USING
THE
17400
DIGVAL
TEMPERATURE
CONTROL
(WITH THE
16910
MOD
TEMPERATURE LIMIT)
The 17400 Temperature Control
ModulatingHigh Temperature Limit to preve
cases, cause fires. These instru
all Samuel Jackson Dryaire Heaters.
eaters can be used with the 16910
s
which can harm cottonquality and,
in
extreme
delines for use of this control arrangementwith
The 17400 control assembly uses two H ure controllers. The controller on
the k& as you face the control ntroller. The controller on the
.t$&j
is
designatedthe "HIGH LIMIT" controller. ts thermocouple temperature sensor
mountedDOWNSTREAM of th LIMIT controller has its thermocouple
mountedupstream of the mixpoint. The P atches the temperature after cotton has mixed
with the air.
If
wet cotton is fed into the system, the air is cooled and the PRIMARY controller signals the HIGH
LIMIT controller that more heat is needed to compensate for this cooling. The HIGH LIMIT controller operates
the burner's gas valve to supply this heat, but
in
no
case
will the temperature be permitted to exceed the limit
which the ginner
has
previouslyspecified.
If
dry cotton isfed into
the
system the reverse occurs.
In
the case of
achoke or large air leak, the HIGH LIMIT controller may not be able to contain the temperature within the
specified limits and
it
will then shut down the burner to prevent a fire (with an appropriate
ERROR
code on
burnerswith microprocessorcombustioncontrols).
NORMAL OPERATION PROCEDURE
There is a spring return selector switch located below the PRIMARY controller with a "1" on the right and a
"0"
on
the left. These are symbols for START-STOPoperations. Turn the switchto "1" and release it to start the burner.
Turn the switch to
"0"
to shut down the burner. After turning the switch to
"l",
please notethat there is a preset
time delay to allow the burner head and piping to be purged with air. Following this delay, ignition is tried and
should occur immediately. If ignition is not successful and your model has microprocessor combustion
controls, observe the STATUS light to see if
it
isflashing.
If
it
is, go to the burner's control cabinet and note the
ERROR/ALARM code displayed on the local panel. There is a decal at the control cabinet and a page in each
service manual explaining the numbers.
It
will be necessary
to
press the
RESET
button on the burner's local
panel in order to clear the
ERROR
and rest
r.
In
the case of failure in ignitionor failure
in
operation,
the burner will automatically attempt to
r
itself for a maximum of three attempts. Neither digital
temperaturecontroller
will
come on until flame has been established
in
the burner. This is to prevent the highly
responsivecontrolsfrom "winding up" during
t
ir
purge delay time and causingthe burner to come on with a
roar. When they do energize, the controllers take 12 seconds to perform self-check operations and then
display
the
temperatures.
There are four temperatures displayed at all times du g burner operation. The PRIMARY control on the left
shows two and the HIGH LIMIT control on the right shows
two
as well. The lower display on the PRIMARY is the
temperaturewhich the ginner sets and is the only one he will adjust under normal circumstances. It is the
temperaturedesired after the mixpoint.
It
is raised and lowered with the orange buttons below
it.
The upper
displayshows the actual temperature being by th thermocouple. On the HIGH
LIMIT
controller, the lower display is the tempera ntrol is feeding it (See "Principle of
Operation"Section). The upper display on the right is the actualtemperature beforethe mixpoint. By observing
the upper display on both controllers,
it
is possible to estimate the wetness of the incoming cotton as they
will
move farther apart as the cotton gets wetter.
h the
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