Rosemount Oxymitter 4000, Instruction Bulletin

Page: 59 / 127

IB-106-340
3-2
c. Verify Oxymitter 4000 Configuration.
Located on the microprocessor board, the top
board, are two switches that configure outputs for
the Oxymitter 4000 (Figure 3-2). SW1 deter-
mines if the 4-20 mA signal is internally or ex-
ternally powered. SW2 determines:
1. Oxymitter 4000 status, HART or LOCAL.
2. Oxygen range, 0 to 10% O
2
or 0 to 25% O
2
.
(0 to 40% O
2
is also configurable only
through HART/AMS.)
3. The 4-20 mA signal, at fault or power up,
4 mA or 20 mA.
Remove power from the Oxymitter 4000
before changing defaults. If defaults are
changed under power, damage to the
electronics package may occur.
d. SW1. The two settings are internally or
externally powering the 4-20 mA signal. The
factory setting is for the 4-20 mA signal to be
internally powered.
e. SW2. The factory sets this switch as follows:
1. Position 1 is HART/LOCAL. This switch
controls the configuration of the Oxymitter
4000. The defaults cannot be changed via
HART/AMS unless the switch is in the
HART position. Placing this switch in the
LOCAL position forces the O
2
range to the
setting of position 2. This switch must be
placed in the LOCAL position or changes in
position 2 will have no effect.
2. Position 2 determines the O
2
range. This can
be set to either 0 to 10% O
2
or 0 to 25% O
2
.
The factory setting is 0 to 10% O
2
.
Typically, the probe’s sensing cell, which
is in direct contact with the process gases,
is heated to approximately 1357°F
(736°C), and the external temperature of
the probe body may exceed 842°F
(450°C). If operating conditions also con-
tain high oxygen levels and combustible
gases, the Oxymitter 4000 may self-ignite.
If necessary, the O
2
range can be configured
from 0 to 40% O
2
. To select values within
this range, set position 1 of SW2 to HART
and then enter the range via HART/AMS.
Do not change position 1 of SW2 to LO-
CAL unless you want to operate in the range
specified by position 2 of SW2.
3. Position 3 determines the output at startup
or at an alarm. The settings are 4 mA or
20 mA. The factory setting is 4 mA. At
startup, the current at the analog output is
4 mA or 20 mA.
4. Position 4 is not used.
f. Once the cell is up to operating temperature, the
O
2
percentage can be read:
1. Access TP5 and TP6 next to the membrane
keypad. Attach a multimeter across TP5 and
TP6. The calibration and process gases can
now be monitored. Pressing the INC or DEC
once will cause the output to switch from the
process gas to the calibration gas. Pressing
INC or DEC a second time will increase or
decrease the calibration gas parameter. If the
keys have been inactive for one minute, the
output reverts to the process gas. When a
calibration has been initiated, the value at
TP5 and TP6 is the % O
2
seen by the cell.
Oxygen levels, as seen on the multimeter,
are:
8.0% O2 = 8.0 VDC
0.4% O2 = 0.4 VDC
2. HART/AMS.
3. Model 751. The loop-driven LCD display.