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5. PILOT FLAME ESTABLISHING Period (PFEP):
a. Low Fire Switch opens.
b. Lockout Interlock opens (RM7800L/40L, EC7840L).
c. Ignition/pilot valve/intermittent pilot valve terminal is
not energized.
d. Early spark termination terminal is energized after
five seconds.
e. No flame is present at the end of PFEP.
f.
Main valve terminal is energized (RM7840G).
6. MAIN FLAME ESTABLISHING Period (MFEP):
a. Low Fire Switch opens.
b. Lockout Interlock opens (RM7800L/40L, EC7840L).
c. Ignition/pilot valve/intermittent pilot valve terminal is
not energized.
d. Main valve terminal is not energized.
e. No flame is present at the end of MFEP.
7. RUN Period:
a. No flame is present.
b. Lockout Interlock opens (RM7800L/40L, EC7840L).
c. Interrupted pilot valve terminal is energized.
d. Main valve terminal is not energized.
8. POSTPURGE Period:
a. Pre-Ignition Interlock does not close in five seconds
and opens after five-second time period (except dur-
ing VP testing).
b. Ignition/pilot valve/intermittent pilot valve terminal is
energized.
c. Main valve terminal is energized (except during VP
testing).
OPERATION
Sequence of Operation
The RM7800L/40L, EC7840L has the following operating
sequences, see Fig. 4, 5, 7, and 8. The RM7800L/40L,
EC7840L LED provide positive visual indication of the
program sequence: POWER, PILOT, FLAME, MAIN and
ALARM.
Initiate
The RM7800L/40L, EC7840L enters the INITIATE sequence
when the Relay Module is powered. The RM7800L/40L,
EC7840L can also enter the INITIATE sequence if the Relay
Module verifies voltage fluctuations of +10/-15 percent or
frequency fluctuations of +/-10 percent during any part of the
operating sequence. The INITIATE sequence lasts for ten
seconds unless the voltage or frequency tolerances are not
met. When the tolerances are not met, a hold condition is
initiated and displayed on the VFD for at least five seconds.
When the tolerances are met, the INITIATE sequence
restarts. If the condition is not corrected and the hold condition
exists for four minutes, the RM7800L/40L, EC7840L locks out.
Causes for hold conditions in the INITIATE sequence:
a. AC line dropout is detected.
b. AC line noise prevents a sufficient reading of the
line voltage inputs.
c. Low line voltage brownouts occur.
The INITIATE sequence also delays the burner motor starter
from being energized and de-energized from an intermittent
AC line input or control input.
RM7800L1087; RM7840G1022,L1075; EC7840L1014 RELAY MODULES WITH VALVE PROVING
Standby
The RM7800L/40L, EC7840L is ready to start an operating
sequence when the operating control determines a call for
heat is present. (Terminal 6, or Terminal 17 if Valve Proving is
required.) The burner switch, limits, operating control and all
microcomputer monitored circuits must be in the correct state
for the RM7800L/40L, EC7840L to continue into the
PREPURGE sequence.
Normal Start-Up Pre-Purge
The ST7800 purge timers provide 15 Pre-Purge timings
selectable from 2 seconds to 30 minutes:
a. The operating control (terminal 6, or terminal 17 for
valve proving), Running Interlocks, Pre-Ignition
Interlocks, Burner Switch, Run/Test Switch, Lockout
Interlocks and all microcomputer monitored circuits
must be in the correct operating state.
b. The blower motor output, terminal 5, is powered to
start the PREPURGE sequence. The firing rate
motor is driven to the high fire position (RM7800L/
40L, EC7840L). The PREPURGE timing does not
begin until the Lockout Interlock String and High Fire
Switch are both closed.
c. If Before, Split or Both Valve Proving tests are
selected (and demand input T17 is used), the
RM7800L/40L, EC7840L will sequence the main
valves to conduct the VP tests concurrently with Pre-
Purge (beginning at 10 seconds into the purge time).
d. The Pre-Ignition Interlock input must remain closed
throughout PREPURGE (except during VP testing);
otherwise, control returns to the STANDBY state
and holds (30 seconds) for the RM7840G or safety
shutdown occurs for the RM7800L/40L, EC7840L.
e. The Lockout Interlock or Running Interlock inputs
(interlock circuit including Airflow Switch) must close
by ten seconds after demand; otherwise, a recycle
to the beginning of PREPURGE for the RM7840G
will happen or a safety shutdown for the RM7800L/
40L, EC7840L occurs.
f.
When PREPURGE timing is complete, the firing rate
motor drives to the low fire position, RM7800L/40L,
EC7840L.
g. When the firing rate motor reaches low fire position,
the Low Fire Switch, terminal 18, input must be
energized before entering the Ignition Trial state.
Ignition Trials—Pilot Lighted System (Except VP
System with DSI)
1. Pilot Flame Establishing Period (PFEP):
To get pilot lighted system on VP system, Jumper 2 on
RM7800L/40L, EC7840L or Jumper 3 on RM7840G
must be removed. Default is direct spark ignition.
a. With the firing rate motor at the low fire position:
(1) The pilot valve and ignition transformer,
terminals 8, 10 and 21, are energized. The
RM7840G has an interrupted or intermittent pilot
valve, terminal 21, depending on the selection of
configuration jumper 2. The RM7800L/40L,
EC7840L has a 15-second interrupted pilot
valve, terminal 21. All of the RM7800L/40L,
EC7840Ls have a ten-second interrupted pilot
valve/ignition, terminal 8. If operating as Valve
17
66-1162—2
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