D U N I W A Y S T O C K R O O M C O R P .
15 of 30
For the CVT, the next increment is 0.1 in the Least Significant Digit in the range 3.0 x 10
-3
torr
to 5.0 x 10
+2
torr.
When the
RAISE
or
LOWER
buttons are pressed, the display will change slowly at first. If you hold
the button down for a few seconds, the rate of change will increase to allow you to make large
changes more quickly.
SET
PT
1
HIGH
operates in conjunction with
SET
PT
1
LOW
. While the 960 is in this mode, the set
point may be assigned to either CCG or CVT/275 by pressing either
GAUGE
DISPLAY button.
E. Set Pt 1 Low Default Value: OFF
This sets the low limit of the set point. This is the pressure at which the set point relay will be
energized. Operation is similar to that of S
ET
P
T
1 H
IGH
above. The minimum value is
OFF
; this
shuts the set point off.
SET
PT
1
LOW
operates in conjunction with
SET
PT
1
HIGH
.
NOTE:
The High and Low set points allow the user to set the hysteresis of the set point
operation. As the system is pumped down, the set point relay will be energized (set point
turns on) as the pressure drops below
SET
PT
1
LOW
. The relay will remain energized until
the pressure rises above
SET
PT
1
HIGH
.
It is not possible to adjust the High set point to be lower than the Low set point. If you adjust the
High set point below the pressure previously selected for the Low set point, the 960 will automat-
ically reduce the value for the Low set point so that it is two increments lower than that of the
High set point.
F. Set Pt 2 High Default Value: OFF
This operates in the same manner as
SET
PT
1
HIGH
, described above.
G. Set Pt 2 Low Default Value: OFF
This operates in the same manner as
SET
PT
1
LOW
, described above.
Set Point Operation
When pressure values have been entered for a set point (1 or 2) and assigned to a gauge (CVT or
CCG), the set point relay operates as follows: As the pressure on the assigned gauge falls through
the chosen “Set Point N Low” pressure, the relay actuates, either opening (if the Normally Closed
pin has been used on the Auxiliary I/O connector) or closing (if the Normally Open pin has been
used on the Auxiliary I/O connector). Likewise, as the pressure on the assigned gauge rises
through the chosen “Set Point N High” pressure, the relay de-actuates, either closing (if the Nor-
mally Closed pin has been used on the Auxiliary I/O connector) or opening (if the Normally Open
pin has been used on the Auxiliary I/O connector).
NOTE:
See also Section VI - Application Note - Protective Circuits for Set Point Relays
NOTE:
See also Section IV-N - Set Point Activation/Deactivation Diagram
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