Watlow Series 945 High/Low Limit Control - Manual (Page 7)

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WATLOW Series 945 High/Low Limit User's Manual
Alarms
Using Alarms
The Series 945 has two alarm types, Process or Deviation. A Process alarm
sets an absolute temperature when the process exceeds that absolute temper-
ature limit.
A Deviation alarm alerts the operator when the process strays too far from set
point. The reference for the deviation alarm is the process value.
Both Process and Deviation alarms can be latching or non-latching. The
operator must manually reset a latching alarm before the alarm will reset.
The operator must also remove the condition that created the alarm. When the
operator removes the condition causing the alarm, a non-latching alarm
automatically resets the alarm output.
Flashing 'LO" or "HI" in the lower display indicates an alarm. The Lower
display alternately shows information from the current parameter and the "LO"
or "HI" alarm message at one second intervals. The audible alarm (Output 1) is
energized and the alarm relay outputs are de-energized and the A1 and A2
LED are lit.
To silence the audible alarm (Output 1)...
•
Press the alarm clear button once.
To clear an alarm (Output 2 or Output 3)…
•
First correct the alarm condition, then…
• If the alarm is latching…
Clear it manually; press the ALARM CLEAR key twice as soon as
the process temperature is inside the alarm limit according to the
HYS parameter.
• If the alarm is non-latching…
The alarm will clear itself automatically as soon as the process
temperature is inside the alarm limit according to the HYS parameter.
Press twice -
Clear
a latched
and
corrected
alarm.
Figure 11 -
Alarm Display
Examples
CAUTION:
An alarm display will
be masked by an
error condition or
when the control is
in the Calibration or
Setup Menus.
AL1 - Indicates Sonalert Output
AL2 - Indicates Alarm 2 Outputs 2 & 3