Operation - Honeywell 7800 Series Manual

7800 SERIES RM7830A, RM7850A RELAY MODULE
RUN/TEST SWITCH
Fig. 15. Selectable site-configurable jumpers.

OPERATION

Sequence of Operation
The RM7830A or RM7850A Relay Module has the following
operating sequences, see Fig. 16 and Table 5.
Initiate
The RM7830A or RM7850A
enters the INITIATE
sequence when the Relay
Module is powered. The RM7830A or RM7850A 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 two seconds unless the voltage
or frequency tolerances are not met. When the tolerances are
not met, a hold condition will be initiated and will be displayed
on the display for at least five seconds. When the tolerances
are met, the INITIATE sequence will restart. If the condition is
not corrected and the hold condition exists for four minutes,
the RM7830A or RM7850A will lockout. Causes for hold
conditions in the INITIATE sequence:
a. AC line dropout is detected.
b. AC line frequency error caused by using a 60 Hz device
on a 50 Hz line, or vice versa.
c. AC line noise that can prevent a sufficient reading of
the line voltage inputs.
d. Brownouts caused by a low line voltage.
e. AC line phase is incorrect. L1 and N are miswired.
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 RM7830A or RM7850A
is ready to start an
operating sequence when
the operating control determines a call for heat is present.
The burner switch, limits, operating control and all
microcomputer monitored circuits must be in the correct state
for the RM7830A or RM7850A to continue into the PURGE
sequence.
65-0222
SELECTABLE CONFIGURATION
JUMPERS
M7701
INITIATE 00:10
Diagnostic Info
STANDBY HOLD: T7
Total Cycles 132
Normal Start-Up
Purge
The RM7830A or RM7850A
provides a PURGE timing selectable from
two seconds to 30 minutes with power applied and the Relay
Module operating control indicating a c all for heat:
a. Preignition Interlocks, Limits and Burner Control, Run/
Test Switch, Airflow Switch Input, Lockout Input and all
microcomputer monitored circuits must be in the correct
operating state.
b. The blower motor output, terminal 5, is powered to start
the PURGE sequence. The firing rate motor is driven to
the high fire position (RM7850A). The PURGE timing
does not begin until the Airflow Switch Input and High
Fire Switch (RM7850A) are both closed.
c. The Preignition Interlock input must remain closed
throughout PURGE; otherwise, a safety shutdown
occurs.
d. The Airflow Switch Input must close by ten seconds into
PURGE; otherwise, a safety shutdown occurs.
e. After the firing rate motor reaches the PURGE rate
position and PURGE timing is completed, the firing rate
motor will drive to the low fire position (RM7850A).
f. When the firing rate motor reaches the low fire position,
the Low Fire Switch, terminal 18, input must be
energized before entering the Ignition Trial state
(RM7850A).
Ignition Trials
a. Preignition: With the
firing rate motor at
the low fire position (RM7850A), the ignition
transformer, terminal 10, is energized for 3 seconds.
b. First Safety Time
M1994
(SAFETY1):
1. With the firing
rate motor at the
low fire position (RM7850A):
a. The pilot valves and ignition transformer,
terminals 8, 10 and 21, are energized.
Terminal 8 is an interrupted pilot valve
whereas terminal 21 is an intermittent pilot
valve.
b. During SAFETY1, the Low Fire Switch Input
must be closed. If it opens, a safety
shutdown occurs (RM7850A).
c. The Preignition Interlock Input is ignored
during SAFETY1, PILOT STAB., MAIN
TRIAL, RUN and POSTPURGE.
2. Flame must be proven by the end of three or five
seconds to allow the sequence to continue. A
safety shutdown occurs if there is no flame.
c. Pilot stabilization
(PILOT STAB.): With
flame proven, the
ignition, terminal 10
is de-energized. The
duration of this state is 5 seconds.
d. Main Trial
(MAIN TRIAL):
1. The MAIN
TRIAL time is
selectable as
M1995
three or five seconds. After PILOT STAB., and
with the presence of a flame, the main fuel valve,
terminal 9 is powered. If a flame out occurs, the
Relay Module will lockout within 1 or 2 seconds,
depending on the Flame Failure Response Time
(FFRT) of the amplifier. Thus, second safety time
is defined to be MAIN TRIAL time plus FFRT of
the amplifier.
20
PURGE 00:30
Total Hours 396
M1996
PREIGNITION
Fault History
M3923
SAFETY 1 00:05
Fault History
M3924
PILOT STAB.
Fault History
M3925
MAIN TRIAL 00:05
Flame Signal 2.7V
M3926