Sequence Of Operation - Honeywell R7120M 7800 Serie Instructions D'installation

R7120M 7800 SERIES RELAY MODULES
e. Internal system fault occurred.
f. Purge card is removed.
g. Purge card is bad.
5. MAIN FLAME ESTABLISHING PERIOD (MFEP)
a. Airflow lockout feature is enabled and the airflow
switch opens.
b. Ignition terminal is energized.
c. Ignition/pilot valve terminal is not energized.
d. Main valve terminal is not energized.
e. Loss of flame signal.
f. Internal system fault occurred.
g. Purge card is removed.
h. Purge card is bad.
6. RUN PERIOD
a. No flame present (JR2 removed).
b. Airflow lockout feature is enabled and the airflow
switch opens.
c. Main valve terminal is not energized.
d. Internal system fault occurred.
e. Purge card is removed.
f. Purge card is bad.
g. Ignition terminal is energized.
SERVICE NOTE:
Be sure to perform the System Checkout beginning on page
15 before leaving the equipment for normal cycle operation.
Safety Shutdown Sequence:
1. A safety shutdown occurring during Initiate or Standby
will lockout the R7120 (prevent it from starting) indicated
by an alarm.
2. A safety shutdown occurring during purge results in the
blower motor terminal 8 being de-energized and the
system will lockout indicated by an alarm.
3. A safety shutdown during the ignition trial period (pilot or
main) or Run (if JR2 clipped), all fuel valves and the
ignition (if on) will be de-energized and the system will
lockout indicated by an alarm. The R7120 will complete
the programmed post purge before the blower motor
terminal 8 is de-energized. If no post purge is pro-
grammed, the R7120 will shut off the blower motor ter-
minal 8.
Manual reset is required following any safety shutdown.
Manual reset may be accomplished by pressing the push
button on the device or pressing the remote reset wired
through an attached display or S7820 remote reset module.
Interrupting power will cause electrical resets, but does not
reset a safety lockout condition.
OPERATION

Sequence of Operation

The R7120M has the operating sequences listed below. The
R7120M LED provide positive visual indication of the program
sequence: POWER, PILOT, FLAME, MAIN and ALARM.
Initiate
The R7120M Relay Module enters the INITIATE sequence
when the relay module is initially powered. The R7120M can
also enter the INITIATE sequence if the relay module verifies
voltage fluctuations of +10/-15% or frequency fluctuations of
66-1193EF—01
±10% during any part of the operating sequence. The
INITIATE sequence lasts for ten seconds unless the voltage or
frequency tolerances are not met. When not met, a hold
condition is initiated and displayed on the optional KDM for at
least five seconds; when met, the INITIATE sequence
restarts. If the condition is not corrected and the hold condition
exists for four minutes, the R7120M locks out. Causes for hold
conditions in the INITIATE sequence:
1. AC line dropout detection.
2. AC line noise that can prevent a sufficient reading of the
line voltage inputs.
3. Low line voltage brownouts.
The INITIATE sequence also delays the burner motor starter
from being energized and de-energized from an intermittent
AC line input or control input.
Standby
The R7120M is ready to start an operating sequence when
the operating control input determines a call for heat is
present. The burner switch, limits, operating limit control and
all microcomputer-monitored circuits must be in the correct
state for the relay module to continue into the PREPURGE
sequence.
Normal Start-Up Prepurge
The R7120M Relay Module provides PREPURGE timing,
selectable with ST7800 Purge Timer cards, from two seconds
to thirty minutes with power applied and the operating control
indicating a call for heat.
1. The Airflow Interlock, burner switch, Run/Test switch
and all microcomputer-monitored circuits must also be
in the correct operating state.
2. The motor output, terminal 8, is powered to start the
PREPURGE sequence.
3. The Airflow Interlock input closes ten seconds into
PREPURGE or within the specified purge card timing;
otherwise, a recycle to the beginning of PREPURGE or
lockout occurs, depending on how the Airflow Switch
selectable jumper (JR3) is configured.
Ignition Trials
1. Pilot Flame Establishing Period (PFEP):
a. When the PFEP begins:
(1) The pilot valve and ignition transformer,
terminals 3 and 4 are energized.
(2) Flame must be proven by the end of the ten sec-
ond PFEP (four seconds if Configuration Jumper
JR1 is clipped) to allow the sequence to con-
tinue. If a flame is not proven by the end of
PFEP, a safety shutdown occurs.
2. Main Flame Establishing Period (MFEP):
a. After PFEP, and with the presence of flame,
the main fuel valve, terminal 5, is powered. If a
flameout occurs, the relay module locks out within
0.8 or 3 seconds, depending on the Flame Failure
Response Time (FFRT) of the amplifier.
b. The R7120M1019 has a ten second MFEP. After the
Ignition Trials, the interrupted ignition/pilot valve,
terminal 4 is de-energized. If a flameout occurs, the
relay module recycles (locks out if jumper JR2 clipped)
within 0.8 or 3 seconds, depending on the Flame
Failure Response Time (FFRT) of the amplifier.
8