7800 Series RM7824A Relay Module Pages 10-13. CSI 3-Part Specifications.

7800 SERIES RM7824A Relay Module

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Installing Flame Detector

NOTE: Table 2 and Fig. 11 list the flame detectors available for use with the RM7824A. Make sure the correct combination of amplifier and flame detector(s) is used.

Proper flame detector installation is the basis of a safe and reliable flame safeguard installation. Refer to the instructions packed with the flame detector and the equipment manufacturer instructions.

Keep the flame signal leadwires as short as possible from the flame detector to the wiring subbase. Capacitance increases with wire length, reducing the signal strength. The maximum permissible leadwire length depends on the type of flame detector, leadwire and conduit. The ultimate limiting factor in the flame detector leadwire is the flame signal (see Table 6).

1>   FLAME DETECTOR LEADS ARE COLOR CODED. THE BLUE LEAD
MUST BE CONNECTED TO THE F TERMINAL AND THE YELLOW
MUST BE CONNECTED TO THE G TERMINAL. THE UV SENSING
TUBE IS POLARITY SENSITIVE. REVERSING THE LEADS EVEN
MOMENTARILY CAN DAMAGE OR DESTROY THE UV TUBE.

Fig. 11. Flame detector wiring.

OPERATION

Sequence of Operation

The RM7824A has the following operation sequence (see Figs. 12 and 14).

1>  MAIN FUEL VALVE WILL BE ENERGIZED DURING PFEP IF FLAME IS PROVEN.
2>   RM7890A1031 PFEP IS FIXED 30 SECOND.

Fig. 12. RM7824A sequence.

Fig. 13. Sequence status LEDs.

Initiate

The RM7824A enters the INITIATE sequence if the Relay Module verifies voltage fluctuations of outside 22 to 28 Vdc during any part of the operating sequence. The INITIATE sequence lasts for ten seconds unless the voltage tolerance is not met. When the tolerance is not met, a hold condition will be initiated and will be displayed on the optional Keyboard Display Module for at least five seconds. When the tolerance is met, the INITIATE sequence will restart. If the condition is not corrected and the hold condition exists for four minutes, the RM7824A will lock out. Causes for hold conditions in the INITIATE sequence are:

- Vdc dropout is detected.
- Internal timing functions are not synchronized.
- The noise that can prevent a sufficient reading of the low voltage inputs.
- Brownouts caused by low input voltage.

Fig. 14. LED sequence status display information (see Fig. 13).

Standby
The RM7824A is ready to start an operating sequence when the operating control input determines a call for heat is present. The burner switch, limits, operating limit control and all microcomputer monitored circuits must be in the correct state for the RM7824A to continue into the SAFE-START CHECK.

Normal Start-Up Safe-Start Check
The RM7824A verifies that a flame does not exist and proceeds into the ignition trial. If a flame is present, the RM7824A will recycle to the STANDBY period. If the critical loads are not in the correct state, a safety shutdown occurs.

Ignition Trials
Pilot Flame Establishing Period (PFEP):

1. The pilot valve and ignition transformer, terminals 8 and 10, are energized. The RM7824A has an intermittent pilot valve, terminal 8.
2. Flame must be proven by the end of the 4 or 10 second PFEP to allow the sequence to continue. If flame is not proven by the end of PFEP, a safety shutdown occurs.
3. With flame proven, the ignition, terminal 10, is de-energized and the main valve, terminal 9, is energized.

Run
The RM7824A is now in RUN and will remain in RUN until the controller input, terminal 6, opens, indicating that the demand is satisfied or a limit has opened.

Selectable Site-Configurable Jumper
The RM7824A has one site-configurable jumper option, see Fig. 15 and Table 4. The site-configurable jumper should be clipped with side cutters and the resistor removed from the Relay Module.

Fig. 15. Selectable site-configurable jumpers.

IMPORTANT  After 200 hours of operation, the configuration jumper cannot be changed. If it is changed after 200 hours of operation, the RM7824A locks out. The RM7824A cannot be reset and has to be replaced.

SERVICE NOTE: Clipping and removing a site-configurable jumper enhances the level of safety.

STATIC CHECKOUT

!  CAUTION

1. Use extreme care while testing the system. Voltage is present on most terminal connections when power is on.
2. Open the master switch before installing or removing a jumper on the subbase.
3. Before continuing to the next test, be sure to remove the test jumper(s) used in the previous tests.
4. Replace all limits and interlocks not operating properly. Do not bypass limits and interlocks.
5. Close all manual fuel shutoff valve(s) before starting these tests.

Equipment Recommended

1. Voltmeter (20K ohm/volt minimum sensitivity) set on the 0-30 Vdc scale.
2. Two jumper wires: No. 14 wire, insulated, 12 in. (305 mm) long, with insulated alligator clips at both ends.

General Instructions

1. Perform all applicable tests listed in Static Checkout, Table 5, in the order listed.
2. MAKE SURE THAT ALL MANUAL FUEL SHUTOFF VALVE(S) ARE CLOSED.
3. Perform only those tests designated for the specific RM7824A model being tested.
4. Raise the set point of the operating controller to simulate a call for heat.
5. For each test, open the master switch and install the jumper wire(s) between the subbase wiring terminals listed in the Test Jumpers column of Table 5.
6. Close the master switch before observing operation.
7. Read the voltage between the subbase wiring terminals listed in the Voltmeter column of Table 5.
8. If there is no voltage or the operation is abnormal, check the circuits and external devices as described in the last column.
9. Check all wiring for correct connections, tight terminal screws, correct wire, and proper wiring techniques. Replace all damaged or incorrectly sized wires.
10. Replace faulty controllers, limits, interlocks, actuators, valves, transformers, motors and other devices as required.
11. Obtain normal operation for each required test before continuing the checkout.
12. After completing each test, be sure to remove the test jumper(s).

CHECKOUT

! WARNING
Do not allow fuel to accumulate in the combustion chamber. If fuel is allowed to enter the chamber for longer than a few seconds without igniting, an explosive mixture could result. It is recommended that you limit the trial for pilot to ten seconds, and limit the attempt to light the main burner to two seconds from the time the fuel has reached the burner nozzle. In any case, do not exceed the nominal lightoff time specified by the equipment manufacturer. Close the manual shutoff valve(s) if the flame is not burning at the end of the specified time.

! CAUTION
1. Use extreme care while testing the system. Voltage is present on most terminal connections when power is on.
2. Open the master switch before removing or installing the RM7824A.
3. Make sure all manual fuel shutoff valve(s) are closed before starting the initial light-off check and the Pilot Turndown tests.
4. Do not put the system in service until you have satisfactorily completed all applicable tests in this section and any others required by the equipment manufacturer.

! CAUTION
If an RM7824A is replaced with a lower or higher functioning 7800 SERIES Relay Module, the burner will not sequence unless wiring changes are made.

IMPORTANT
1. If the system fails to perform properly, refer to 7800 SERIES System Annunciation Diagnostics and Troubleshooting, form 65-0118.
2. Repeat ALL required Checkout tests after all adjustments are made. ALL tests must be satisfied with the flame detector(s) in its FINAL position.

Equipment Required
Volt-ohmmeter (20K ohm/volt minimum sensitivity):

- 0-6000 ohm capability.
- 0-30 Vdc capability.

Checkout Summary

- Preliminary inspection—all installations.
- Flame signal measurement—all installations.
- Initial lightoff check for proved pilot—all installations using a pilot.
- Initial lightoff check for direct spark ignition of oil—all burners using DSI.
- Pilot turndown test—all installations using a pilot.