14
EC7830, RM7830A,EC7850A,RM7850A 7800 SERIES RELAY MODULES
66-1092—2
6. PILOT STAB. PERIOD
a.
Lockout Input opens during PILOT STAB.
b.
Airflow Switch opens during PILOT STAB.
c.
Low Fire Switch opens (EC/RM7850A).
d.
No flame is present.
e.
Ignition terminal is energized.
f.
Pilot valve/intermittent pilot valve terminal is not
energized.
g.
Main valve terminal is energized.
h.
Internal system fault.
i.
Purge card is removed.
j.
Purge card is defective.
7. MAIN TRIAL PERIOD
a.
Lockout Input opens during MAIN TRIAL.
b.
Airflow Switch opens during MAIN TRIAL.
c.
Low Fire Switch opens (EC/RM7850A).
d.
No flame is present.
e.
Ignition terminal is energized.
f.
Pilot valve/intermittent pilot valve terminal is not
energized.
g.
Pilot valve is energized during MAIN TRIAL
stabilization.
h.
Main valve terminal is not energized.
i.
Internal system fault.
j.
Purge card is removed.
k.
Purge card is defective.
8. RUN Period.
a.
No flame is present.
b.
Lockout Input opens.
c.
Ignition/interrupted pilot valve terminal is
energized.
d.
Main valve terminal is not energized.
e.
Internal system fault.
f.
Purge card is removed.
g.
Purge card is defective.
h.
Airflow Switch Input opens.
9. POSTPURGE Period
a.
Ignition/pilot valve/intermittent pilot valve terminal
is energized.
b.
Main valve terminal is energized.
c.
Internal system fault.
d.
Purge card is removed.
e.
Purge card is defective.
OPERATION
Sequence of Operation
The relay modules have the operating sequences listed
below; see Fig. 3 and 4. The relay module LED provide
positive visual indication of the program sequence: POWER,
PILOT, FLAME, MAIN and ALARM.
Initiate
The relay module enters the INITIATE sequence when the
relay module is initially powered. The relay module 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 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 relay module locks out.
Causes for hold conditions in the INITIATE sequence:
a. AC line dropout detection.
b. AC line noise that can prevent a sufficient reading of the
line voltage inputs.
c. 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 relay module 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 PURGE
sequence.
Normal Start-Up Purge
The relay module provides PURGE timing selectable from two
seconds to thirty minutes with power applied and the
operating control indicating a call for heat.
1. The Preignition Interlocks, Limits and Burner Control,
Run/Test Switch, Airflow Switch Input, Lockout Input,
and all microcomputer-monitored circuits must also be
in the correct operating state.
2. The blower motor output, terminal 5, is powered to start
the PURGE sequence. The firing rate motor is driven to
the high fire position (EC/RM7850A). The PURGE
timing does not begin until the Airflow Switch Input and
High Fire Switch (EC/RM7850A) are both closed.
3. The Preignition Interlock Input must remain closed
throughout PURGE or a safety shutdown occurs.
4. The Airflow Switch Input must close by ten seconds into
PURGE or a safety shutdown occurs.
5. After the firing rate motor reaches the PURGE rate
position and PURGE timing is completed, the motor
drives to the low fire position (EC/RM7850A).
Ignition Trials
1. Preignition: With the firing rate motor at the low fire
position (EC/RM7850A), the ignition transformer,
terminal 10, is energized for three seconds.
2. First Safety Time (SAFETY1):
a.
With the firing rate motor at the low fire position
(EC/RM7850A):
(1) The pilot valves and ignition transformer,
terminals 8, 10 and 21, are energized.
Terminal 8 is an interrupted pilot valve and
terminal 21 is an intermittent pilot valve.
(2) During SAFETY1, the Low Fire Switch Input
must be closed. If it opens, a safety
shutdown occurs (EC/RM7850A).
(3) The Preignition Interlock Input is ignored
during SAFETY1, PILOT STAB., MAIN
TRIAL, RUN and POSTPURGE.
b.
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.
3. Pilot stabilization (PILOT STAB.): With flame proven, the
ignition, terminal 10, is de-energized. The duration of
this state is five seconds.