Electro-Pneumatic Positioner SP 520 Series
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Ver 1.20
17
SHIN HWA Eng.Co.,Ltd.
(2) ROTARY 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. With this magnetic force, the
flapper (4) receives the force to the right and the spring support (5) is Move to the left. As a
result of the action, the gap between the nozzle (17) and the spring support (5) is widened 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 pushes
Actuator(3) to the right, rotates actuator stem(21), and is transferred to Cam(20).
According to this movement, the Span Lever(6) is moved and the spring support(5) is pulled
through the Span lever spring(14), and the gap between the nozzle(17) and the spring
support(5) becomes narrow again, and port A is closed and the output of out1 This stopping
and stopping the actuator (3) is repeated until the pressure is equalized to reach the desired
position.
Conversely, if the input current is small, the nozzle flapper (9) blocks the nozzle (8) and the
pressure in the nozzle pressure chamber (18) increases, and the spool (9) becomes Poppet B
(8) according to the pressure difference with the pressure chamber (19). Push to open port B
and the output of OUT2 is connected to the actuator (3), and the actuator stem (21) rotates.
Fig 2-6 : Rotary TYPE operation principle
