Watlow Series 92 - Manual (Page 10)

10
WATLOW Series 92 User's Manual
1. Automatic Reset (Integral) - Used in proportional
control systems to automatically pick up any system
droop. This action may be adjustable or fixed, and
adjusts the output level to obtain agreement be-
tween actual process temperature and controller set
point.
2. Automatic Reset on Power Loss - The limit
control does not recognize the power outage as a
limit condition. When power is restored, the output
will energize automatically as long as a temperature
limit condition does not exist.
3. Anti Reset - Inhibits reset action when the actual
process temperature is outside the proportional
band.
4. Cycle Time - Time interval between consecutive
turn ons.
5. Manual Reset or Offset - Adjustment used in
control systems to offset any temperature droop
and obtain agreement between actual process
temperature and controller set point.
6. ON/OFF - The output is turned full ON below set
point and stays turned on until the process tem-
perature reaches set point, then the controller turns
the output full OFF. At this point, depending on the
design of the thermal system, the process tempera-
ture overshoots the set point temperature by some
degree. As the load cools down below set point (an
amount equal to the switching sensitivity or differen-
tial) the output is once again turned full ON.
7. Proportional Band - In a straight time proportional
control system when the actual process tempera-
ture is below set point and outside the proportional
band limit, 100% power is applied to the load.
When the actual process temperature is above set
point and outside the proportional band limit, 0%
power is applied to the load.
When the actual process temperature is within the
proportional band, the controller will proportion the
amount of power applied to the load, 0 to 100%.
Glossary
8. Switching Sensitivity or Differential - The output
will de-energize when the actual temperature
reaches the set point temperature. The switching
sensitivity or differential is the drop in temperature
required to re-energize the output.
9. Temperature Droop - Phenomenon that occurs in
a proportional control system without reset. As the
proportional band is increased, the average process
temperature may drop to a point that is not the set
point temperature. This action takes place even
though the load has stabilized.
10. Temperature Oscillation or Hunting - Occurs
when the proportional band is too narrow or the
system is upset by some outside source. The
actual process temperature is not controlled within
the proportional band on its extreme temperature
excursions.
Load temperature may never stabilize. Control is
either full ON or full OFF, not within the proportional
band.
11. Variable Time Base - When the time base varies
upon load demand. The Series 92 at 50% power
level passes three AC cycles on and three AC
cycles off.
12. Zero Switching - Load is activated only during the
time period that the sine wave is going through
zero. This eliminates RFI and EMI radiation
(applies to solid state outputs only).
13. or - Musical Notes are used to alert you to
important details.
14. - The Warning symbol ((lightning bolt)
alerts you to a "WARNING", a safety hazard which
could affect
you and the equipment.
15. - The Caution symbol (exclamation
point) alerts you to a "CAUTION", a safety or
functional hazard which could affect
your equipment
or its performance.