Series S Solid-State Staging Controller Instruction Manual
10
Series S Solid-State Staging Controller Instruction Manual
11
2.7 Span Adjustment – Left Side
This adjustment scales the input signal to the number
of output steps on. On standard units, it is factory
present to turn all heat stages ‘on’ with 20 mA input
and all heat stages ‘off’ with less than 4 mA. If signal
levels are low or if span is miscalibrated, with full
input signal applied, very slowly turn the adjustment
clockwise until all heat stages come on. Also, if it
is desired to limit the number of steps on, apply
full input signal to the controller and turn the span
adjustment counterclockwise to turn off steps.
2.8 System Adjustments
Dynamic stability of the whole system should be
optimized using the proportional band adjustment on
the controller that drives the staging controller.
A narrow proportional band will produce tight control
with minimal droop on load changes. If there are
multiple time lags between heater and sensor,
or it thermal coupling is loose, the system will
continuously overshoot and undershoot (oscillate).
A better sensor location or wider proportional band
setting should stabilize the process.
2.9 Fusing
The controller is supplied with 1A small glass fuses.
Littelfuse type 3AG or Bussman type AGC. These
fuses protect the triacs in the output boards from
shorts in the contactor or in the contactor wiring. for
slow acting or larger contactors, the fuses should
be replaced with littelfuse type 3AG ‘Slo-Blo’ or
Bussman type MDL (1A). Small contactors up to
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