Honeywell 7800 Series Manual page 8

7800 SERIES RELAY MODULES
Table 2. Keyboard Display Module Sequence and Status Hold Messages.
Sequence
The Keyboard Display Module (KDM) indicates the burner status, INITIATE, a stabilization period
INITIATE mm:ss
for the relay module to check for any fluctuations in ac line voltage inputs or control inputs on
power up or during normal operation. The timing of the INITIATE period is either two seconds or
ten seconds, depending on the model, before entering STANDBY.
If the relay module is in an INITIATE HOLD status, the following conditions could exist:
INITIATE HOLD: The KDM indicates the burner status and that it is waiting for excess line noise to clear up, which
(AC Frequency/Noise) prevents sufficient reading of the line voltage inputs. The burner sequence does not advance into
STANDBY until the excess line noise ceases or a line frequency error occurs; this is caused by
using a 60 Hz device on a 50 Hz line, or vice versa on devices with a date code earlier than 9804,
is corrected.
INITIATE HOLD: The KDM indicates the burner status and that ac line power has momentarily dropped out. The
(AC Line Dropout) burner sequence does not advance into STANDBY until the ac line voltage has stabilized
throughout the INITIATE sequence.
INITIATE HOLD: The KDM indicates the burner status and that line frequency is faster than the expected value.
(AC Frequency) The burner sequence does not advance into STANDBY until the line frequency returns to the
proper value; this is perhaps caused by using a 60 Hz device on a 50 Hz line for devices with a
date code earlier than 9804.
INITIATE HOLD: The KDM indicates the burner status and that low line voltage (10% lower than rated voltage) has
(Low Line Voltage) occurred. The burner sequence does not advance into STANDBY until the line voltage is at a
sufficient level for proper operating parameters.
The KDM indicates the burner status, STANDBY. The burner can be placed in STANDBY by
STANDBY
opening the burner switch or if the operating controller indicates its setpoint is satisfied. If a
demand is present for burner operation, the burner sequence does not advance from STANDBY
to PURGE until the recycle limits close. If an Expanded Annunciator is connnected, the display
messages are enhanced.
If the relay module is in a STANDBY HOLD status, the following conditions could exist:
STANDBY HOLD: The KDM indicates the burner status and that a flame is detected. A demand is present for burner
F/G (Flame Detected) operation. The sequence does not advance to PREPURGE until the flame signal clears. If the
flame signal does not clear within 40 seconds, the relay module locks out.
STANDBY HOLD: T20 The KDM indicates the burner status and that the Preignition Interlock is not closed. A demand is
(Preignition Interlock) present for burner operation, but the burner sequence does not advance to PREPURGE until the
Preignition Interlock proves closed. If this time exceeds a 30 second hold, the relay module locks
out.
STANDBY HOLD: T7 The KDM indicates the burner status and that the Lockout Interlock is closed. A demand is
(Lockout Interlock) present for burner operation, but the burner sequence does not advance to PREPURGE until the
Lockout Interlock proves open. If this time exceeds the 120 second hold, the relay module locks
out.
STANDBY HOLD: T7 The KDM indicates the burner status and that the Running Interlock is closed. A demand is
(Running Interlock) present for burner operation, but the burner sequence does not advance to PREPURGE until the
T17 for EC/RM7810, Running Interlock proves open. If this time exceeds the 120 second hold, the relay module locks
7820, 7830, 7850 out.
devices
The KDM indicates the burner status, PURGE, which is the period of time the blower motor is
PURGE
running before the Ignition period. The timing of the PURGE period is selectable.
If the relay module is in a PURGE HOLD status, the following conditions could exist:
PURGE HOLD: T19 The KDM indicates the burner status and that the High Fire Switch is not closed. The firing rate
(High Fire Switch) motor is driving to its PURGE rate position. If this time exceeds four minutes and fifteen seconds,
the relay module locks out.
PURGE DELAY: T19 The KDM indicates the burner status and that the High Fire Switch is jumpered. The High Fire
(High Fire Switch Switch is bypassed, welded or otherwise prematurely closed. The system automatically adds 30
Jumpered) seconds to allow the firing rate motor additional drive time to reach or near the open damper
position before starting the PURGE sequence.
PURGE HOLD: TEST The KDM indicates the burner status and that the Run/Test Switch is in the TEST position. The
(Run/Test Switch) sequence does not continue until the Run/Test Switch is placed in the RUN position.
NOTE: Normal sequences are in bold type, while abnormal sequences are in regular type. This table is for all 7800 SERIES
Relay Modules so all listed steps may not apply to the unit installed.
65-0229—1
Status
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