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MOUNTING FLANGE
7-7/32 (183)
3-3/4
(95)
1/2–14 NPSM
LEADWIRES
FACEPLATE
8
(203)
DIA.
1/2–14 NPT
LEADWIRES
2(51)
9 (229)
Fig. 4. Rectification detectors in in. (mm).
3-3/4 (95)
3-1/4 (82)
C7927A1016
Fig. 5. C7927 detector dimensions in in. (mm).
PRINCIPAL TECHNICAL FEATURES
The RM7824A provides all customary flame safeguard
functions while providing significant advancements in the
areas of safety, annunciation and system diagnostics.
Safety Shutdown (Lockout) Occurs If:
1. INITIATE PERIOD.
a. 24 Vdc power errors occurred, see Operation
section.
b. Configuration jumper has been changed (after 200
hours).
c. Four minute INITIATE period has been exceeded.
2. STANDBY PERIOD.
a. Flame signal is present after 40 seconds.
b. Ignition/intermittent pilot valve terminal is energized.
c. Internal system fault occurred.
d. Main valve terminal is energized.
3. SAFE START CHECK.
3/4–14 NPT
5-1/8
(130)
3-7/16
(87)
5-1/4 (133)
FACEPLATE
C7024E, C7961
1–11-1/2 NPT
PIPE
UNION
1(25)
2-1/16
(52)
2
1-1/2
(51)
(38)
5/16–18 UNC–2B BY
3 (76)
7/16 [11] DEEP
MOUNTING HOLES (2)
C7024F
8 FOOT (2.4 METER)
LEADWIRES (2)
1
(25)
M17783A
a. Flame signal is present.
b. Ignition/intermittent pilot valve terminal is energized.
c. Internal system fault occurred.
d. Main valve terminal is energized.
4. PILOT FLAME ESTABLISHING PERIOD (PFEP).
a. Ignition/intermittent pilot valve terminal is not
energized.
b. Internal system fault occurred.
c. Main valve terminal is energized.
d. No flame present at end of PFEP.
5. RUN PERIOD.
a. Ignition terminal is energized.
b. Internal system fault occurred.
c. Main valve terminal is not energized.
d. No flame present.
e. Pilot valve terminal is not energized.
SAFETY PROVISIONS
Internal Hardware Status Monitoring
The RM7824A analyzes the integrity of the configuration
5
jumper and internal hardware. The POWER LED will blink
(127)
every four seconds, signifying an internal hardware check.
Closed Loop Logic Test
The test verifies the integrity of all safety critical loads,
terminals 8, 9 and 10. If the loads are not energized properly;
M5818
i.e., the main valve terminal is powered during STANDBY, the
RM7824A will lockout on safety shutdown. The RM7824A
must react to input changes but avoid the occurrence of
nuisance shutdown events. Signal conditioning is applied to
24 Vdc voltage inputs to verify proper operation in the
presence of normal electrical line noise such as transient high
voltage spikes or short periods of voltage dropout.
Dynamic Flame Amplifier and Shutter Check
Self-checking circuitry tests all electronic components in the
flame detection system and amplifier twelve times per minute
and shuts down the RM7824A if the detection system fails.
Dynamic Input Check
All system input circuits are examined to assure that the
RM7824A is capable of recognizing the true status of external
controls, limits and interlocks. If any input fails this test, a
safety shutdown occurs and the fault will be annunciated.
Dynamic Safety Relay Test
Checks the ability of the dynamic safety relay contact to open
and close. Verifies that the safety critical loads, terminals 8, 9
and 10, can be de-energized, as required, by the Dynamic
Self-check logic.
Dynamic Self-Check Safety Circuit
The microcomputer tests itself and related hardware, and at
the same time, the safety relay system tests the
microcomputer 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 safety
critical loads will be de-energized.
5
7800 SERIES RM7824A RELAY MODULE
65-0155—2
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