Specifications
MONITOR
HEATING SYSTEMS
Section
1:
Description
1-35
Revolution
control
of
combustion
blower
motor
IC4
TRIAC
L
fSfj
1
Hole
1C
01
JT
Fig.
1-1
-o
5V
microprocessor
As
shown
in
Fig.1-1,
the
current-carrying
ratio
for the
combustion blower motor shall
be
performed
by the
phase
control,
TRIAC,
Q1.
The
combustion blower motor
has a
built-in
hole
1C
of
which input signal
is
entered
to the
microproces-
sor
through
the
comparator IC8.
The
hole
1C
outputs
the
pulse signal
by 6
pulse
ev-
ery
one
revolution
of the
motor.
The
microprocessor
counts this pulse
signal
to
obtain
the
number
of
pulse, frequency
per one
second,
and
then compute
the
motor
revolution
-per
one
minute
by
this
frequen-
cy.
In
order
to
achieve
the
target control revolutions
shown
in
Table 1-1/1-2, Page 4/8,
the
current-carry-
ing
ratio
to the
motor shall
be
controlled
by
TRIAC,
Q1
to
make
the
revolution
of the
combustion blower
motor
constant.
If
the
revolution
of the
combustion blower
has
slowed down
to
less than 1200
(rpm),
an
abnormal
revolution
will
be
sensed
and
then
the
heater opera-
tion
will
be
stopped
indicating
the
error code
of
(EOS)
in the
display window.