
Electro-Pneumatic Positioners YT-1000L Series
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TROUBLESHOOTING
▶ Positioner does not respond to the input signal.
(1) Check supply pressure level. The lever must be at least 1.4 kgf/cm2. For
spring-return type of actuator, the supply pressure level has to be larger than the
spring's specification.
(2) Check if input signal is properly supplied to the positioner. The signal should be
4~20mA DC.
(3) Check if zero point or span point is properly set.
(4) Check if the positioner's nozzle has been blocked. Also, check if the pressure is
supplied to the positioner and the pressure is being exhausted through the nozzle.
If the nozzle has been block by any substances, please send the product for
repair.
(5) Check if feedback lever has been installed properly.
▶ The pressure of OUT1 reaches exhausting pressure level and does not come back
down.
(1) Check A/M Switch. If the switch has been damaged, replace the switch or pilot
relay valve.
(2) Check for a gap or damages between the nozzle and the flapper. If damaged,
please send the product to YTC for repair.
▶ The pressure is exhausted only by A/M Switch.
(1) Check if the positioner's nozzle has been blocked. Also, check if the pressure is
supplied to the positioner and the pressure is being exhausted through the nozzle.
If the nozzle has been blocked by any substances, please send the product to
YTC for repair.
▶ Hunting occurs.
(1) Check if safety spring has been displaced. (Next to Pilot relay valve)
(2) Check if the size of actuator is too small. If so, insert an orifice in order to
reduce the pressure flow rate.
(3) Check if there is any friction between the valve and the actuator. If so, increase
actuator's size or reduce the friction level.
▶ Actuator only operates by On/Off.
(1) Check actuator and positioner's acting type. Air pressure exhausts from
YT-1000L's OUT1 port as input signal level increases. Therefore, it is standard to
connect to OUT1 port when single actuator is used. Make sure the span
adjustment is properly set according to the valve system.
▶ Linearity is too low.
(1) Check if positioner is properly positioned. Especially check if the feedback lever is
parallel to the ground at 50% point.
(2) Check if zero and span point have been properly adjusted. If either one of values
is being adjusted, another one must be re-adjusted as well.
(3) Check if supply air pressure level is stable from the regulator. If the level is