Settings And Adjustments; Selectable Site-Configurable Jumpers - Honeywell 7800 Series Installation Instructions Manual

Relay modules

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Product data (64 pages)

Manual (56 pages)

Installation instructions manual (40 pages)

Table Of Contents

Table of Contents

Enlarged version

1. The Airflow Interlock, burner switch, Run/Test switch

and all microcomputer-monitored circuits must also be

in the correct operating state.

2. The motor output, terminal 4, is powered to start the

PREPURGE sequence.

3. The Airflow Interlock input closes ten seconds into

PREPURGE or within the specified purge card timing;

otherwise, a recycle to the beginning of PREPURGE or

lockout occurs, depending on how the Airflow Switch

selectable jumper (JR3) is configured.

Ignition Trials

1. Pilot Flame Establishing Period (PFEP):

a. When the PFEP begins:

(1) The pilot valve and ignition transformer,

terminals 8 and 10 (also terminal 21, RM7897A),

are energized. The RM7897A has an intermittent

pilot valve, terminal 8, and interrupted pilot valve

on terminal 21. The RM7897C has an

interrupted pilot valve, terminal 8.

(2) Flame must be proven by the end of the ten

second PFEP (four seconds if Configuration

Jumper JR1 is clipped) to allow the sequence to

continue. If a flame is not proven by the end of

PFEP, a safety shutdown occurs.

(3) the Pre-Ignition Interlock is ignored throughout

the Trial for Ignition State.

2. Main Flame Establishing Period (MFEP):

a. After PFEP, and with the presence of flame,

the main fuel valve, terminal 9, is powered. If a

flameout occurs, the relay module locks out or

recycles (depending on status of jumper JR2) within

0.8 or 3 seconds, depending on the Flame Failure

Response Time (FFRT) of the amplifier.

b. The RM7897A (terminal 21) and RM7897C

(terminal 8) have a ten second MFEP. After the

Ignition Trials, the interrupted pilot valve, terminal 8

or 21, is de-energized. If a flameout occurs, the

relay module locks out or recycles (depending on

status of jumper JR2) within 0.8 or 3 seconds,

depending on the Flame Failure Response Time

(FFRT) of the amplifier.

Run

1. The RM7897C has a delayed main valve that is

energized once the RUN period is entered.

2. The relay module is now in RUN and remains in RUN

until the controller input, terminal 6, opens, indicating

that the demand is satisfied or a limit has opened.

Post Purge

After demand is satisfied or a limit opens, de-energizing

terminal 6, the Ignition/Pilot valve, main valve and delayed

main valve, terminals 8, 9 and 21, are de-energized. The

blower motor, terminal 4, remains powered during the

specified programmed time. The Pre-Ignition Interlock closes

within the first five seconds of Post Purge.

RM7897A1002, RM7897C1000 7800 SERIES RELAY MODULES

Run/Test Switch

The Run/Test Switch is located on the top side of the relay

module, see Fig. 12. The Run/Test Switch allows the burner

sequence to be altered as follows:

1. In the measured PREPURGE sequence, the Run/Test

Switch, placed in the TEST position, causes the

PREPURGE timing to stop.

2. In the Pilot Flame Establishing Period, the Run/Test

Switch, placed in the TEST position, stops the timer

during the first eight seconds of a ten-second PFEP

selection or during the first three seconds of a

four-second PFEP selection. It also allows for pilot

turn-down test and other burner adjustments. This

activates a fifteen-second flameout timer that permits

pilot flame adjustment without nuisance safety

shutdowns. The Run/Test Switch is ignored during

PFEP for the C relay module if terminals

8 and 9 or 9 and 21 are jumpered.

IMPORTANT

When the relay module is switched to the TEST

mode, it stops and holds at the next Run/Test Switch

point in the operating sequence. Make sure that the

Run/Test Switch is in the RUN position before

leaving the installation.

RUN/TEST SWITCH

SEQUENCE

STATUS

LEDs

RESET

PUSHBUTTON

FLAME

SIMULATOR INPUT

Fig. 14. Sequence Status LEDs.