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Multi-Point Process Switch
EX-1711
Adjustment Procedure
The LED status indicators are used when adjusting the
individual set-points. When illuminated, they indicate
the set-point has been reached and corresponding relay
energized.
One method of adjusting set-points is to input a simulated
4-20 mA signal. By slowly varying the milliamp signal, the
precise value of the existing setting (including deadband)
can be determined prior to making any adjustments. This
procedure requires a very high
precision meter and milliamp source.
Generally, however, set-points are adjusted in-process.
Assuming the Process Switch is receiving the desired milliamp
(mAdc) input signal from the transmitter . . .
1. If the LED status indicator is not illuminated, turn the
Coarse
potentiometer clockwise (CW). As soon as the
LED is illuminated, slowly turn in the opposite direction
until it goes out. Very slowly turn potentiometer
clockwise but not so much as to trigger LED. (It may
be necessary to repeat this procedure to acheive the
“coarse” adjustment.)
If the LED status indicator is illuminated, turn the
Coarse
potentiometer counter-clockwise (CCW) until it goes
off. Very slowly turn potentiometer clockwise but not so
much as to trigger LED. (It may be necessary to repeat
this procedure to achieve the “coarse” adjustment.)
2. Turn FINE potentiometer clockwise (CW) very slowly
and stopping immediately as soon as LED is illuminated.
Warning!
If deadband is adjusted, all existing set-points will shift
accordingly. This will generally require re-adjustment of all
set-points. The deadband adjustment controls all set-points.
Deadband Adjustment
The MULTI-POINT Process Switch has been factory-adjusted
with a 1% FS deadband (0.16 mA). This represents the
range through which the input signal can be varied without
initiating a response at the output relays.
Deadband is adjustable up to 12.5% FS for applications
when greater tolerance of input fluctuation is required.
When deadband is adjusted, set-points will shift accordingly.
Note
—Deadband should be adjusted only by a skilled
technician. High-precision meters and signal generators
are required to accurately adjust the deadband setting.
Deadband Potentiometer
The adjustment pot for deadband settings is located inside
of the housing. See below.
Deadband
Potentiometer
