WIKA BWX - Manual (Page 3)

INSTRUCTION MANUAL
NI-222E
Rev. 1 12/02
Fig. 2 - Electrical connections and adjustment screws
One contact instruments Two contact instruments
Microswitch electrical circuit
State of the contacts at at-
mospheric pressure
1 - Microswitch set point calibration screws
3 - Terminal block
4 - Electrical connection identification plate 1 - Microswitch 2 set point calibration screws
2 - Microswitch 1 set point calibration screws
3 - Terminal block
4 - Electrical connection identification plate Designation of the contacts:
C - common
NA - Normally open
NC - Normally closed
5 - SET POINT CALIBRATION
In order to proceed with the calibration and the periodical
functional verification of the instrument a suitable cali-
bration circuit (fig. 5) and an adequate pressure source
is required.
5.1 PRELIMINARY OPERATIONS
Weatherproof pressure switches (BWX)
Remove the blocking device fixed to the side of the in-
strument case and the adjustment screw access plate
(Fig. 3). Remove the cover by rotating it in an anticlock-
wise direction.
Fig. 3 - Weatherproof pressure switch blocking device -
a - Plumbing wire
b - Plumbing
c - Blocking nut d - Blocking bracket
e - Adjustment screw access
plate
Explosionproof pressure switches (BAX) (Fig. 4)
CAUTION: do not open the cover of explosionproof
pressure switches (Series BAX) when energized, in
explosive atmospheres.
Loosen the locking headless screw situated on the
cover using a 1,5 hexagonal key then unscrew the cover.
Remove the internal blocking device inserted on the
closure plugs and slide out the plugs.
Fig. 4 - Explosionproof pressure switch blocking device
5.2 CALIBRATION CIRCUIT AND OPERATIONS
Prepare the control circuit as indicated in Fig.5.
The warning lamps should be connected to contact 1 or
2 in the NO or NC position according to the required
contact action.
Connection of C and NO terminals
• If the circuit is open at the working pressure, the
switch closes the circuit as the pressure increases
when the desired value is reached.
• If the circuit is closed at the working pressure, the
switch opens the circuit as the pressure decreases
when the desired value is reached.
Connection of C and NC terminals
• If the circuit is closed at the working pressure, the
switch opens the circuit as the pressure increases
when the desired value is reached.