ABB 006539-960J, Руководство пользователя

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3
All the various system options comprise one or more of the
following units with the further option of fitting the display units
and power supply units in a cubicle.
Note . CO
2
is refered to throughout this manual as the
purge gas. However, other gases such as Argon or
Nitrogen may be used instead.
2.1 Model 6553 Display Unit
The 6553 Display Unit must be mounted in a
safe
area and is
suitable for panel mounting or installation into a control cubicle.
The 6553 Display Unit houses one or two 4689 (or CM30) digital
displays, each equipped with protected access for zero
adjustment, Model AK101 is equipped with a range selector
switch – see Fig. 2.1. Model AK104 is a single display for
Hydrogen purity and as such requires no range change selector
switch.
2.1.1 Range Display
A selector switch for each display provides independent
parameter selection as follows:
Position (1)
Percentage of Hydrogen in Air by volume
.
Displayed on the upper display.
This is the hydrogen purity measurement of the
coolant gas during normal operation of the
system. The display covers a range of 85 to 100%
or 80 to 100% hydrogen in air depending on the
range selected. An alarm output and a
retransmission signal (4 to 20mA) are provided.
Position (2)
Percentage of Hydrogen in Purge gas* by volume .
Displayed on the upper display.
This range is for use in hydrogen filling or purging
operation. Alarm output and a value
retransmission signal (4 to 20mA) are provided.
Position (3)
Percentage of Air in Purge gas* by volume
.
This range is for use in purge gas filling or purging
operations. Alarm output and a value
retransmission signal (4 to 20mA) are provided.
Each display defaults to NOT IN USE when not selected.
A further option of providing remote indication of range selector
switch may be available, depending on the number of alarms
specified.
The 4689 (or CM30) digital displays provide software specific to
the katharometer systems with relay action of the alarms fixed as
'fail safe'. All user-programmable data can be protected from
unauthorized alteration by a programmable 5-digit security
number.
The zero adjustments on the front panel enable remote zeroing
of the katharometers mounted in the
hazardous
area. The
adjustment access for a particular 4689 (or CM30) digital display
is adjacent to it at the same level
The 6553 Display Unit has a protective case that can be
removed for access to the interior without removing the whole
unit from the control panel.
The 6553 Display Unit also contains encapsulated zener diode
safety barrier devices to limit the electrical energy that can be
supplied from the instrument circuits into the
hazardous
area.
These devices are located below the 4689 (or CM30) digital
display(s), on a rail that
MUST
be earthed (grounded). A metal
screening arrangement segregates the connections made to
equipment in the
hazardous
area. The unit is protected on the
mains input side by two fuses, one for each circuit, accessible
from the front of the panel.
Fig. 2.1 Model 6553 Display/Control Units
2 DESCRIPTION
98.8
H2—CO2
U
II
N O
N SE
Hyd
rog
en
P
urity
& P
urg
e G
as
M
onito
r
Ran
ge
Range Selector
Switch
Digital
Displays
1
2
3
Zer
o
Zer
o
F1
AK101
U
II
N O
N SE
Hy
dro
gen
P
urity
M
onit
or
Digital
Display
Zer
o
F1
AK104
*Note . Purge gas options include:
CO
2
(Carbon dioxide)
N
2
(Nitrogen)
Ar (Argon)