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Principal Technical Features; Sequence Of Operation - Honeywell 7800 Series Installation Instructions Manual

Valve proving primary relay modules
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PRINCIPAL TECHNICAL
FEATURES
The RM7898 provides all customary flame safeguard
functions as well as significant advancements in safety,
annunciation, and system diagnostics.
Safety Shutdown (Lockout) Occurs
if:
1. INITIATE PERIOD
a. Purge card is not installed or removed.
b. Purge card is bad.
c. Configuration jumpers have been changed (after
200 hours)—Fault Code 110.
d. AC line power errors occurred. See "Operation"
on page 17.
e. Four minute INITIATE period has been exceeded.
2. STANDBY PERIOD
a. Airflow lockout feature is enabled and the airflow
switch does not close after ten seconds or within
the specified purge card timing.
b. Flame signal is detected after 240 seconds.
c. Ignition/pilot valve terminal is energized.
d. Main valve 1 or 2 terminal is energized.
e. Internal system fault occurred.
f.
Purge card is removed.
g. Purge card is bad.
h. Pre-Ignition Interlock open.
3. PREPURGE PERIOD
a. Airflow lockout feature is enabled and the airflow
switch opens.
b. Ignition/pilot valve terminal is energized.
c. Main valve 1 or 2 terminal is energized.
d. Internal system fault occurred.
e. Purge card is removed.
f.
Purge card is bad.
g. Flame signal is detected for 30 seconds.
h. Pre-Ignition Interlocks open during standby.
i.
VPS test failure (if Before, Both, or Split are
selected).
j.
Both T6 and T17 demands energized.
k. T17 energized but Valve Proving is not set up.
4. PILOT FLAME ESTABLISHING PERIOD (PFEP).
a. Airflow lockout feature is enabled and the airflow
switch opens.
b. No flame signal at end of PFEP.
c. Ignition/pilot valve/intermittent pilot valve ter-
minal is not energized.
d. Main valve terminal is energized (unless DSI
Select Mode enabled).
e. Valve terminal 21 is not on.
f.
Internal system fault occurred.
g. Purge card is removed.
h. 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(s) are not energized.
e. Main valve 2 terminal is not energized.
f.
Loss of flame signal.
g. Internal system fault occurred.
RM7898A 7800 SERIES VALVE PROVING PRIMARY RELAY MODULES
h. Purge card is removed.
i.
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. Interrupted pilot valve terminal is energized.
d. Main valve terminal is not energized.
e. Internal system fault occurred.
f.
Purge card is removed.
g. Purge card is bad.
h. Ignition terminal is energized.
7. POST-PURGE
a. Pre-Ignition Interlock does not close in 5 sec-
onds.
b. Ignition/Pilot Valve terminal is energized.
c. Main Valve(s) terminal is energized.
d. Internal System Fault.
e. Purge Card is removed.
f.
Purge Card is bad.
g. VPS Test failure (if Both, Split or After is selected).
OPERATION

Sequence of Operation

The RM7898 has the operating sequences listed below;
see Fig. 5 and 6. The RM7898 LED provide positive visual
indication of the program sequence: POWER, PILOT,
FLAME, MAIN and ALARM.
Initiate
The RM7898 Relay Module enters the INITIATE sequence
when the relay module is powered. The RM7898 can also
enter the INITIATE sequence if the relay module verifies
voltage fluctuations of +10/-15% or frequency
fluctuations of ±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 RM7898 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 RM7898 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. (Terminal 17 input initiates the
RM7898 VPS feature.)
17
32-00209—03

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