Honeywell 7800 Series Installation Instructions Manual page 25

STANDBY
INPUT &
OUTPUT
SIGNALS
STANDBY-
PURGE
POWER
POWER
PILOT
FLAME
MAIN
ALARM
IGNITION- T10
PILOT- T8
MAIN- T9
AIR VALVE-T5
FLAME PROVEN- T21
ALARM- T3
MOTOR POSITION- T12-T15 L/H/MOD
@ LOW FIRE INPUT- T18
LIMITS COMPLETE- T7
SF1 SPECIAL FUNCTION- T6
SF2 SPECIAL FUNCTION- T17
SF3 SPECIAL FUNCTION- T19
SF4 SPECIAL FUNCTION- T20
FLAME SENSED
High/Low Stepfire sequence is used when the application
requires the burner flame to be switched, on command,
between a Low Fire and a High Fire Run state.
Off/On Stepfire sequence is used when the application
requires the burner flame to be switched, on command,
between a Standby state and a Main Flame state.
Each DSI operating sequence has several states. See Table
9 for the state names, the text as shown on an S7800A
Keyboard Display Module, and a brief description of the
state purpose. All three sequences have the Standby state
in common.
WARNING
The user of the RM7888A is responsible for
providing the correct signal to each special
function input terminal and must make sure that
safety is not compromised if an incorrect special
function input is applied.
PV Return and MV Lo Fire
PILOT
PILOT- MAIN
IGNITION TRAIN
LAST 5- FUEL ON
IGNITION
INFINITE
SECONDS
0-INFINITE
TIME
1ST 10 SEC
POWER POWER
POWER
PILOT PILOT PILOT
FLAME FLAME FLAME
MAIN
L L L
Fig. 21. RM7888A Relay Module Pilot Sequuence timing diagram.
RELEASE TO
BURNER BURNER
FUEL VALVE MODULATION
FUEL VALVE
OPEN-PILOT
OPEN-PILOT
TIMEOUT TIMEOUT
LAST 5 TO RUN: 0 TO
1ST 10 SEC
INFINITE INFINITE SEC
POWER POWER
POWER
PILOT
PILOT PILOT
FLAME
FLAME FLAME
MAIN MAIN MAIN
L L MOD
Initiate State
The Initiate state will be entered when the RM7888A is
powered. The sequence will transition to the Standby state
after a ten second period. However, if any condition exists
that could prevent reliable operation of the RM7888A, the
sequence will remain in the Initiate state until the
condition is corrected. These conditions include the
detection of the loss of ac power, insufficient ac power
level, incorrect ac line frequency, and excess noise present
on the ac line. A ten second stabilization period occurs
after the condition is corrected before the sequence
transitions to the Standby state. Also, any condition that is
detected will remain annunciated for a minimum of five
seconds.
Standby State
Standby states for the DSI sequences are the same as
those for the Pilot sequences. See Pilot Configuration
Ignition Trials.
25
RM7888A 7800 SERIES RELAY MODULE
PV Return Only
PILOT RELIGHT DRIVE TO LOW
PILOT
AFTER 10 SEC
RELIGHT FIRE POSITION
WAIT FOR LOW
2 TO 5 SEC.
OFF FOR 5 SEC
(WITH 2-3 SEC.
5 TO INFINITE AT LOW
10 SEC
SEC
STABILIZE)
POWER
POWER
PILOT PILOT
FLAME FLAME
MAIN
L MOD L
RETURN
TO MAIN
TRAIN
FUEL ON
STATE
POWER
PILOT
FLAME
M9497A
32-00214—01