6. Span and Zero Adjustment
①
Check the proper installation of the PPR positioner and the feedback shaft.
②
Check the proper position of a cam according to the actuator type (direct acting or reverse acting).
③
Connect all air connections.
④
Supply air and set the input signal to 3psi. Turn the zero adjusting screw clockwise or counter clockwise to set the zero
position.
⑤
Check the stroke of the control valve by setting the input signal to 15psi. If the stroke does not meet 100%, turn the span
adjusting screw clockwise or counter clockwise until 100% is reached.
⑥
Set the input signal back to 3psi and adjust the zero adjusting screw until the zero point is reached.
⑦
Repeat the process of
④
to
⑥
until the desired set points are reached.
⑧
If the strokes of the control valve perfectly meet 0% and 100%, each setting point of 6, 9, and 12psi is
automatically reached.
7. Wire Diagrams for Position Transmitter and Limit Switches
CAUTION: Always check that the electrical load is within the range stated on the nameplate.
Failure to remain within electrical ratings may result in damage to or premature
failure of the electrical switches, sensors or transmitter electronics.
8. Position Transmitter (4…20mA output signal)
A. Board View
B. Specifications
Power Supply Rating
5.5 ~ 30V DC loop-powered
Recommended Power Supply
24V DC
Output Signal
4~20mA
Operating Temperature
-20º to 70
℃
Load Impedance
0~600 ohms
Max. Output
30mA DC
Linearity
± 1.0 %
Hysteresis
1.0 % of full scale
Repeatability
± 0.5 % of full scale
Adjustment
Zero and Span in terminal box
C. With mA Loop calibrator D. With multimeter tester
E. Span and Zero Adjustment
①
Select RA or DA on a board in the terminal box. For reference, RA (reverse acting) is a standard factory setting.
②
Supply 4mA input signal and turn the zero adjusting screw on a board clockwise or counter clockwise until output signal
becomes 4mA.
③
Supply 20mA input signal and turn the span adjusting screw on a board clockwise or counter clockwise until output
signal becomes 20mA.
④
Repeat the process of
②
to
③
until output signal approaches input signal.
1. Be sure that Span and Zero of the EPR positioner should be exactly set before
setting Span and Zero of the position transmitter.
2. Be sure that 5.5 - 30V DC should be supplied in case of using the mA tester
(multimeter tester).
3. Check a loop power if the output power indicating lamp
⑥
is not on.
9. Limit Switches (open and close)
Contacts
SPDT Form C
AC Rating
16A 1/2HP 125/250VAC
DC Rating
0.6A 125VDC / 0.3A 250VDC
Adjustment
Cams with set screws (L-wrench included for setting)
10. Optional Restricted Pilot Valve Orifice
WARNING: Before removing the pilot valve, be sure to disconnect the positioner from the
signal and compressed air source
For improved control using smaller actuators, a restricted pilot valve orifice kit is
included with the positioner. To install, the pilot valve must be removed from the
positioner. Remove four screws holding the pilot valve to the positioner body. As
you remove the pilot valve, be sure to hold the compensation spring in place.
Flip the valve so the bottom faces you. Remove the o-rings from the
out 1
and
out 2
ports (as shown in the diagram at right). Place the orifice plates in their
place with new o-rings above them, and re-install the pilot valve, making sure
the compensation spring is back in place. The positioner is now set up for
smaller actuators.
11. Troubleshooting Tips
Troubles Solutions
There happens a hunting with a
small pneumatic actuator
The actuator is very small. Install two orifices at the bottom of the pilot
valve as instructed in 10. Optional Restricted Pilot Valve Orifice.
If the actuator is not small, check if a position shaft is inserted into the
output shaft of the actuator exactly. If there is a gap between these shafts,
make it tight.
The valve always opens
regardless of input signal.
The orifice of the Auto/Manual screw on the pilot valve is clogged.
Disconnect supply air and clean the orifice with a wire attached inside of
the EPR positioner cover as shown below.
Never move the seat adjuster. It was already set at the factory
precisely.
The valve always opens or
closes with input signal
The air connections are not made properly. Check again if the pneumatic
actuator type is RA (reverse acting) or DA (direct acting) and make the
proper air connections. See 7. Air Connections.
Linearity is very poor
Re-set Zero and Span.
Hysteresis is very poor
Tighten a mounting bracket.
12. Dimensions
Power-Genex Ltd.
44B9L, 434-9, Nonhyun-dong,
Namdong-gu, Incheon 405-848 Korea
Tel: +82-32-812-6644 Fax: +82-32-812-6645
www.powergenex.com [email protected]