Honeywell RM7890A,B,C 7800 Series Troubleshooting Manual

Also See for 7800 Series:

Product data (64 pages)

Manual (56 pages)

Installation instructions manual (40 pages)

Table of Contents

Contents

1 Troubleshooting
2 Documents / Resources
- 2.1 Download manual

Honeywell RM7890A,B,C 7800 Series Troubleshooting Manual

Troubleshooting

RM7890 SYSTEM DIAGNOSTICS
Troubleshooting control system equipment failures is easier with the RM7890 self-diagnostics and first-out annunciation. In addition to an isolated spst alarm relay (audible annunciation), the RM7890 provides visual annunciation by displaying the ALARM LED.
Self-diagnostics of the RM7890 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 RM7890 that energizes the ALARM LED by using the optional Keyboard Display Module or 7800 SERIES System Annunciation Diagnostics and Troubleshooting, form 65-0118.
The RM7890 provides diagnostic information to aid the service mechanic to obtain information when troubleshooting the system, see Table 6.
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, Diagnostic Information and Expanded Annunciator Terminal Status (if used). 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 RM7890 with the optional Keyboard Display Module can monitor input/output terminals and can display the status of the terminal at the VFD (e.g. Pilot Valve T8 ON<), see S7800A1001 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 Index
The RM7890 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 S7800A1001 Keyboard Display Module.

SERVICE NOTE: A restart of an RM7890 can be accomplished by pressing the reset pushbutton on the RM7890, or by pressing a remote reset pushbutton wired through an optional Keyboard Display Module, DATA CONTROLBUS MODULE, Extension Cable Assembly, or Remote Reset Module. A power-up reset will cause an electrical reset of the RM7890 but will not reset a lockout condition.

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

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

SERVICE NOTE: Maximum ambient operating temperature of a C7012E,F Series 1 through 6 will be reduced to 125°F because of the duty cycle operation of the RM7890B Relay Module.

TABLE 6—SEQUENCE AND STATUS HOLD INFORMATION.
NOTE: Normal sequences are in bold type, while abnormal sequences are not in bold type.

Sequence	Information
INITIATE	The LED indicates the burner status, POWER, which is a stabilization period for the RM7890 to check for any fluctuations in AC line voltage inputs or control input on power-up or during normal operation. The timing of the INITIATE period is ten seconds before entering STANDBY.
If the RM7890 is in a HOLD status, the following conditions could exist:
INITIATE HOLD: (AC Frequency/Noise)	The LED indicates the burner status, POWER, and that the RM7890 is waiting for excess line noise to clear up. The burner sequence will not advance into STANDBY until the excess line noise, which prevents sufficient reading of the line voltage inputs, ceases or a line frequency error is corrected (perhaps caused by using a 60 Hz device on a 50 Hz line, or vice versa).
INITIATE HOLD: (AC Line Dropout)	The LED indicates the burner status, POWER, and that AC line power has momentarily dropped out. The burner sequence will not advance into STANDBY until the AC Line voltage has stabilized throughout the INITIATE sequence.
INITIATE HOLD: (AC Frequency)	The LED indicates the burner status, POWER, and that line frequency is faster than the expected value. The burner sequence will not advance into STANDBY until the line frequency returns to the proper value (perhaps caused by using a 50 Hz device on a 60 Hz line).
INITIATE HOLD: (Low Line Voltage)	The LED indicates the burner status, POWER, and that low line voltage has occurred. The burner sequence will not advance into STANDBY until the line voltage is at a sufficient level for proper operating parameters.
STANDBY	The LED indicates the burner status, POWER. The burner can be placed in STANDBY by opening the burner switch or if the operating controller indicates its set point has been satisfied. If a demand is present for burner operation, the burner sequence will not advance from STANDBY to SAFE START CHECK until the recycle limits close.
If the RM7890 is in a HOLD status, the following conditions could exist:
STANDBY HOLD: F/G (Flame Detected)	The LEDs indicate the burner status, POWER and FLAME, and that a flame is detected. A demand is present for burner operation. The burner sequence will not advance to SAFE START CHECK because a flame is detected as being present. The sequence will not advance to SAFE START CHECK until the flame signal clears. If the flame signal does not clear within 40 seconds, the RM7890 will lockout.
SAFE START CHECK	The LED indicates the burner status, POWER, which is the period of time after STANDBY. The RM7890 is verifying that a flame is not present before the start of Ignition Trials. If a flame is present, the RM7890 will recycle to STANDBY.
PILOT IGN	The LEDs indicate the burner status, POWER, PILOT and FLAME, which is the period of time the RM7890 permits the pilot valve and ignition to be energized and the pilot flame to be established.
RUN	The LEDs indicate the burner status, POWER, PILOT, FLAME and MAIN, which is the period of time after the Ignition Trials and before the operating controller set point is reached. During this time, the burner is firing under the control of the operating controller.
RESET/ALARM TEST	The LED indicates the burner status, POWER and ALARM. This condition indicates that the reset pushbutton is pressed. If it is held for more than four seconds, the alarm output is energized. The alarm output will be de-energized after the reset pushbutton is released.