Owner's manual

tina40e1-b (2011-04) 41
The gauges BCG450-SD and BCG450-SP have two independent, manually setta-
ble switching functions. Each switching function has a floating normally open relay
contact
1)
. 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 … 1000 mbar via potentiometers "SETPOINT A" and
"SETPOINT B".
U
Threshold
= 0.75 × (log p
Setpoint
– c) + 7.75
where constant c is pressure unit dependent (→ Appendix A).
Time t
M
e
a
s
u
r
e
d
v
a
l
u
e
Off
Off
On
Hysteresis
10% U
Threshold
Switching function
U
Threshold
Measuring signal
(Pressure p)
(Setpoint A, B)
The hysteresis of the switching functions is 10% of the threshold setting.
1)
Both setpoint relays (SP A/B, →  20) can be reprogrammed by the user to
work as atmosphere switching function relays (→  30 and  [1] or [2])
(SP A/B = default setting).
The threshold values of the two switching functions "SETPOINT A" and
"SETPOINT B" are set locally on the potentiometers of the gauge that are acces-
sible via the openings on one side of the gauge housing.
• Voltmeter
• Ohmmeter or continuity checker
• Screwdriver, max. ø2.5 mm
4.11 Switching Functions
(BCG450-SD, -SP)
4.11.1 Setting the Switching
Functions
Required tools