WIKA DA10 - Manual (Page 5)

INSTRUCTION MANUAL
NI-209E
Rev. 4 12/02
6.3 ELECTRICAL CONNECTIONS
It is recommended to carry out the electrical
connections according to the applicable standards. In
case of explosionproof instruments (Series DA) see also
the Standard EN-60079-14. If the electrical connection
is carried out in a protected tube, it shall be made so
that condensate is prevented from entering instrument
enclosure.
The arrangement shown in figure 7 and 8 is therefore
recommended.
CAUTION: fittings used for the electrical connection of
the pressure switch Series DA (explosionproof) shall be
certified to Standards EN 50014 and 50018, and shall
guarantee instrument degree of protection (IP65).
Check that there is no power in the lines. Remove the
cover and carry out the cabling and connections to the
terminal block (see Fig. 2). Flexible cables with a
maximum section of 1.2 mm
2 (16AWG) are
recommended using pre-insulated fork thimbles. Do not
touch the adjustment screws and do not bend the
elastic microswitch supports in order to prevent the
instrument calibration being altered. Ensure that no
deposits or wire ends remain inside the case.
As soon as connection steps are completed, mount the
cover on and make sure it is tight and blocked See Fig.
3 and 4.
6.4 SPECIAL NOTE FOR INSTALLATION OF
CATEGORY 1/2 G PRESSURE SWITCHES
Explosionproof pressure switches (Series DA) can be
installed on processes requiring apparatus of group II
category 1 in an ambient requiring apparatus of group II
category 2 (see Fig. 6).
Fig. 6 - Installation of Group II Cat. 1 / 2 G instruments
7. INSTRUMENT PLUMBING
Weatherproof pressure switches (Series DW)
The plumbing, aimed as a guarantee against possible
tampering of the calibration and electrical connections,
can be carried out using a flexible steel wire (a) inserted
into the holes in the locking nut (c) and the bracket (d)
provided for this purpose (see Fig. 3).
Explosionproof pressure switches (Series DA)
Plumbing is not necessary as the cover is blocked with a
headless screw, the closure plugs of the adjustment
screw access holes are blocked by means of the
internal blocking device and the instrument does not
have to be opened when installed (see Fig. 4).
8. PUTTING INTO OPERATION
As the signal transmitted by the instrument is used in a
complex system, it is necessary that the means of
putting it into operation are established by personnel in
charge of the plant
.
The instrument comes into operation as soon as the root
valves are opened and then, afterwards, the service
valve attached to the instrument + inlet pipe is opened,
the by-pass valve closed and the service valve attached
to the instrument - inlet pipe is opened. Any possible
drainage of the connection tubing can be carried out by
opening the drains positioned on the instrument.
In case of explosionproof instruments (Series DA), initial
inspections are to be carried out according to customer
procedures and at least in accordance with Standard
EN-60079-17.
NOTE: if the instrument is used for level control in
tanks under pressure and is installed according to the
diagram in Fig. 10 proceed as follows:
Close the root valves V1 and V2 open the valves V3 V4
V5 (the service and by-pass valves). Fill with the
process fluid, from plug SB positioned on the seal pot B,
bleeding air from the plug S positioned on the seal pot
near the V2 valve. Then close S and top up the liquid in
B. Remove air from the breather plug S+ and S-
positioned on the instrument, topping up the liquid in B.
Close the plug SB and the by-pass valve V5 and open
the root valves V1 and V2. The instrument is ready for
use.
9. FUNCTIONAL VERIFICATION
This will be carried out according to the Client’s control
procedures. Series DW instruments can be verified on
the plant if installed as illustrated in Fig. 7 or 8.
The instruments Series DA may be checked on site only
if apparatus suitable for explosive atmospheres are
used and provided that the electric line is not
energized.
If this is not the case it is necessary to stop operation,
dismount by means of the three piece joints and carry
out the verification in a test room.
CAUTION: do not open the cover of explosionproof
pressure switches (Series DA) when energized, in
explosive atmospheres.
Verification consists in checking the calibration value
and possibly regulating the adjustment screw (see
par.5).
In case of explosionproof instruments (Series DA),
inspections of the electrical installation are to be carried
out also according to customer procedures and at least
in accordance with Standard EN-60079-17.