Honeywell 7800 Series Manual page 20

RM7888A
OPERATION
Pilot Configuration Operating Sequence.
The Pilot Configuration Operating Sequence has two
distinct operating sequences that are entered from the Stand-
by/Standby Purge states. The sequences are:
a. PV Return: allows the control to reestablish the pilot
and de-energize the main flame in response to the sys-
tem heating requirements.
Pilot
Configuration
State Name
Initiate
Initiate
Initiate
Initiate
Initiate
Initiate
Off
—
—
Purge
Control Cool
Low Combustion
Air Only
Pilot Ignition
Main Train
Fuel On
Burner Fuel
Valve Open
(Pilot Timeout)
Release to
Modulation
65-0175
TABLE 5—PILOT CONFIGURATION OPERATING SEQUENCE STATES.
S7800 Keyboard
Display Module
Displayed Text
(See below) The Initiate state allows the relay module to complete initialization
after a power-up or whenever a problem that would prevent normal
operation (such as an ac line problem), the Initiate state is entered.
INITIATE mm:ss Displayed during timed portion of the Initiate state.
INITIATE HOLD: AC Displayed during Initiate state if the ac frequency is low or noise
(AC Freq/Noise) is present.
INITIATE HOLD: AC Displayed during Initiate state if the ac line power was lost.
(AC Line Dropout)
INITIATE HOLD: AC Displayed during Initiate state if the ac frequency is high.
(AC Frequency)
INITIATE HOLD: AC Displayed during Initiate state if the ac line voltage is low.
(Low Line Voltage)
STANDBY Remaining idle until valid input(s) are received. All safety loads are
commanded off.
STANDBY HOLD: F/G Displayed when a flame is detected.
(Flame Detected)
STANDBY HOLD: T7 Displayed when a call for operation is active and the Limits Complete
(Lockout ILK) signal is off.
PURGE HOLD: T18 Displayed when a call for operation is active and the Low Fire Switch
(Low Fire Switch) signal is off.
PURGE 01:00 Purge at high fire. All safety loads are commanded off. Display
indicates Purge type 1 = Purge.
PURGE 02:00 Purge at the motor position commanded by the modulating control.
All safety loads are commanded off. Display indicates Purge type
2 = Control Cool.
PURGE 03:00 Purge at low fire. All safety loads are commanded off. Display
indicates Purge type 3 = Low Combustion Air Only.
PILOT IGN mm:ss Establish a pilot flame. Display shows state and elapsed time. At end
of Pilot Ignition timed state, timer will stop and display will show final
time while a hold exists.
MAIN IGN 00:00 Allow for main valve operators to be placed into the normal operating
condition. Display shows state with zero elapsed time while waiting for
a hold condition(s).
MAIN IGN 00:ss Establish a main flame and drop the pilot flame. Display will show
MFEP state elapsed time.
RUN Allow normal operation to take place where a modulating control
provides the motor position signal.
b. MV Lo Fire: will not allow the pilot to be re-estab-
lished once RUN has been entered; the main valve
remains energized with Lo Fire being the lowest firing
rate allowed.
See Table 5 for the state names, the text that appears on
the S7800 Keyboard Display Module, and the purpose.
Purpose of State
20
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