4 PRINCIPLE OF OPERATIONS
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4.3-4 ALARMS
Note
. The alarms cannot be set during a calibration sequence.
Waltron, L.L.C. has provided two hydrazine concentration alarm control relays,
each having one pair of changeover contacts rated at 2A, 250Vac (non-inductive).
Alarms 1 and 2 are designated as low and high alarms respectively. Display these
values by pressing the appropriate buttons on the front panel, and adjust by
pressing the “SET VALUE” buttons.
Terminal connections for alarms are shown in Section 2.4. The switches
“SW1.7”and “SW1.8” determine contacts that are closed in non-alarm conditions
- see Section 4.2.
Functions are as follows:
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In “NORMAL” the relays are de-energized; i.e. NC contacts are closed.
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In “FAIL-SAFE” the relays are energized, i.e. NO contacts are closed. If
the power source fails, both external alarms sound to indicate a
malfunction.
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Two other sets of relay contacts are provided: One set changes over during
a calibration sequence; and the other set changes over to indicate a failure
to calibrate.
4.4 ANALOG
OUTPUTS
Two identical isolated current outputs are available. You may set both outputs to
one of the three current ranges using switches “SW1.1” and “SW1.2”. In each
case, the upper current limit corresponds to the full-scale reading of the range
displayed on the front panel.
Note
. If “SW1.1” is set to “ON” and “SW1.2” is set to “OFF,” no valid output is
produced.
The two current outputs cover three decades of hydrazine concentration, divided
into two overlapping ranges.
The “RANGE SWITCH” on the front panel manually selects RANGES 1 (0 to
999ppb) or 2 (0 to 99.9ppb), but in “AUTO” mode, the monitor
switches automatically between these ranges as the hydrazine concentration
varies. Note the following points about ranges:
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