Servomex DF-310E, Руководство оператора

Страница: 70 / 130

66 DF-310E User Interface
8.3.2 Sensor Polarization
After accessing the Sensor entry, the sensor power is toggled ON or OFF by pressing . The
sensor ON command applies a polarizing voltage to the sensor. See the section on ESC, page 67,
for additional information about leaving the menu after changing the Sensor setting.
The Analyzer has been programmed to protect the sensor from extended operation in an over-
range condition (> 30 minutes). If such a condition exists, the software will turn off the
polarizing voltage to the sensor. A message will be displayed indicating that the sensor has been
turned off, and an intermittent beep will occur as in Figure 35. The beep can be silenced and
message canceled by pressing ESC. When ESC is pressed a reverse video SENSOR OFF!
legend will overlay the oxygen display.
The user should investigate the reason for the excessively high O
2
level, remedy the situation,
and then restore power to the sensor via the Controls menu. The oxygen value is approximately
zero when the sensor is off. Also, the analog outputs will go to zero, so any low Oxygen alarms
set above zero will trigger on.
NOTE: The automatic sensor off function is disabled if the display is not in the main O2 readout
mode.
See the section on Remote Controls, page 47, for additional information on remote control of the
sensor polarization voltage.
Figure 35: Sensor Shut-off Warning
8.3.3 SensOFF Relay
When the sensor is manually turned off from the front panel, or automatically turned off because
the instrument has been over-range for more than 30 minutes, a relay may be assigned to signal
that the sensor is off. This feature is important when the Analyzer is used in an unattended area,
so that a remote operator can be notified that the instrument is no longer measuring oxygen. If
the instrument is not equipped with any relays this selection will show
NA . It is possible to
assign more than one alarm or status condition to any relay. Since the status condition of the
sensor, being switched off, signifies an “Analyzer Off-line” condition, it is important to make
sure that the relay assigned to SensOFF service is only assigned to alarm conditions signifying
similar levels of alert, such as a Low Flow Alarm.
Note: Alarm or Analyzer status conditions that signal an “Analyzer off-line” fault condition
(such as sensor off) can be assigned to a single relay contact used as a trouble indicator. If the
Analyzer signal is only monitored remotely, it is suggested to route the 4-20 mADC signal
through the “
Analyzer Trouble ” relay such that an alarm condition will cause the relay to break
the current loop. This method allows a computerized system to be configured to detect an
analyzer fault condition whenever the 4-20 mADC signal is below 4 mA.
                
               

                 
           
            