Honeywell 7800 Series Manual page 21

TABLE 5—PILOT CONFIGURATION OPERATING SEQUENCE STATES (Continued).
Pilot S7800 Keyboard
Configuration Display Module
State Name Displayed Text
—
@Low 10 Sec
Pilot Relight PVHOLD IGN 00:ss
Low Off 5 Sec. PVHOLD IGN 01:00
Drive to Low PVHOLD IGN 02:00
PILOT CONFIGURATION SEQUENCE OF
OPERATION
WARNING
The user of the RM7888A is responsible for pro-
viding the correct signal to each special function in-
put terminal and must make sure that safety is not
compromised if an incorrect special function input
is applied.
INITIATE
The RM7888A enters the INITIATE sequence when the
Relay Module is powered. The RM7888A also enters 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 volt-
age or frequency tolerances are not met. When the toler-
ances are not met, a hold condition will be initiated and will
be displayed on the Keyboard Display Module 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 RM7888A
will lock out. Causes for hold conditions in the INITIATE
sequence are:
• AC line dropout is detected.
• AC line frequency error caused by using a 60 Hz
device on an 50 Hz line, or vice versa.
• AC line noise that can prevent a sufficient reading of
the line voltage outputs.
• Brownouts caused by a low line voltage.
RUN When special function input terminal 20 is off, relay module will
command a Low Fire motor position.
RUN When the Low Fire input becomes energized for a continuous time
period of 10 seconds, the sequence will leave the Release to
Modulation state and proceed to the Pilot Relight state (PV Return
sequence only).
Re-establish the pilot flame and drop the main flame. Display indicates
elapsed time in this timed state (PV Return sequence only).
Wait for the Low Fire input signal to become de-energized for a
continuous period of five seconds and then proceed to the Main Train
Fuel On state after driving back to the Low Fire position. Display
indicates that sequence is in Pilot Hold State type 1 = Waiting for Low
Off 5 Sec.
Commands the low fire motor position and waits until the Low Fire
input becomes energized before proceeding to the Main Train Fuel On
state. Display indicates that sequence is in Pilot Hold State type
2 = Waiting for Low Fire On.
Purpose of State
STANDBY
The Standby states include Standby-Off, Standby-Purge,
Standby-Control Cool, and Standby-Low Combustion Air
Only, and Standby-Hold. All Standby states command the
ignition, pilot and main off and will lockout if the feedback
signals indicate that one of those terminals is energized.
The Flame Proven output will be commanded off without
regard to the current Flame Sensed signal. After the first
three seconds of Standby, if the Flame Sensed signal indi-
cates flame, the special function inputs will be ignored, the
Air Valve will be commanded off and the motor position
commanded to Low Fire. The alarm output will be com-
manded off.
The Standby state selected is based on the state of special
function inputs 1, 2, 3 and 4 (terminals 6, 17, 19 and 20).
A three-second transition period runs when the Standby
state is entered. This time period allows enough time for the
master system controller to set up the desired combination of
special function input signals so when the time period ex-
pires, the required motor position command and air valve
output status are commanded. During the time period, the
motor control is commanded to the Low Fire position, the
Air Valve is commanded off, the special function input
terminals are ignored, and the safety loads (Ignition, Pilot
and Main Valve) are commanded off immediately upon
entering Standby.
When special function 1 is energized, a request for burner
operation is in effect, the Air Valve will be commanded off
and the LowFire motor position commanded. In this case,
special functions 2, 3, and 4 are ignored. The burner will
sequence to the Pilot Ignition state as soon as the Low Fire
input and the Limits Complete input are energized.
21
RM7888A
OPERATION
65-0175