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TUNING THE OUTPUTS FOR HEATING CONTROL
TUNING THE OUTPUTS FOR HEATING CONTROL-cont. - TM-5-3895-374-24-2_467

TM-5-3895-374-24-2 M081 Asphalt Mixing Plant Manual
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TM 5-3895-374-24-2 955-257 5) The  PB  is  now  very  near  its  "CRITICAL"  setting.    Carefully  increase  or  decrease  the  PB  setting  until  cycles  or oscillations JUST appear in the temperature recording. If no oscillations occur in the process temperature even at the minimum PB setting of 1%, skip steps 6 thru 14 below and proceed to the Section: "TUNING PROCEDURE WHEN NO OSCILLATIONS ARE OBSERVED". 6) Read the steady-state deviation, or droop, between setpoint and actual temperature with the "CRITICAL" PB setting you have achieved.  (Because the temperature is cycling a bit, use the average temperature). 7) Measure the oscillation time, in minutes, between neighboring peaks or valleys. This is most easily accomplished with a chart recorder: but a measurement can be read at 1 minute intervals to obtain the timing. 8) Now, increase the PB setting until the temperature deviation, or droop, increases 65%. The desired final temperature deviation can be calculated by multiplying the initial temperature deviation achieved with the "CRITICAL" PB setting by 1.65 or by use of the convenient Nomogram I below.  Try several trial-and-error settings of the PB control until the desired final temperature deviation is achieved. NOMOGRAM I 9) You have now completed all the necessary measurements to obtain optimum performance from the controller.  Only two more adjustments are required; RATE and RESET. ECLIPSE INSTRUMENTATION DIVISION page 3-1100







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