Jamesway Sentry Manual page 111

8.2 Alarm Description
This section describes how the alarming system operates on the sentry system, and explains what the
various alarms indicate.
Alarm operation of a machine controller depends on how the alarms are programmed to operate, which is
done through the 'Alarm Setup' function of Section 4.5 on Page 19. If an alarm is disabled, the alarm
condition will not be shown on the display panel, even though internally the machine still knows about
the alarm condition and takes corrective action. For example if the 'Damper Sensor' alarm is disabled, the
machine will still disable damper movement. The 'Delay Before Alarming' setting determines how long an
alarm has to be active internally to the machine before it indicates the alarm on the display panel. When
viewing the screen showing the alarm start/end times, the start time shows when the alarm was first
detected by the machine, and not when it was first displayed. The 'Alarm Delay After Acknowledge'
setting determines the number of minutes an alarm remains acknowledged before it returns to the active
mode. While an alarm is acknowledged, the plant alarm system is not activated, unless another alarm
occurs. The alarms can be acknowledged from any display panel, or from the Operator Interface Panel on
the machine itself.
The 'Alarm Override' function is a feature which is independent of the alarm setup, which allows certain
alarms to be temporarily disabled for a specified amount of time. Instructions on the use of this function
are given in Section 4.6 on Page 30. The alarm override is enabled automatically whenever a profile is
started, or it can be enabled when the setpoint is changed. The selected alarms will be disabled for the
specified amount of time, after which alarms return to function as per the alarm setup.
The following is a list and description of all the alarms that can occur on the Sentry system:
High Temperature: This alarm indicates that the actual temperature reading has climbed above the
temperature setpoint by 0.4 °F (0.222 °C) or more. This alarm cannot be disabled, and the machine will
start cooling and disable humidification as corrective measures. The 'Alarm Ranges' function can be used
to change the temperature at which an alarm will be activated.
Low Temperature: This alarm indicates that the actual temperature reading has dropped below the
temperature setpoint by 0.4 °F (0.222 °C) or more. Humidification is disabled while this alarm is active. The
'Alarm Ranges' function can be used to change the temperature at which an alarm will be activated.
High Humidity: This alarm indicates that the actual humidity reading has climbed above the humidity
setpoint by 4 %RH or more. Note: The machine performs all humidity control in relative humidity, thus it is
possible if the display panel is showing humidity in degrees wet bulb that there is a high humidity alarm
even though the wet bulb humidity appears to be lower than the setpoint. It is suggested that the
operator always display humidity in relative humidity to avoid confusion. The 'Alarm Ranges' function
can be used to change the temperature at which an alarm will be activated.
Low Humidity: This alarm indicates that the actual humidity reading has dropped below the humidity
setpoint by 4% RH or more. Note: The machine performs all humidity control in relative humidity, thus it is
possible if the display panel is showing humidity in degrees wet bulb that there is a low humidity alarm
even though the wet bulb humidity appears to be higher than the setpoint. The 'Alarm Ranges' function
can be used to change the temperature at which an alarm will be activated.
Dry Wick: This alarm only occurs if the sensor measures humidity in degrees wet bulb. This alarm does
not occur on ACI machines since they do not support this type of sensor. The alarm is generated if the
wet bulb humidity rises above the setpoint by more than 9 °F (5 °C).
Maintenance: This alarm is generated whenever the fan switch is turned off on the machine. It is meant
as an informational alarm to indicate that the machine is not running.
Sentry Control System 111