User`s manual

Tuning and Operating, Chapter 5
WATLOW Series 965 User's Manual
24
Auto/Man-Alarms
NOTE:
When the alarm
output is de-
energized, the NO
contact is open in
the alarm condition.
Press once -
Clear
a latched
and
corrected
alarm.
Using Alarms
The Series 965 has two alarm types, Process or Deviation. A process alarm
sets an absolute temperature. When the process exceeds that absolute tempera-
ture limit an alarm occurs. The process alarm set points may be independently
set high and low. Under the Setup Menu, select the type of alarm output with the
Ot2 parameter. PrA = Process Alarm Pr = Process alarm with no alarm
message displayed
A Deviation alarm alerts the operator when the process strays too far from set
point. The operator can enter independent high and low alarm settings. The
reference for the deviation alarm is the set point. Any change in set point causes
a corresponding shift in the deviation alarm. dEA = Deviation Alarm
dE = Deviation alarm with no alarm message displayed
Example: If your set point is 100°F/38°C, and a deviation alarm is set at +7°F/
4°C as the high limit, and -5°F/3°C as the low limit, the high alarm trips at 107°F/
41.6°C, and the low alarm at 95°F/35°C. If you change the set point to 130°F/
54.4°C, the alarms follow the set point and trip at 137°F/59°C and 125°F/51.6°C.
Under the Setup Menu, select the type of alarm output with the Ot2 parameter.
dEA = Deviation Alarm dE = Deviation alarm with no alarm message displayed
Both process and deviation alarms can be latching or non-latching. When the
alarm condition is removed a non-latching alarm automatically clears the alarm
output. You must manually clear a latching alarm before it will disappear.
Flashing "LO" or "HI" in the lower display indicates an alarm when Ot2 = PrA or
dEA. The lower display alternately shows information from the current parameter
and the "LO" or "HI" alarm message at one second intervals. The alarm output is
de-energized and the L2 LED is lit.
To clear an alarm…
• First correct the alarm condition, then…
• If the alarm is latching…
Clear it manually; press the A/M key once as soon as the process
temperature is inside the HSA parameter alarm limit.
• If the alarm is non-latching…
The alarm clears itself automatically as soon as the process
temperature is inside the HSA parameter alarm limit.
Figure 26 -
Alarm Display
Examples