LEYBOLD IONIVAC Series - Switching Function Configuration

Operation
34
GA09420_002_C0 – (2016-10) –
 Leybold
4.8 Switching Functions (ITR 90 P)
The transmitter ITR 90 P has two independent, manually settable switching
functions. Each switching function has a floating normally open relay contact. The
relay contacts are accessible at the sensor cable connector (→  20).
The threshold values of switching functions A and B can be set within the pressure
range 1×10
-9
mbar … 100 mbar via potentiometers "SETPOINT A" and
"SETPOINT B".
Calculating the threshold voltage
U
Threshold
= 0.75 × (log p
Set
p
oint
– c) + 7.75
Constant c is pressure unit dependent (→ Appendix A).
The hysteresis of the switching functions is 10% of the threshold setting.
4.8.1 Setting the Switching Functions
The threshold values of the two switching functions "SETPOINT A" and
"SETPOINT B" are set locally on the potentiometers of the transmitter that are
accessible via the openings on one side of the transmitter housing.
Required tools
• Voltmeter
• Ohmmeter or continuity checker
• Screwdriver, max. ø2.5 mm
Procedure
The procedure for setting thresholds is identical for both switching functions.
 Put the transmitter into operation.
Time t
M
e
a
s
u
r
e
d
v
a
l
u
e
Off
Off
On
Hysteresis
10% U
Threshold
Switching function
Threshold
U
Measuring signal
(Pressure p)
(Setpoint A, B)