RM7800L1087; RM7840G1022,L1075; EC7840L1014 RELAY MODULES WITH VALVE PROVING
66-1162—2
18
Proving, Terminal 21 is Main Valve 2 only.
During PFEP, the Low Fire Switch must remain
closed. If it opens, a safety shutdown occurs.
(2) The Pre-Ignition Interlock input is ignored
throughout the Ignition Trial state.
b. Flame must be proven by the end of the ten-second
PFEP (four if JR1 is clipped) to allow the sequence
to continue. If flame is not proven by the end of
PFEP, a safety shutdown occurs.
c. After five seconds, the ignition, terminal 10, is
de-energized for early spark termination.
2.
Main Flame Establishing Period (MFEP):
a. Terminal 9 (and 21 in VP mode) is energized when
the presence of flame is verified at the end of a 10-
second Pilot Flame Establishing Period (PFEP)
(four seconds if JR1 is clipped).
b. Terminal 8 is turned off 10 seconds after Terminal 9
(and Terminal 21) is energized.
c. Terminal 21 action demand on Terminal 6 (without
Valve Proving Function):
(1) RM7800L/40L, EC7840L: De-energized
15 seconds after Terminal 9 is energized.
(2) RM7840G:
(a) Not turned off, Intermittent pilot, or
(b)15 seconds after Terminal 9 is energized and
JR2 is clipped, or
(c)30 seconds after Terminal 9 is energized and
Terminals 5 and 19 are jumpered and jumper
JR2 is clipped.
Ignition Trials—Valve Proving with DSI System
1.
Demand connected to Terminal 17:
— JR2 Intact on RM7800L/40L, EC7840L
— JR3 Intact on RM7840G
a. Ignition, Main Valve 1 and Main Valve 2, Terminals
10, 9, and 21 turn on together.
b. Flame must be proven at the end of the 4 second
Main Flame Establishing Time.
c. Ignition, Terminal 10 is turned off. System now in
Run.
d. If Flame is not proven, safety lockout occurs.
Run
1.
A ten-second stabilization period occurs at the
beginning of the RUN period.
2.
The firing rate motor releases to modulation.
3.
The RM7800L/40L, EC7840L is now in RUN and
remains in RUN until the controller input, terminal 6,
opens (terminal 17, on VP applications), indicating that
the demand is satisfied or a limit opened.
Postpurge
The RM7800L/40L, EC7840L provides a programmable
(default is 15 seconds) POSTPURGE following the
completion of the RUN period. The blower motor output is
powered to drive all products of combustion and any
unburned fuel from the combustion chamber. It also supplies
combustion air to burn fuel being purged from the fuel line
downstream of the fuel shutoff valve.
1.
The main fuel valve and intermittent pilot valve,
Terminals 9 and 21, are de-energized and the firing rate
motor is commanded to the low fire position to begin the
POSTPURGE period.
2.
The Pre-Ignition Interlock closes within the first five
seconds after the demand opens.
3.
If Valve Proving option—After Split or Both have been
selected, then the Valve Proving test will be conducted
concurrent with Postpurge. If Postpurge timing remains
after the Valve Proving test is completed, the Postpurge
timing will complete before the RM7800/40G,L go into
standby.
Table 7. Sequence Timing for Normal Operation.
* STANDBY and RUN can be an infinite time period.
** PURGE determined by which ST7800A purge card is selected.
a
The MFEP is determined by which terminal is used, configuration jumper selected or jumper wire added.
See Fig. 2, 3, 4, 6, and 7.
b
If DSI is Enabled on a VP application (JR2 intact on RM7800L/40L, EC7840L or JR3 intact on RM7800/40G) then Ignition (ter-
minal 10) and MV
1
(terminal 9), and MV
2
(terminal 21) are energized together. After 4 seconds terminal 10 shuts off, and sys-
tem goes to Run.
c
If DSI is disabled on a VP application then MFEP is 10 seconds.
d
Default is 15 seconds. Can be programmed as long as 66 minutes.
Device
Initiate Standby Purge
Flame Establishing
Period
Run
Post-
Purge
Timing
d
Interlock Circuits
Firing
Rate
Circuit
Approval
Code
Bodies
Pilot
Main
a, c
RM7840G 10 sec. *
**
4 or 10
sec.
10, 15 sec. or
intermittent
b
*
15 sec. Pre-Ignition,
Running, Low Fire
4-wire
modulating
UL/CSA
Modulating
RM7800L/
RM7840L/
EC7840L
10 or 15 sec.
b
Pre-Ignition,
Lockout, High and
Low Fire
FM/IRI
Modulating
