7800 SERIES EC7885A/RM7885A RELAY MODULE
65-0203
9
Dynamic Self-Check Safety Circuit
The microcomputer tests itself and related hardware. If a
microcomputer or related hardware failure occurs and does
not allow proper execution of the self-check routine, safety
shutdown occurs and all safety critical loads are de-
energized.
Expanded Safe-Start Check
The conventional safe-start check, which prevents burner
start-up if flame is indicated at start-up, is expanded to
include a flame signal check during STANDBY and a safety
critical load check.
Off Cycle (Standby) Flame Signal Check
The flame detection subsystem (flame detector and amplifier)
is monitored during STANDBY. If a flame simulating condition
or an actual flame exists, a system hold occurs and start-up is
prevented. If the flame signal exists at any time after the first
40 seconds of STANDBY, a safety shutdown occurs and is
annunciated. A shutter-check amplifier and self-checking
detector are energized for the first 40 seconds during
STANDBY and the last two seconds before exiting STANDBY.
If a flame exists, a safety shutdown occurs. An AMPLI-
CHECK® Amplifier is energized continually through
STANDBY to detect any possibility of a runaway detector or a
flame. If a flame exists, a safety shutdown occurs. A standard
amplifier is energized continually through STANDBY. If a
flame exists, a safety shutdown occurs.
Tamper Resistant Timing and Logic
Safety and logic timings are inaccessible and cannot be
altered or defeated.
First-Out Annunciation and Self-Diagnostics
Sequence Status Lights (LEDs) provide positive visual
indication of the program sequence: POWER, PILOT,
FLAME, MAIN and ALARM. The green POWER LED blinks
every four seconds, signifying that the 7885A hardware is
running correctly.
Optional Multi-Function Keyboard Display Module shows
elapsed time during PILOT IGN. As an additional
troubleshooting aid, it provides diagnostic information and
historical information that is available during normal operation
or when a safety shutdown or hold occurs.
First-out Annunciation reports the cause of a safety shutdown
or identifies the cause of a failure to start or continue the
burner control sequence with text and numbered code via the
optional Keyboard Display Module. It monitors all field input
circuits, including the flame signal amplifier. The system
distinguishes 33 modes of failure and detects and
annunciates difficult-to-find intermittent failures.
Self-Diagnostics add to the first-out annunciation by allowing
the 7885A to distinguish between field (external device) and
internal (system related) problems. Faults associated within
the flame detection subsystem or 7885A are isolated and
reported by the optional Keyboard Display Module. See the
7800 SERIES System Annunciation Diagnostics and
Troubleshooting, form 65-0118.
INSTALLATION
WARNING
FIRE OR EXPLOSION HAZARD CAN CAUSE
PROPERTY DAMAGE, SEVERE INJURY, OR
DEATH
Verification of safety requirements must be performed
each time a control is installed on a burner to prevent
possible hazardous burner operation.
When Installing this Product...
1. Read these instructions carefully. Failure to follow them
could damage the product or cause a hazardous
condition.
2. Check the ratings given in the instructions and on the
product to make sure the product is suitable for your
application.
3. Installer must be a trained, experienced, flame
safeguard service technician.
4. After installation is complete, check out the product
operation as provided in these instructions.
CAUTION
1.
Disconnect the power supply before beginning
installation to prevent electrical shock and
equipment damage. More than one power supply
disconnect may be involved.
2.
Wiring connections for the 7885A are unique;
therefore, refer to Fig. 7 or the applicable
Specification for proper subbase wiring.
3.
Wiring must comply with all applicable codes,
ordinances and regulations.
4.
Wiring, where required, must comply with NEC
Class 1 (Line Voltage) wiring.
5.
Loads connected to the 7885A must not exceed
those listed on the 7885A label or the applicable
Specification, see Table 1.
6.
Limits and interlocks must be rated to carry and
break current to the ignition transformer, pilot
valve, and main fuel valve(s) simultaneously.
7.
All external timers must be listed or component
recognized by authorities who have jurisdiction
for the specific purpose for which they are used.
IMPORTANT
1.
For on-off gas-fired systems, some authorities who
have jurisdiction prohibit the wiring of any limit or
operating contacts in series between the flame
safeguard control and the main fuel valve(s).
2.
Two detectors of the same detection type can be
connected in parallel with the exception of infrared
detectors (C7015).
