TEMPERATURE CONTROLLER -5002U-P
REF NO: m55A/om/201
Issue NO: 03
Page
27
of
35
when the processing temperature comes to a balanced position near the setting value
and a constant temperature is maintained, the most suitable value is selected by
gradually narrowing the proportional band while observing the control results.
Manual Reset:
Virtually no process requires precisely 50% output on single output controls or 0%
output on two output controls. Because of this many older control designs
incorporated an adjustment called manual reset (also called offset on some controls).
This adjustment allows the user to redefine the output requirement at the set point. A
proportioning control without manual reset or Integral time (defined above) will settle
out somewhere within the proportioning band but likely not on the setpoint.
Some controls use manual reset (as a digital user programmable value), this allows
the user to preprogram the approximate output requirement at the setpoint to allow for
quicker settling atset point when Automatic reset (Integral time) set to zero. Range for
the manual reset is -50% to +50% of Proportional band.
Cycle Time:
The Cycle time for output is the time where the output is on for percentage of that time
and off for a percentage of that time, creating a portioning effect. The cycle time is
only used where PI, PD or PID control action is used. The shorter the cycle time, the
higher the proportionate resolution is, and better is the control.
For Relay output: Set to 10 to 30 seconds or more
Digital Filter (FLTR):-
In certain application the process value is too unstable to be read. To improve this, a
programmable low pass filter incorporated in the controller can be used. This is a first
order IIR filter with time constant specified by
FLTR
(FLTR)
parameter of
LEVEL-3
.
The input filter will reduce the oscillation or fluctuation of the process value. Excessive
filter can be dangerous, may produce an unstable process.
