TENNEY ENVIRONMENTAL
-
ALARM AND SHUTDOWN CIRCUIT
1
A
comprehensive alarm and shutdown circuit may be provided for multiple protection against
product
overtunder temperature and chamber over temperature. The sensor utilized for
temperature measurement and the Heat Limiter Fuse are normally placed at the plenum in the
downstream airflow. This is the most responsive area of the chamber.
Chamber Over Temperature Protection: The following device is used,
1.
Heat Limiter (HL)
-
-
Temperature Actuated Fuse
(Standard)
Product
OverIUnder Temperature Protection: The following optional device may be used.
With this option, a
100
ohm platinum RTD
IS
utilized for temperature measurement.
1.
Watlow
93
Controller
-
-
TempGard IV Feature
-
HighlLow Limits
(Optional)
WARNING! When Master Contactor ICON is deenergized due to ANY alarm condition
described below, power is only
removed
from the conditioning control circuitry. The
instrumentation and alarm circuitry will still be energizedl
For any questions concerning the operation of any of the controllers described below, please
reference the appropriate user manual located in the Supplemental Instructions Section.
CIRCUIT
OPERATIONS<
'
~)
Normal Conditions:
When chamber temperature is within the selected setpoints the switch (green) ON light is
illuminated and the Master Contactor ICON is energized. The contacts of
ICON provide
power to the conditioning control circuitry. (With the optional
alarnl buzzer 1 silence switch or
TempGard
IV feature, the NORMAL light 2LT will illuminate. When either of these optional
features are used, the main control switch will not be equipped with any integral lights.)
Note:
A
spare set of ICON contacts are provided for the customer's closure. It is
recommended that these contacts, wired to terminal blocks
#14
&
#15,
be used to energize an
active heat load if utilized.
Ovened Heat Limiter:
When a predetermined high temperature limit is reached and the Heat Limiter Fuse (which
looks like a regular fuse) opens. Master Contactor
ICON will deeneraize alona with the
conditioning control
circhitj. The switch OVERTEMP light will illuminate and the switch ON
light will extinguish. (With the optional alarm buzzer
I
silence switch feature, both the red
chamber
OVERTEMP
light
~LT
and red ALARM light
4LT
will immediately illuminate, be alarm
buzzer will sound, and the NORMAL light will extinguish.) When the Heat Limiter Fuse opens,
it be replaced.
WARNINGI
When replacing the Heat Limiter Fuse, make sure all power
IS
completely
disconnected from the chamber. Open the
closest main power disconnect and pull the plug (if
,-
1
provided) from the outlet.
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