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5.1.3
Model 4234 Power Supply Unit – Fig. 5.5
Warning. Do NOT connect mains supply to the
power supply unit with the output terminals on open
circuit. This causes premature component failure.
Caution. Ensure that the power supply unit is
correct for the mains supply voltage available. A nominal
110V unit cannot be adapted for use with a nominal 240V
supply, or the other way around.
Remove the cover of the unit to gain access to the terminal
blocks inside.
Locate the terminal block (TB3) adjacent to the transformer T1.
To ensure the correct transformer tapping is used for the
incoming mains supply, adjust the brown wire, if necessary, to
the appropriately marked TB3 terminal to either 110 or 120V
(200, 220 or 240V, for alternative power supply unit).
Make electrical connections in accordance with the
information given in the wiring diagram Fig. 5.3 and Section
5.2.1.
The electrical connections are made at terminal blocks TB1
and TB2 through the appropriate cable gland, or any
replacement
gland
to
requirements. Secure the incoming cable by the cable clips
adjacent to the terminal blocks.
Fit the cover on completion of wiring up.
Spare fuse
FS1
Input
terminals
(TB1)
Cable clamp
Fig. 5.5 Location of Components Inside Case – Model 4234 Power Supply Unit
suit
intrinsically
safe
R103
Voltage selection
terminals (TB3)
5 ELECTRICAL INSTALLATION...
5.2 Intrinsically Safe Requirements
These requirements relate to the interconnecting wiring made
to and from Model 6548 000 Katharometer Analyzer Panel in
the hazardous area, and those for remote ancillary items
connected to the system.
5.2.1 Cable Requirements
The interconnecting cables between the various units of the
gas analysis system are subject to stringent limitations
because of the requirements of the intrinsic safety certification.
These are listed below and detailed in Fig. 5.4.
All cables entering the hazardous area must be kept separate
from cables in the safe area. Cables entering the hazardous
area must not be run with other cables, and terminations must
have an earthed screen to separate them from connections for
other circuits. The detailed requirements are as follows:
1) Connections between Model 6548 000 Katharometer
Analyzer Panel and Model 4234 Power Supply Unit.
All cables from the Katharometer in the hazardous area
must have an inductance/resistance ratio not exceeding
18µH/Ω, (for Group IIC gases). There is a further
requirement that the maximum resistance of this
interconnecting cable is limited to 2Ω. This may place a
limitation on the length of the total cable run.
wiring
C101 R101
D101
Cable clamp
D102 R104 RV101
C102
TR102
C103
Output
terminals
(TB2)
R102
TR101
Z101
D103
15
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