
SHIN HWA Eng.Co.,Ltd.
2-8 Principle of Operation
(1) LINEAR TYPE
When the input signal (4~20mA) is input, the input current is transmitted to the coil of the
Torque Motor (1) and magnetic force is generated in the core. Move to the left. As a result of
the action, the gap between the nozzle (17) and the spring support (5) is opened, and the
pressure in the nozzle pressure chamber (18) drops, resulting in a pressure difference with the
pressure chamber (19).
Accordingly, Spool (9) pushes Poppet A (12) to open port A, and the output of OUT1 raises the
diaphragm valve (3) valve to the top.
In accordance with this movement, the Feedback Lever (20) moves upward and transmits it to
the Output Shaft, and the port A closes and the output of out1 stops and the diaphragm valve (3)
is stopped until the pressure reaches the desired position by repeating the action.
Fig 2-5 : LINEAR TYPE operation principle
