7800 Series RM7824A Relay Module Pages 18-20. CSI 3-Part Specifications.

7800 SERIES RM7824A Relay Module

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IMPORTANT
1. If the RM7824A fails to shut down on any of these tests, take corrective action (refer to Troubleshooting, RM7824A diagnostics and return to the beginning of all Checkout tests).
2. When all Checkout tests have been completed, reset all switches to original states.

TROUBLESHOOTING

RM7824A System Diagnostics
Troubleshooting control system equipment failures is easier with the RM7824A self-diagnostics and first-out annunciation.  In addition to an isolated spst alarm relay (audible annunciation), the RM7824A provides visual annunciation by displaying the ALARM LED.

Self-diagnostics of the RM7824A enable it to detect and annunciate both external and internal system problems.  External faults such as flame failures and false flame signals are annunciated by a lockout of the RM7824A that energizes the ALARM LEDs by using the optional Keyboard Display Module or 7800 SERIES System Annunciation Diagnostics and Troubleshooting, form 65-0118. 

The RM7824A provides diagnostic information to aid the service mechanic to obtain information when troubleshooting the system; see Table 7 and Table 8.

The optional Keyboard Display Module displays sequence status messages indicating: INITIATE, STANDBY, SAFE-START CHECK, PILOT IGN and RUN. The selectable messages also provide visual indication, current status and historical status of the equipment such as: Flame Signal, Total Cycles, Total Hours, Fault History and Diagnostic Information.

The Expanded Annunciator Terminal Status is not available with the RM7824A. With this information, most problems can be diagnosed without extensive trial and error testing.  Information available in the Diagnostic Information file includes: Device Type, Device Suffix, Software Revision, Manufacturing Code, Flame Amplifier Type, Flame Failure Response Time, Selectable Jumper Configuration Status and Terminal Status.

Diagnostic Information Index
The RM7824A with the optional Keyboard Display Module can monitor input/output terminals and can display the status of the terminal at the VFD (eg, Pilot Valve T9 ON<), see S7800A Keyboard Display Module Specifications. A complete terminal description and terminal number are provided. The display will show the actual status of the terminal. If voltage is detected at the terminal, ON is displayed; but if voltage is not present at the terminal, OFF is displayed.

Historical Information
The RM7824A has nonvolatile memory that allows the Relay Module to retain historical information for the six most recent lockouts. Each of the six lockout files retains the cycle when the fault occurred, the hour of operation when the fault occurred and the fault message and burner status when the fault occurred. The historical information can be viewed by the optional S7800A Keyboard Display Module.

SERVICE NOTE: To check voltages, remove the access slot covers on the sides of the Q7800A,B.

!  CAUTION

Reinstall access slot covers on the Q7800A,B Subbase after performing voltage checks.

Table 7. Sequence And Status Hold Information.

NOTE: Normal sequences are in bold type, while abnormal sequences are in standard type.

Table 7.  Sequence And Status Hold Information

Table 8. Hold And Fault Message Summary.