MNA0010, Revision B October 2014
32
3.3
SET OR VIEW ALARMS
Alarms 1 & 2 are indicated by a red
LED plus dry relay contacts. The
alarms will be indicated when the
oxygen concentration has violated
the threshold criteria of the
respective alarm setpoint. The
Alarm status will be cleared when
the alarm condition has ceased.
The alarm relay conditions will be “frozen” when entering the calibration or set alarm modes.
The alarms will be re-enabled two minutes (factory default) after no buttons have been pushed.
Ascending or Descending Trip?
Alarms may
be configured with ascending or descending
trip. An ascending trip means the alarm will
activate due to an increase in oxygen
concentration above the setpoint
programmed into the Model 7100.
Descending trip will cause an alarm to
activate due to a decrease in oxygen
concentration below the setpoint
programmed into the Model 7100. The
oxygen concentration setpoints are
programmed as described below.
Fail Safe or Non-Fail Safe?
Optional Relay
Alarms may be configured as fail safe or
non-fail safe. This choice is provided to
those customers who may prefer an alarm
configured in a particular manner for safety
reasons. Many companies prefer alarm
relay actions to default to alarm condition
when power to the instrument is lost. That
is, the relay contacts are the same as for
alarm condition as for a lost power condition.
This is “Fail Safe”.
In fail safe configuration, the alarm relay
coils are de-energized in alarm mode and
energized in normal operating (non-alarm)
state.
In contrast, an alarm configured as Non-Fail
Safe operates such that the relay coils must
be energized to activate an alarm condition.
When power is lost to the instrument, the
relay contacts default to their normal non-
alarm state.
In non-fail safe configuration, the alarm relay
coils are energized in alarm mode and de-
energized in normal operating (non-alarm)
state.
What is the factory setting?
Alarm Relays 1
& 2 are factory set to non-fail safe and to
Ascending trip. These settings may be
changed in the field by accessing the main
circuit board jumper configurations. If
specified at the time of the order, Neutronics
will configure the alarm relays to the
customer specification. Refer to the
certificate of analysis that accompanies
every shipment and to the appendix of this
manual.
MODE
RUN
FAULT
ALM 1
ALM 2
9.9
T
RACE
O
XYGEN
MODEL 7100 O
2
Analyzer
Mini-Zirconia
Sensor
NTRON