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SENSOR OPERATION AND INSTALLATION
1.0
Connect the gauge to the vacuum system, (can be connected in any position, but mounting with
the vacuum port facing down eliminates any chance of particles entering into the gauge).
2.0
Assure that there are no leaks.
3.0
Apply 24 DC volt power between pin #4 (+) and #2 (-). Monitor the signal output with a digital volt
meter between pin # 3 (+) and pin # 7. The display will show “OFF” and the signal output will be
between 10.5 volts and 14.5 volts.
4.0
The gauge is activated by grounding the wire from pin # 1 of the connector and may be operated
over any vacuum range, however, the following cautions.
4.1
Activate the gauge only at pressures below 10-2 Torr. Continuous operation above this
range will result in build up of contaminants inside the gauge and will produce errors in
reading. In addition, at even higher pressures the gauge may falsely indicate lower
pressures by having passed beyond the peak of its curve.
4.2
Initial activation of the gauge at pressures below 10-6 Torr may exhibit a delay in
providing an accurate reading of pressure until the electrical discharge within the tube
has established itself. This initial delay increases significantly at even lower pressures.
Once established the discharge within the tube is maintained over the entire range. A
very rough estimate of start time can be calculated as T, sec = 1/pressure in µTorr.
5.0
While the pressure is above the range of the gauge it will display “HI” and the signal output will be
just above the highest reading. If, on the other hand the pressure is below the lower gauge limit,
the display will display “LO” and the signal output will remain at its lowest value.
6.0
The trip pressure for the setpoint relay can be displayed by pressing the “Display Setpoint”
button. It can also be read as a voltage – anytime – on the wire pin # 9 of the connector. The
display will show the setpoint pressure as a blinking number (to distinguish it from a pressure
reading) until the button is again pressed or it times out automatically after 60 seconds. The
setpoint pressure can be changed only during the blinking display by means of the labeled
adjustment screw. The new value is retained in memory and the corresponding new voltage is
provided at the setpoint terminal on the connector and is scaled in the same way as the signal
output.
CHAPTER 4
TELEVAC
