Operation; Principle, Measuring Behavior - Oerlikon Leybold Vacuum PENNINGVAC PTR 90 Operating Manual

4

Operation

As soon as the required supply voltage is applied, the measuring signal is available
between pins 3 and 5. (→  26 for the relationship between the measuring signal
and the pressure).
Allow for a stabilizing time of approx. 10 min. Once the transmitter has been
switched on, permanently leave it on irrespective of the pressure.
4.1

Principle, Measuring Behavior

The transmitter consists of two separate measurement systems (Pirani and cold
cathode system) the signals of which are combined in such a way that one
measurement signal is output.
The optimum measuring configuration for the particular pressure range, in which
measurement is performed, is used:
10
Cald cathode
5×10 -9 mbar
•
The Pirani measuring circuit is always on.
•
The cold cathode measuring circuit is controlled by the Pirani circuit and is
activated only at pressures <1×10
The status output (pin 6) indicates the current status of the transmitter.
Pressure Green lamp on
the transmitter
-2
p >1×10 mbar
-2
p <1×10 mbar
-2
p <1×10 mbar
As long as the cold cathode measuring circuit has not ignited, the measuring value
of the Pirani is output as measuring signal (if p < 5×10
is displayed).
Gas type dependence
The measuring signal depends on the type of gas being measured. The curves are
accurate for N , O , dry air and CO. They can be mathematically converted for
2 2
other gases (→  28).
If you are using an Oerlikon Leybold Vacuum controller, you can enter a calibration
factor to correct the pressure reading (→
Ignition delay
When cold cathode measuring systems are activated, an ignition delay occurs. The
delay time increases at low pressures and is typically:
-5
10 mbar §1 second
-7
10 mbar §20 seconds
-9
5×10 mbar §2 minutes
-4 mbar
Pirani
10 -2 mbar
-2
mbar.
Operating mode
Pirani-only mode
Cold cathode not
ignited
Pirani-only mode
Cold cathode ignited
Combined Pirani / cold
cathode mode
-4
mbar, "Pirani underrange"
of that controller).
1000 mbar
Pin 6
Low = 0 V
Low = 0 V
High = 15 ... 30 VDC
GA09313_0202 – (2008-02) –
Operation
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Oerlikon Leybold Vacuum 13