Safety Provisions - Honeywell 7800 Series Manual

RM7823A

SAFETY PROVISIONS

INTERNAL HARDWARE STATUS MONITORING
The RM7823A analyzes the integrity of the internal
hardware. The POWER LED will blink every four seconds,
signifying an internal hardware check.
CLOSED LOOP LOGIC TEST
The RM7823A must react to input changes but avoid the
occurrence of nuisance shutdown events. Signal condition-
ing is applied to line voltage inputs to verify proper opera-
tion in the presence of normal electrical line noise such as
transient high voltage spikes or short periods of line drop-
out. Signal conditioning is tolerant of synchronous noise
(line noise events that occur at the same time during each
line cycle).
DYNAMIC AMPLI-CHECK™
Dynamic AMPLI-CHECK™ circuitry tests the flame
signal amplifier during operation and shuts down the
RM7823A if the flame amplifier fails.
DYNAMIC FLAME AMPLIFIER AND
SHUTTER CHECK
Self-checking circuitry tests all electronic components in
the flame detection system and amplifier 12 times per minute
and shuts down the RM7823A if the detection system fails.
DYNAMIC SELF-CHECK SAFETY CIRCUIT
The microcomputer tests itself and related hardware, and
at the same time, the safety relay system tests the microcom-
puter operation. If a microcomputer or safety relay failure
occurs and does not allow proper execution of the self-check
routine, safety shutdown occurs and all internal relays will
be de-energized.
FLAME SIGNAL CHECK
The flame detection subsystem (flame detector and
amplifier) is monitored at all times when power is applied
to the RM7823A. A shutter-check amplifier and self-check-
ing detector check for a possible runaway detector or
amplifier component failure. If this situation exists, a safety
shutdown occurs. An AMPLI-CHECK™ Amplifier checks
for any possible amplifier component failure. If a failure
exists, a safety shutdown occurs. A standard amplifier is
energized continually.
TAMPER RESISTANT TIMING AND LOGIC
Safety and logic timings are inaccessible and cannot be
altered or defeated.
65-0106—2
Safety Provisions
FIRST-OUT ANNUNCIATION AND
SELF-DIAGNOSTICS
Sequence Status Lights (LEDs) provide positive visual
indication of the RM7823A status: POWER, FLAME, and
ALARM. The green POWER LED blinks every four sec-
onds, signifying that the RM7823A hardware is running
correctly.
Optional Multi-Function Keyboard Display Module flame
signal strength. As an additional troubleshooting aid, it
provides hours of operation, diagnostic information, histori-
cal information and expanded annunciator information when
a safety shutdown or hold or normal operation occurs.
First-out Annunciation reports or identifies the cause of
an alarm with an English text and numbered code via the
optional Keyboard Display Module. It monitors power input
circuits and the flame signal amplifier. The system distin-
guishes 23 modes of failure.
Self-Diagnostics add to the first-out annunciation by
allowing the RM7823A to distinguish internal (system
related) problems. Faults associated within the flame detec-
tion subsystem or RM7823A are isolated and reported by
the optional Keyboard Display Module. See 7800 SERIES
System Annunciation Diagnostics and Troubleshooting,
form 65-0118.
INITIATE
The RM7823A will enter an INITIATE sequence if the
Relay Module verifies voltage fluctuations of +10/-15% or
frequency fluctuations of +/- 10% during the time power is
applied to the device. The RM7823A will hold (five seconds
minimum to four minutes maximum) to allow fluctuations to
stablilize before entering an INITIATE sequence that lasts
for ten seconds. If fluctuations return during INITIATE, the
RM7823A will return to the hold condition and will be
displayed on the optional VFD. If the condition is not
corrected and the hold condition exists for four minutes, the
RM7823A will lockout. Causes for hold conditions in the
INITIATE sequence are:
• AC line dropout is detected.
• Brownouts caused by a low line voltage.
• AC line noise that can prevent a sufficient reading of
the line voltage inputs.
• AC line frequency error caused by using a 60 Hz device
on a 50 Hz line or vice versa.
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