Cleaverbrooks Cb780 User manual

INSTALLATION INSTRUCTIONS

32-00207-01

SIL3

Capable

CB780/CB784

Relay Modules

APPLICATION

The Cleaver-Brooks CB780/CB784 (833-2718/833-

2720) is a microprocessor based integrated burner control

for automatically fired gas, oil, or combination fuel single

burner applications. The CB780 consists of a Relay

Module and Keyboard Display Module. The CB784

consists of the Relay Module only. The Keyboard Display

Module is optional with the CB784. Subbase, Amplifier,

and Purge Card are required to complete the system.

Options include DATA CONTROLBUS MODULE™*, Remote

Display Mounting, First-Out Expanded Annunciator or

Modbus™ Module.

The CB780/CB784 is programmed to provide a level of

safety, functional capability and features beyond the

capacity of conventional controls.

Functions provided by the CB780/CB784 include

automatic burner sequencing, flame supervision, system

status indication, system or self-diagnostics and

troubleshooting

FEATURES

• Safety features:

— Interlock check.

— Closed loop logic test.

— Dynamic AMPLI-CHECK™.

— Dynamic input check.

— Dynamic safety relay test.

— Dynamic self-check logic.

— Expanded safe-start check.

— High Fire Purge Switch test.

— Internal hardware status monitoring.

— Low Fire Start Switch test.

— Tamper resistant timing and logic.

• Access for external electrical voltage checks.

• Application flexibility.

• Communication interface using Modbus Module

833-2820.

• Dependable, long-term operation provided by

microcomputer technology.

• First-out annunciation and system diagnostics

provided by a 2 row by 20 column Vacuum

Fluorescent Display (VFD) located on the Keyboard

Display Module (Optional on CB784).

Contents

Application ..................................................................................... 1

Features .......................................................................................... 2

Specifications ............................................................................... 2

Principal Technical Features .................................................. 6

Safety Provisions ......................................................................... 6

Installation ..................................................................................... 7

Wiring ............................................................................................... 10

Assembly ......................................................................................... 13

Operation ........................................................................................ 17

Static Checkout ............................................................................ 26

Troubleshooting ........................................................................... 26

CB780/CB784 RELAY MODULES

32-00207—01 2

• First-out expanded annunciation with 26 Light

Emitting Diodes (LEDs) for limits and interlocks

(optional).

• Five sequence information Light Emitting Diodes

(LEDs).

• Five function Run/Test Switch.

• Interchangeable plug-in flame amplifiers.

• Local or remote annunciation of operation and fault

information.

• Nonvolatile memory for retaining history files and

sequencing status after loss of power.

• Remote reset (optional).

• Report generation (optional).

• Burner controller data:

— Sequence status.

— Sequence time.

—Holdstatus.

—Lockout/alarmstatus.

— Flame signal strength.

— Expanded annunciator status.

— Total cycles of operation.

— Total hours of operation.

— Fault history of six most recent faults:

• Cycles of operation at time of fault.

• Expanded annunciator data at time of fault.

• Fault message and code.

• Hours of operation at time of fault.

• Sequence status at time of fault.

• Sequence time at time of fault.

— Diagnostic information:

• Device type.

• Flame amplifier type.

• Flame failure response time.

• Manufacturing code.

• On/Off status of all digital inputs and outputs.

• Selected prepurge time.

• Software revision and version of CB780/CB784

and Keyboard Display Module.

• Status of configuration jumpers.

• Status of Run/Test Switch.

SPECIFICATIONS

Electrical Ratings (see Table 1):

Voltage and Frequency: 120 Vac (+10/-15%), 50 or 60 Hz

(±10%).

Keyboard Display Module: 13 Vdc peak full wave rectified

(+20/-15%).

Power Dissipation:

CB780/CB784: 10W maximum.

Display Module: 3W maximum.

Maximum Total Connected Load: 2000 VA.

Fusing: 15A maximum, Type SC or equivalent—fast blow.

CB780/CB784 RELAY MODULES

332-00207—01

aThe CB780/CB784 must have an earth ground providing a connection between the subbase and the control panel or

the equipment. The earth ground wire must be capable of conducting the current to blow the 15A fuse (or breaker) in

event of an internal short circuit. The CB780/CB784 needs a low impedance ground connection to the equipment frame

which, in turn, needs a low impedance connection to earth ground. For a ground path to be low impedance at RF fre-

quencies, the connection must be made by minimum length conductors having maximum surface areas. Wide straps or

brackets are preferred rather than leadwires. Be careful to ensure that mechanically tightened joints along the ground

path, such as pipe or conduit threads or surfaces held together with fasteners, are free of nonconductive coatings and

are protected against mating surface corrosion.

b2000 VA maximum connected load to CB780/CB784 Assembly.

cCan also be 120 Vac, 1A pilot duty, Terminals 8 & 10 sum of the “c“ loads must not exceed 8A.

dCan also be 65 VA pilot duty with motorized valve, 1150 VA inrush, 460 VA open, 250 VA hold.

Environmental Ratings:

Ambient Temperature:

Operating: -40°F to +140°F (-40°C to +40°C).

Storage: -40°F to +150°F (-40°C to +66°C).

Humidity: 85% RH continuous, noncondensing.

Vibration: 0.5G environment.

Dimensions:

Refer to Fig. 1 and 2.

Weight:

CB780/CB784: 1 pound 10 ounces, unpacked.

Keyboard Display Module: 4 ounces, unpacked.

IMPORTANT:

Flame Detection System available for use with

CB780/CB784. To select your Plug-in Flame Sig-

nal Amplifier and matching Flame Detector, see

Table 2.

Table 1. Terminal Ratings.

Terminal No. Description Ratings

GFlame Sensor Grounda—

Earth G Earth Grounda—

L2(N) Line Voltage Common —

3 Alarm 120 Vac, 1A pilot duty.

4 Line Voltage Supply (L1) 120 Vac (+10%/-15%), 50 or 60 Hz (±10%).b

5 Burner Motor 120 Vac, 9.8AFL, 58.ALR (inrush).

6 Burner Controller and Limits 120 Vac, 1 mA.

7 Lockout/Running Interlock 120 Vac, 8A.

8 Pilot Valve/Ignition 120 Vac, 4.5A ignition and 50VA pilot duty.c

9MainFuelValve 120 Vac, 2A pilot duty.d

10 Ignition 120 Vac, 4.5A ignition.c

F(11) Flame Sensor 60 to 220 Vac, current limited.

12 Firing Rate High Fire 120 Vac, 75VA pilot duty.

13 Firing Rate Common 120 Vac, 75VA pilot duty.

14 Firing Rate Low Fire 120 Vac, 75VA pilot duty.

15 Firing Rate Modulate 120 Vac, 75VA pilot duty.

16 Unused —

17 Unused —

18 Low Fire Switch Input 120 Vac, 1 mA.

19 High Fire Switch Input 120 Vac, 1 mA.

20 Preignition Interlock Input 120 Vac, 1 mA.

21 Interrupted/Pilot Valve/First Stage Oil Valve 120 Vac, 2A pilot duty.

22 Shutter 120 Vac, 0.5A.

CB780/CB784 RELAY MODULES

32-00207—01 4

Table 2. Flame Detection Systems (Fig. 3, 4, 5).

aCircuitry tests the flame signal amplifier 12 times a minute during burner operation and shuts down the burner if the

amplifier fails.

bThe 817-1743 Flame Detector should be used only on burners that cycle on-off at least once every twenty-four hours.

Appliances with burners that remain on for twenty-four hours continuously or longer should use the 817-1121 Flame

Detector with the 833-2741 Amplifier as the ultraviolet flame detection system.

cCircuitry tests all electronic components in the flame detection system (amplifier and detector) 12 times a minute

during burner operation and shuts down the burner if the detection system fails. Series 4 amplifiers check 60 to 120

times per minute.

Table 3. Sequence Timing For Normal Operation.a

*STANDBY and RUN can be an infinite time period.

**PURGE will be determined by which purge card is selected.

aThe operating sequence of the CB780 and CB784 Relay Modules are identical. The only difference between the Relay

Modules is that the Keyboard Display Module is standard with the CB780 and optional with the CB784.

bThe MFEP will be determined by which terminal is used, see Fig. 7 and 18.

SIL 3 Capable:

SIL 3 Capable in a properly designed Safety Instrumented

System. See form number 65-0312 for Certificate Agree-

ment.

Approvals:

Underwriters Laboratories Inc. listed, File No. MP268,

Guide No. MCCZ.

Factory Mutual approved, Report No. 1V9A0. AF.

IRI acceptable.

Federal Communications Commission, Part 15,

Class B—Emissions.

Mounting:

833-2725 for panel mount.

Required Components:

CB780: 120 Vac, 50/60 Hz, 833-2718.

CB784: 120 Vac, 50/60 Hz, 833-2720.

Plug-in Flame Signal Amplifier, see Table 2.

Plug-in Purge Timer Cards: selectable:

833-2730—30 sec.

833-2731—60 sec.

833-2732—90 sec.

833-2733—-2-1/2 min.

NOTE: The CB780 and CB784 are identical except for

the Keyboard Display Module which is standard

with the CB780 and optional with the CB784.

Accessories:

Optional:

DATA CONTROLBUS MODULE™—part no. 833-2729.

Provides communication and remote reset capabili-

ties on CB784; remote display capabilities on CB780

and CB784.

CB783 Expanded Annunciator—part no. 833-2726.

Keyboard Display Module—part no. 833-2727. (Stan-

dard on CB780; optional on CB784.)

Remote Mounting Kit for the Keyboard Display, NEMA

4—part no. 833-2740.

Tester—part no. 626-5050.

Plug-In Flame Amplifiers Applicable Flame Detectors

Type Color Self-Checking Part Number

Flame

Failure

Response

Time Fuel Type Part Number

Infrared Red No 833-2722 3 sec. Gas, oil, coal Infrared

(Lead Sulfide)

817-1742

Dynamic

AMPLI-CHECK™ 833-2723a

Red/Whi

No 833-3495 Infrared 817-4133

Dynamic

AMPLI-CHECK™ 833-3496a

Ultraviolet Purple No 833-2724 Gas, oil Ultraviolet 817-1743b

Ultraviolet

Self-Check

Green Dynamic

Self-Check 833-2741cGas, oil, coal Ultraviolet

(Purple Peeper®)

817-1121

Device Initiate Standby Purge

Flame

Establishing

Period

Run

Post

Purge

Timing

Interlock

Circuits

Firing

Rate

Circuit

Energy

Saving

Prepurge

Approval

Code BodiesPilot Main

CB780/

CB784

10 sec. * ** 4 or 10

sec.

10 or

sec.b

* 15 sec. Preignition

, Lockout,

High and

Low Fire

4-wire

modulatin

No FM/IRI

Modulating

CB780/CB784 RELAY MODULES

532-00207—01

Fig. 1. Mounting dimensions of CB780/CB784 Relay Module and 833-2725 Subbase, in inches (mm).

Fig. 2. Mounting dimensions of Keyboard

Display Module, in inches (mm).

Fig. 3. Ultraviolet Self-Check detector, mounting

dimensions in inches (mm).

Fig. 4. Ultraviolet detector, mounting

dimensions in inches (mm).

BURNER CONTROL

POWER

PILOT

FLAME

MAIN

ALARM

RESET

(127)

5 (127)

M23943C

REMOVE ONLY FOR TERMINAL TEST ACCESS.

5-1/4 (133)

BACK

ENTER

Edit: -+

2-1/32

(52)

BURNER CONTROL

29/32

(23)

19/32

(15)

1-1/4

(32)

1-1/32

(26)

5/32

(4)

5/16

(8)

M23388C

1/2

(13)

7/16 (11)

1-5/16

(49) 2-7/16 (62)

29/32

(23)

5/32 (4)

15/32

(12)

3-7/8 (99)

5/16

(8)

13/

(11)

BACK

ENTER

Edit: -+

4-27/32 (123)

4-3/32 (104)

2-3/4

(69)

MOUNTING FLANGE

1/2- 14 NPSM

LEADWIRES FACEPLATE

3/4Ð14 NPT

M20935A

3-3/4

(95)

7-7/32

(183)

5-1/8 (130)

3-7/16

(87)

5-1/4 (133)

817-1121

COLLAR WITH 1/2-14 NPSM

INTERNAL THREADS

4 (102) 6 FOOT (1.83 METER)

LEADWIRES (2)

M20937A

3-1/2 (89)

1-1/16

(27)

817-1743

CB780/CB784 RELAY MODULES

32-00207—01 6

Fig. 5. Infrared detector, mounting dimensions

in inches (mm).

PRINCIPAL TECHNICAL

FEATURES

The CB780/CB784 provides all customary flame

safeguard functions while providing significant

advancements in the areas of safety, annunciation and

system diagnostics.

Safety Shutdown (Lockout) Occurs

If:

1. INITIATE Period

a. Purge card is not installed or removed.

b. Purge card is bad.

c. Configuration jumpers were changed (after 200

hours).

d. AC line power errors, see Operation.

e. Four minute INITIATE period is exceeded.

2. STANDBY Period

a. Flame signal is present after 240 seconds.

b. Preignition Interlock is open an accumulative

time of 30 seconds.

c. Interlock check feature is enabled and the Inter-

lock String (including the airflow switch) is

closed for 120 seconds with controller closed.

d. Ignition/pilot valve/intermittent pilot valve ter-

minal is energized.

e. Main valve terminal is energized.

f. Internal system fault.

g. Purge card is not installed or removed.

h. Purge card is bad.

3. PREPURGE Period

a. Preignition Interlock opens anytime during PRE-

PURGE.

b. Flame signal detected after first ten seconds

during PREPURGE.

c. High Fire Switch fails to close within four min-

utes, fifteen seconds after firing rate motor is

commanded to drive to high fire position at start

of PREPURGE.

d. Low Fire Switch fails to close within four minutes,

fifteen seconds after firing rate motor is com-

manded to drive to low fire position at end of

PREPURGE.

e. Lockout Interlock does not close within 10 sec-

onds.

f. Lockout Interlock opens during PREPURGE.

g. Ignition/pilot valve/intermittent pilot valve ter-

minal is energized.

h. Main valve terminal is energized.

i. Internal system fault.

j. Purge card is removed.

k. Purge card is bad.

4. PILOT FLAME ESTABLISHING Period (PFEP)

a. Low Fire Switch opens.

b. Lockout Interlock opens.

c. Ignition/pilot valve/intermittent pilot valve ter-

minal is not energized.

d. Early Spark Termination terminal is energized

after five seconds.

e. No flame is present at end of PFEP.

f. Internal system fault.

g. Purge card is removed.

h. Purge card is bad.

5. MAIN FLAME ESTABLISHING Period (MFEP)

a. Low Fire Switch opens.

b. Lockout Interlock opens.

c. Ignition/pilot valve/intermittent pilot valve ter-

minal is not energized.

d. Main valve terminal is not energized.

e. No flame is present at end of MFEP.

f. Internal system fault.

g. Purge card is not installed or removed.

h. Purge card is bad.

6. RUN Period

a. No flame is present.

b. Lockout Interlock opens.

c. Main valve terminal is not energized.

d. Internal system fault.

e. Purge card is not installed or removed.

f. Purge card is bad.

7. POSTPURGE Period

a. Preignition Interlock does not close within five

seconds or opens after five-second time period.

b. Ignition/pilot valve/intermittent pilot valve ter-

minal is energized.

c. Main valve terminal is energized.

d. Internal system fault.

e. Purge card is removed.

f. Purge card is bad.

SAFETY PROVISIONS

Internal Hardware Status

Monitoring

The CB780/CB784 checks the purge card for correct

parity to prevent purge timing shifts and circuitry failures.

It also analyzes the integrity of the configuration jumpers

and internal hardware. The POWER LED blinks every four

seconds, signifying an internal hardware check.

Closed Loop Logic Test

The test verifies the integrity of all safety critical loads,

terminals 8, 9, 10 and 21. If the loads are not energized

properly; i.e., the main valve terminal is powered during

PREPURGE, the CB780/CB784 will lockout on safety

shutdown. The CB780/CB784 must react to input

APERTURE

BUSHING WITH

MAGNIFYING LENS COLLAR, 3/4-14 NPSM

INTERNAL THREADS

3/4-14

NPSM

3/4-14 NPSM

INTERNAL

THREADS

HEAT BLOCKCELL MOUNT

M27237A

2 LEADS IN A

48 INCH (1.2 METER)

FLEXIBLE CONDUIT

2-3/4*

(70)

1-1/4

(32)

1-5/8 (41)

1-1/16 (27)

1-1/4

(32)

817-1742 OR 817-4133

817-4133 IS 2-1/4 (58) TOTAL LENGTH

CB780/CB784 RELAY MODULES

732-00207—01

changes but avoid the occurrence of nuisance shutdown

events. Signal conditioning is applied to line voltage

inputs to verify proper operation in the presence of normal

electrical line noise such as transient high voltage spikes

or short periods of line dropout. Signal conditioning is

tolerant of synchronous noise (line noise events that occur

at the same time during each line cycle).

Dynamic Ampli-Check™

Dynamic AMPLI-CHECK™ circuitry tests the flame signal

amplifier during burner operation and shuts down the

CB780/CB784 if the flame amplifier fails.

Dynamic Flame Amplifier and

Shutter Check

Self-checking circuitry tests all electronic components in

the flame detection system and amplifier 10 to 12 times

per minute and shuts down the CB780/CB784 if the

detection system fails.

Dynamic Input Check

All system input circuits are examined to verify that the

CB780/CB784 is capable of recognizing the true status of

external controls, limits and interlocks. If any input fails

this test, a safety shutdown occurs and the fault is

annunciated.

Dynamic Safety Relay Test

Checks the ability of the dynamic safety relay contacts to

open and close. It also verifies that the safety critical loads,

terminals 8, 9, 10 and 21, can be de-energized, as

required, by the Dynamic Self-Check logic.

Dynamic Self-Check Safety Circuit

The microcomputer tests itself and related hardware while

at the same time the safety relay system tests the

microcomputer operation. If a microcomputer or safety

relay failure occurs and does not allow proper execution of

the

self-check routine, safety shutdown will occur and all

safety critical loads will be 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, a

preignition interlock check, an interlock check, and a

safety critical load check.

High Fire Purge and Low Fire Start

Switch Tests

High Fire Purge Switch Test examines the Purge Position

Interlock Switch at the moment the firing rate motor is

commanded to the high fire position. If the switch is

bypassed, welded or otherwise closed prematurely, the

system will automatically add 30 seconds to allow

additional drive time for the firing rate motor to reach or

near the open position before starting the purge timing;

otherwise, purge timing starts when the High Fire Switch

is closed. This switch will also cause a hold (four minutes,

fifteen seconds) condition when the switch is open before

purge or opens during purge. The

CB780/CB784 will lockout and annunciate an alarm if the

switch fails to close within the hold time period.

Low Fire Start Switch Test examines the Low Fire Start

Switch at the moment PREPURGE is completed. If the

switch is bypassed, welded or otherwise prematurely

closed, the system automatically adds 30 seconds to allow

the firing rate motor additional time to reach or near the

low fire start position before ignition trials; otherwise,

ignition trials start after the Low Fire Switch closes. The

test also is used to prove that the firing rate motor is at low

fire position throughout the ignition trial period. This

switch will also cause a hold (four minutes, fifteen

seconds) condition if the switch opens after purging is

complete. The CB780/CB784 will lockout and annunciate

an alarm if the switch fails to close within the hold time

period.

Mandatory Purge

If lockout occurs after the initiation of ignition trials, (or at

anytime during a sequence when the fuel valves may have

been energized), a mandatory POSTPURGE period is

imposed.

Off Cycle (STANDBY or PREPURGE)

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 will occur and be 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 and PREPURGE to detect any

possibility of a runaway detector or a flame. If either

situation happens, a safety shutdown occurs. A standard

amplifier is energized continually through STANDBY and

PREPURGE. If either situation happens, a safety shutdown

occurs.

Preignition Output Circuit Check

At the end of PREPURGE, the Dynamic Safety Relay

operation is checked. Also, all safety critical loads,

terminals 8, 9, 10 and 21 are checked to verify the

terminals are not powered. If the Dynamic Safety Relay

operation is faulty, or if any of the safety critical loads are

powered, safety shutdown occurs and is annunciated.

Tamper-Resistant Timing and Logic

Safety and logic timings are inaccessible and cannot be

altered or defeated.

CB780/CB784 RELAY MODULES

32-00207—01 8

Verified Spark Termination

The ignition terminal is monitored to verify early spark

termination (five seconds ignition and pilot and five

seconds pilot only).

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 to signify the CB780/CB784 hardware

is running correctly.

Multi-function Keyboard Display Module (standard with

CB780, optional with CB784) shows elapsed time during

PREPURGE, PILOT IGN, MAIN IGN, and POSTPURGE. As

an additional troubleshooting aid, it provides sequence

timing, diagnostic information, historical information and

expanded annunciator information when a safety

shutdown or hold or normal operation 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 an English text

and numbered code via the Keyboard Display Module. It

monitors all field input circuits, including the Flame

Signal Amplifier and Firing Rate Position Switches. The

system distinguishes 118 modes of failure and detects

and annunciates difficult-to-find intermittent failures.

Self-Diagnostics adds to the First-out Annunciation by

allowing the CB780/CB784 to distinguish between field

(external device) and internal (system related) problems.

Faults associated within the flame detection subsystem,

CB780/CB784 or plug-in Purge Card, are isolated and

reported by the Keyboard Display Module, see

Troubleshooting section and CB780/CB784 System

Annunciation Diagnostics and Troubleshooting, Bulletin

Number CB-7803.

Interlock Requirements

The following interlock inputs are provided:

Low Fire Interlock

This interlock verifies the firing rate motor is in the low fire

position before and during ignition trials.

High Fire Interlock

This interlock verifies the firing rate motor is in the high

fire position prior to and during PREPURGE.

Lockout Interlock

This interlock (ILK) input signifies a Lockout Interlock. If

the Lockout Interlock is open for more than ten seconds

into PREPURGE, the CB780/CB784 will lockout. After

entering PREPURGE, if the Lockout Interlock opens

during the first ten seconds, the purge timer will be reset.

This provides a continuous PURGE to occur without

interruption before the Pilot Flame Establishing Period. If

a Lockout Interlock opens anytime after ten seconds into

PURGE, during the Ignition Trials or Run, it causes a

lockout.

A typical Lockout Interlock string contains an airflow

switch (see Fig. 7). The Interlock Check is a site

configurable option (see Table 7). If this feature is enabled,

the CB780/CB784 will lockout after 120 seconds

whenever control terminal 6 is energized, and the Lockout

Interlock string (including airflow switch) is closed during

STANDBY.

Preignition Interlock

The Preignition Interlock input is typically connected to

proof-of-closure switches for fuel valve(s). The Preignition

Interlock must be energized throughout PREPURGE. If the

Preignition Interlock opens during STANDBY, it causes a

hold (30 seconds). The CB780/CB784 will lockout if the

interlock does not close within 30 seconds during

STANDBY. If the Preignition Interlock opens during

PREPURGE, it will lockout. If the Preignition Interlock is

open after five seconds into POSTPURGE, the

CB780/CB784 will lockout. The Preignition Interlock is

ignored during the ignition trials state and during RUN.

INSTALLATION

WARNING

Fire or Explosion Hazard.

Can cause severe injury, death or property

damage.

To prevent possible hazardous burner operation,

verification of safety requirements must be

performed each time a control is installed on a

burner.

When Installing This Product…

1. Read these instructions carefully. Failure to follow

them could damage the product or cause a hazard-

ous

condition.

2. Check the ratings given in the instructions and

marked on the product to make sure the product is

suitable for the application.

3. Installer must be a trained, experienced, flame safe-

guard technician.

4. After installation is complete, check out the product

operation as provided in these instructions.

WARNING

Electrical Shock Hazard.

Can cause severe injury, death or property

damage.

Disconnect the power supply before beginning

installation to prevent electrical shock, equipment

and control damage. More than one power supply

disconnect may be involved.

Wiring Information

1. Wiring connections for the CB780/CB784 are

unique; therefore, refer to Figs. 6, 7, 8 or 9 or the cor-

rect Specifications for proper subbase wiring.

2. Wiring must comply with all applicable codes, ordi-

nances and regulations.

CB780/CB784 RELAY MODULES

932-00207—01

3. Wiring, where required, must comply with NEC Class

1 (Line Voltage) wiring.

4. Loads connected to the CB780/CB784 must not

exceed those listed on the CB780/CB784 label or

the Specifications, see Table 1.

5. Limits and interlocks must be rated to simultane-

ously carry and break current to the ignition trans-

former, pilot valve, and main fuel valve(s).

6. All external timers must be listed or component rec-

ognized 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 Flame Detectors can be connected in parallel

with the exception of Infrared Flame Detector

(817-1742).

3. This equipment generates, uses and can radiate

radio frequency energy and, if not installed and

used in accordance with the instructions, may

cause interference to radio communications. It

has been tested and found to comply with the lim-

its for a Class A computing device of Part 15 of

FCC rules which are designed to provide reason-

able protection against such interference when

operated in a commercial environment. Operation

of this equipment in a residential area may cause

interference; in which case, the users at their own

expense may be required to take whatever mea-

sures are required to correct this interference.

4. This digital apparatus does not exceed the Class A

limits for radio noise for digital apparatus set out

in the Radio Interference Regulations of the Cana-

dian Department of Communications.

Humidity

Install the CB780/CB784 where the relative humidity

never reaches the saturation point. The CB780/CB784 is

designed to operate in a maximum 85% RH continuous,

noncondensing, moisture environment. Condensing

moisture may cause a safety shutdown.

Vibration

Do not install the CB780/CB784 where it could be

subjected to vibration in excess of 0.5G continuous

maximum vibration.

Weather

The CB780/CB784 is not designed to be weather tight. If

installed outdoors, the CB780/CB784 must be protected

by an approved weather-tight enclosure.

Mounting Wiring Subbase

NOTE: For installation dimensions, see Fig. 1.

1. Mount the subbase in any position except horizon-

tally with the bifurcated contacts pointing down. The

standard vertical position is recommended. Any

other position decreases the maximum ambient

temperature rating.

2. The 833-2725 Wiring Subbase can be mounted

directly in the control cabinet. Be sure to allow ade-

quate clearance for servicing, installation, access or

removal of the CB780/CB784, Expanded Annuncia-

tor, Keyboard Display Module, flame amplifier, flame

amplifier signal voltage probes, Run/Test Switch,

electrical signal voltage probes and electrical field

connections.

3. For surface mounting, use the back of the subbase

as a template to mark the four screw locations. Drill

the pilot holes.

4. Securely mount the subbase using four no. 6 screws.

WIRING

1. Proper Wiring:

a. For proper subbase wiring, refer to Fig. 7.

b. For proper remote wiring of the Keyboard Display

Module, refer to Fig. 8, 9 or 10 or to the Specifica-

tions for the Keyboard Display Module, Modbus™

Module or DATA CONTROLBUS MODULE™.

2. Disconnect the power supply from the main discon-

nect before beginning installation to prevent electri-

cal shock and equipment damage. More than one

disconnect may be involved.

3. All wiring must comply with all applicable electrical

codes, ordinances and regulations. Wiring, where

required, must comply with NEC, Class 1 (Line Volt-

age) wiring.

4. Recommended wire size and type:

a. All Line Voltage terminals use no. 14 or 16 cop-

per conductor (90°C or higher) 600 volt insula-

tion wire (wire size must be coordinated with fuse

protection). For high temperature installations,

use wire selected for a temperature rating above

the maximum operating temperature. All lead-

wires should be moisture resistant.

b. Keyboard Display Module—For communications

purposes, use an unshielded 22 AWG 2-wire

twisted cable and one wire for ground if the lead-

wire run and noise conditions permit; however,

some installations may need up to five wires,

three for communications and two for remote

reset (in either a single cable or separate cables

for communications or remote reset) or use

Belden 8771 shielded cable or equivalent. The

Keyboard Display Module, DATA CONTROLBUS

MODULE™ (for remote mounting or communica-

tions) or Modbus Module must be wired in a

daisy chain configuration, (1(a)-1(a), 2(b)-2(b),

3(c)-3(c)). The order of interconnection of all the

devices listed above is not important. Be aware

that modules on the closest and farthest end of

the daisy chain configuration string require a

120 ohm (1/4 watt minimum) resistor termina-

tion across terminals 1 and 2 of the electrical

connectors, for connections over 100 feet, see

Fig. 8, 9 and 10.

c. DATA CONTROLBUS MODULE™—For communi-

cations purposes, use an unshielded 22 AWG 2-

wire twisted cable if the leadwire run and noise

CB780/CB784 RELAY MODULES

32-00207—01 10

conditions permit; however, some installations

may need up to five wires, three for communica-

tions and two for remote reset (in either a single

cable or separate cables) or use a Belden 8771

shielded cable or equivalent. The Keyboard Dis-

play Module, DATA CONTROLBUS MODULE™

(for remote mounting or communications) or

Modbus Module must be wired in a daisy chain

configuration, (1(a)-1(a), 2(b)-2(b),

3(c)-3(c)). The order of interconnection of all the

devices listed above is not important. Be aware

that modules on the closest and farthest end of

the daisy chain configuration string require a

120 ohm (1/4 watt minimum) resistor termina-

tion across terminals 1 and 2 of electrical con-

nectors, for connections over 100 feet, see Fig. 8,

9 and 10.

Fig. 6. Internal block diagram of the CB780/CB784 (see Fig. 7, 8, 9, or 10 for detailed wiring instructions.

CONFIGURATION

JUMPERS

MICROCOMPUTER

RESET

PUSHBUTTON

RUN/TEST

SWITCH

STATUS LEDs

PLUG-IN PURGE

TIMER CARD

SAFETY RELAY

CIRCUIT

POWER SUPPLY

KEYBOARD

DISPLAY MODULE

HIGH FIRE

COMMON

MODULATE

LOW FIRE

HIGH FIRE SWITCH

PLUG-IN

FLAME

AMPLIFIER

RELAY

DRIVE

CIRCUIT

CONTROL

POWER

TEST

JACK

REMOTE

RESET

DDL

COMMUNICATIONS

INDICATES FEEDBACK SENSING

TO RELAY STATUS FEEDBACK

AND LINE VOLT INPUTS

FIELD WIRING

INTERNAL WIRING

IGNITION

PILOT

PILOT/V2

MAIN VALVE

RELAY

STATUS

FEEDBACK

AND LINE

VOLTAGE

INPUTS

LIMITS CONTROLLER

LOCKOUT

INTERLOCK

PRE-IGNITION

INTERLOCK

1K1 2K1 5K1

8K1

8K2

9K1

9K2

120 Vac

FLAME SIGNAL

TEST

LOW FIRE SWITCH

PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

DEDICATED DATA LINK.

RS485

(HOT) L2

4K1

7K1

2K2

BLOWER

6K1

ALARM

3K1

M7420A

CB780/CB784 RELAY MODULES

11 32-00207—01

d. Remote Reset—Use no. 22 AWG or greater

twisted pair wire, insulated for low voltage; see

Fig. 8, 9 and 10.

e. Use the recommended wire size for the 13 Vdc

full wave rectified transformer power input of no.

18 AWG wire insulated for voltages and tempera-

tures encountered in the application. Suggested

wire types include TTW(60C), THW(75C) and

THHN(90C).

5. Recommended grounding practices:

a. The earth ground provides for a connection

between the subbase and the control panel of

the equipment. The earth ground wire must be

capable of conducting the current to blow the

20A fuse (or breaker) in event of an internal short

circuit. The CB780/CB784 needs a low imped-

ance ground connection to the equipment frame

which, in turn, needs a low impedance connec-

tion to earth ground. For a ground path to be low

impedance at RF frequencies, the connection

must be made with minimum length conductors

that have a maximum surface area. Wide straps

brackets are preferred rather than leadwires. Be

careful to ensure that mechanically tightened

joints along the ground path, such as pipe or

conduit threads or surfaces held together with

fasteners, are free of nonconductive coatings

and are protected against corrosion on mating

surfaces.

b. Keyboard Display Module, DATA CONTROL BUS

MODULE™ or Modbus™ Module—The shield, if

used, should be connected to the signal ground

terminal 3(c) provided as part of the

CB780/CB784 device ControlBus connection.

Connect the shield at both ends to earth ground.

c. CB780/CB784—Each CB780/CB784 will have

an earth ground terminal that must be grounded

to the metal control panel with wire as short as

practical. Each ground wire must be capable of

carrying a fault current equal to the rating of the

protective fuse (20A). A number 14 copper con-

ductor is adequate, but wide straps or brackets

are preferred rather than leadwires.

6. Recommended wire routing:

a. Flame detector leadwires:

(1) Do not run high voltage ignition transformer

wires in the same conduit with the flame

detection wiring.

(2) Do not route scanner wires in conduit with

line voltage circuits.

(3) Enclose scanner wires without armor cable in

metal cable or conduit.

(4) Follow directions in flame detector Instruc-

tions.

b. DATA CONTROLBUS OR MODBUS MODULE™:

(1) Do not run high voltage ignition transformer

wires in the same conduit or close proximity

with the MODULE™ wiring.

(2) Do not route MODULE™ wires in conduit with

line voltage circuits.

c. Keyboard Display Module (VFD): Because the

VFD is powered from a low voltage, energy lim-

ited source, it can be mounted outside of a con-

trol panel if it is protected from mechanical

damage.

d. Remote Reset:

(1) Do not run high voltage ignition transformer

wires in the same conduit with the Remote

Reset wiring.

(2) Do not route Remote Reset wires in conduit

with line voltage circuits.

NOTE: A 13 Vdc power supply must be used any time

more than one Keyboard Display Module is used.

7. Maximum wire lengths:

a. CB780/CB784 leadwires—The maximum length

of leadwire is 300 feet to terminal inputs (Con-

trol, Preignition Interlock, Running/Lockout

Interlock, High Fire Switch and Low Fire Switch).

b. Flame Detector leadwires—The maximum flame

sensor leadwire length is limited by the flame

signal strength.

c. Remote Reset leadwires—The maximum length

of wire is 1000 feet to a Remote Reset pushbut-

ton.

d. DATA CONTROLBUS or MODBUS MODULE™—

The maximum module cable length depends on

the number of system modules connected, the

noise conditions and the cable used. The maxi-

mum length of all interconnecting wire is 1000

feet.

8. Make sure loads do not exceed the terminal ratings.

Refer to the label on the CB780/CB784 or to the rat-

ings in Specifications; see Table 1.

9. Check the power supply circuit. The voltage and fre-

quency tolerance must match those of the

CB780/CB784. A separate power supply circuit may

be required for the CB780/CB784. Add the required

disconnect means and overload protection.

10. Check all wiring circuits and complete the Static

Checkout, see Table 8, before installing the

CB780/CB784 on the subbase.

11. Install all electrical connectors.

12. Restore power to the panel.

CB780/CB784 RELAY MODULES

32-00207—01 12

Fig. 7. Wiring the CB780/CB784 Relay Module.

M7408A

(L1)

LOCKOUT INTERLOCKS

(INC. AIR FLOW SWITCH)

MASTER

SWITCH

LOW FIRE

START SWITCH

5 SECOND IGNITION

(EARLY SPARK)t

(TERMINATION)

MAIN FUEL

VALVE(S)

BURNER

CONTROLLER/LIMITS

BURNER MOTOR

(BLOWER)

HIGH FIRE

COMMON

LOW FIRE

MODULATE

120V ALARM

10 SEC. INTERRUPTED

PILOT/IGNITION

PREIGNITION

INTERLOCK

SERIES 90

FIRING RATE

MOTOR

SERIES 90

CONTROLLER

817-1742

INFRARED

(LEAD SULFIDE)

FLAME DETECTOR

817-1743

ULTRAVIOLET

FLAME DETECTOR

817-1121

ULTRAVIOLET

FLAME DETECTOR

120V, 50/60 Hz POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

DO NOT WIRE TO ANY UNUSED TERMINALS.

FOR DIRECT SPARK IGNITION (OIL

OR GAS)

IGNITION

TRANSFORMER

FUEL VALVE

(HOT)

L2 1

BLUE

WHITE

YELLOW

WHITE

BLACK

833-2725

15 SEC.

INTERRUPTED

PILOT VALVE

HIGH FIRE

PURGE SWITCH

CB780/CB784 RELAY MODULES

13 32-00207—01

Fig. 8. Wiring multiple Keyboard Display Modules.

(HOT)

C (GND)

+13 VDC

RESET

C (GND)

+13 VDC

RESET

123 45

MOMENTARY

PUSH BUTTON

SWITCH

833-2727 KEYBOARD DISPLAY MODULE

(MOUNTED ON CB 780/CB 784 RELAY MODULE)

13 VDC

POWER SUPPLY

833-2727 REMOTE KEYBOARD DISPLAY MODULE

THREE WIRE SHIELDED CABLE MAY BE REQUIRED. TWO 120

OHM TERMINATING RESISTORS ARE REQUIRED FOR

CONNECTIONS OVER 100 FEET. CABLE SHIELD MUST BE

TERMINATED TO EARTH GROUND AT BOTH ENDS. IF SHIELDED

CABLE IS NOT USED, TWISTED PAIR WIRE MUST BE USED.

M27263A

832-1693

120 OHM

RESISTOR

832-1693

120 OHM

RESISTOR

2TERMINALS OF 833-2760 5-WIRE CONNECTOR (PROVIDED

SEPARATELY).

CB780/CB784 RELAY MODULES

32-00207—01 14

Fig. 9. Wiring the Data ControlBus™ Module with Remote Keyboard Display Module.

ASSEMBLY

Mounting CB780/CB784 Relay

Modules

NOTE: For installation dimensions, see Fig. 1.

Relay Module Mounting

1. Mount the CB780/CB784 vertically, see Fig. 11, or

mount horizontally with the knife blade terminals

pointing downward. The CB780/CB784 must be in

an electrical enclosure.

2. Select the location in the electrical enclosure. Be

sure to allow adequate clearance for servicing,

installation and removal of the CB780/CB784, Key-

board Display Module, flame amplifier, flame ampli-

fier signal voltage probes, electrical signal voltage

probes, and electrical connections.

a. Allow an additional two inches below the

CB780/CB784 for the flame amplifier mounting.

b. Allow an optional three-inch minimum to both

sides of the CB780/CB784 for electrical signal

voltage probes.

3. Make sure no subbase wiring is projecting beyond

the terminal blocks. Tuck wiring in against the back

of the sub-base so it does not interfere with the knife

blade terminals or bifurcated contacts.

IMPORTANT:

The CB780/CB784 must be installed with a plug-

in motion rather than a hinge action.

4. Mount the CB780/CB784 by aligning the four L

shaped corner guides and knife blade terminals with

the bifurcated contacts on the wiring subbase and

tightening the two screws securely without deform-

ing the plastic.

Installing the Purge Card

1. Remove the Keyboard Display Module or DATA

CONTROLBUS MODULE™, see Fig. 13 or 14.

2. Remove the current Purge Card from the

CB780/CB784 by pulling the plastic support cover

upward.

3. Make sure that the Purge Card selected has the

desired timing.

4. Insert Purge Card into the opening of the

CB780/CB784 compartment, see Fig. 12.

832-1693

120 OHM

RESISTOR

832-1693

120 OHM

RESISTOR

C (GND)

+13 VDC

RESET

C (GND)

+13 VDC

RESET

12345

123 45

MOMENTARY

PUSH BUTTON

SWITCH

833-2729 DATA CONTROLBUS OR 833-2820 MODBUS MODULE™

(MOUNTED ON CB 780/CB 784)

833-2727 REMOTE KEYBOARD DISPLAY MODULE

THREE WIRE SHIELDED CABLE MAY BE REQUIRED. TWO

832-1693 120 OHM TERMINATING RESISTORS ARE REQUIRED

FOR CONNECTIONS OVER 100 FEET. CABLE SHIELD MUST BE

TERMINATED TO EARTH GROUND AT BOTH ENDS. IF SHIELDED

CABLE IS NOT USED, TWISTED PAIR WIRE MUST BE USED.

WHEN CONNECTING THE KEYBOARD DISPLAY MODULE DATA

CONTROLBUS MODULE™, OR REMOTE RESET MODULE

EXTERNAL FROM THE CONTROL CABINET, APPROPRIATE

MEASURES MUST BE TAKEN TO MEET EN60730 SAFETY

LOW VOLTAGE REQURIEMENTS (SEE APPROVALS).

M27260A

CB780/CB784 RELAY MODULES

15 32-00207—01

5. Reinstall the Keyboard Display Module or DATA

CONTROLBUS MODULE™ onto the CB780/CB784

and restore power to the device.

6. Run the burner system through at least one com-

plete cycle to verify the system is operating as

desired.

Fig. 10. Electrical panel installation.

IMPORTANT:

The CB780 will not function properly without one

of the following mounted correctly: Keyboard Dis-

play Module, or DATA CONTROLBUS MODULE™.

Mounting Keyboard Display

Module

1. Align the two interlocking ears of the Keyboard Dis-

play Module with the two mating slots on the

CB780/CB784; see Fig. 13.

2. Insert the two interlocking ears into the two mating

slots and with a hinge action push on the lower cor-

ners of the Keyboard Display Module to secure it to

the

CB780/CB784.

3. Verify the Keyboard Display Module is firmly in

place.

Mounting Data ControlBus™

Module

1. Align the two interlocking ears with the two mating

slots on the CB780/CB784; see Fig. 14.

2. Insert the two interlocking ears into the two mating

slots and push on the lower corners of the DATA

CONTROLBUS MODULE™ to secure it to the

CB780/CB784.

3. Be sure the DATA CONTROLBUS MODULE™ is firmly

in place.

Fig. 11. Purge card installation.

Fig. 12. Keyboard Display Module installation.

CB780/CB784 RELAY MODULES

32-00207—01 16

Fig. 13. Data ControlBus™ mounting.

Remote Mounting of Keyboard

Display Module

1. The Keyboard Display Module can be mounted

either on the face of a panel door or on other remote

locations; see Fig. 15.

2. When mounting the Keyboard Display Module on

the face of a door panel, closely follow these instruc-

tions:

a. Select the location on the door panel for flush

mounting. Pay attention to the insertion dimen-

sion of the two Keyboard Display Module screws,

two interlocking ears and the two plug-in con-

nectors to allow for sufficient clearance, 1/4 inch

minimum inward from the surface of the door

panel.

b. Use the Keyboard Display Module as a template;

see Fig. 28. Mark the two screw locations, two

interlocking ear locations and two plug-in con-

nector locations. Drill the pilot holes for the

mounting screws. Provide for two holes on the

door panel for the interlocking ears and plug-in

connector holes.

c. Mount the Keyboard Display Module securing

the two no. 4 screws.

3. A second Keyboard Display Module or a Data

ControlBus™ Module must be installed on the

CB780/CB784. Connections from the module to the

remote display are completed following wiring

shown in Fig.8, 9, 10.

Installing Plug-In Flame Signal

Amplifier

1. Disconnect power supply before beginning installa-

tion to prevent electrical shock and equipment dam-

age. More than one disconnect may be involved.

2. Align the amplifier circuit board edge connector with

the keyed receptacle on the CB780/CB784. Verify

the amplifier nameplate faces away from the Relay

Module, see Fig. 16.

3. Push in the amplifier until the circuit board is fully

inserted into the receptacle and then push the

amplifier toward the CB780/CB784 retaining clasp.

4. Verify the amplifier is firmly in place.

5. Perform all required checkout tests.

Installing the Flame Detector

NOTE: Table 2 lists the flame detection systems avail-

able for use with the CB780/CB784. 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; see Fig. 17.

Keep the flame signal leadwires as short as possible from

the flame detector to the wiring subbase. Capacitance

increases with leadwire 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 9.

Fig. 14. Remote mounting of Keyboard Display Module.

Fig. 15. Flame signal amplifier mounting.

CB780/CB784 RELAY MODULES

17 32-00207—01

Fig. 16. Flame detector wiring.

OPERATION

Sequence of Operation

The CB780/CB784CB780/CB784 has the following

operating sequence, see Fig. 18 and Table 4.

INITIATE

The CB780/CB784 enters the INITIATE sequence when

the Relay Module is powered. The CB780/CB784 can also

enter the INITIATE sequence if the Relay Module verifies

voltage fluctuations of +10/-15% or frequency

fluctuations of ±10% during any part of the operating

sequence. The INITIATE sequence lasts for ten seconds

unless the voltage or frequency tolerances are not met.

When the tolerances are not met, a hold condition will be

initiated and will be displayed on the VFD for at least five

seconds. When the tolerances are met, the INITIATE

sequence will restart. If the condition is not corrected and

the hold condition exists for four minutes, the

CB780/CB784 will lockout. Causes for hold conditions in

the INITIATE sequence:

1. AC line dropout is detected.

2. AC line noise that can prevent a sufficient reading of

the line voltage inputs.

3. Brownouts caused by a low line voltage.

The INITIATE sequence

also delays the burner

motor starter from being

energized and

de-energized from an

intermittent AC line input

or control input.

STANDBY

The CB780/CB784 is

ready

to start an operating

sequence when the

operating control

determines a call for heat

is present. The burner

switch, limits, operating control and all microcomputer

monitored circuits must be in the correct state for the

CB780/CB784 to continue into the PREPURGE sequence.

NORMAL START-UP PREPURGE

The CB780/CB784 provides a PREPURGE timing

selectable from 30 seconds to 2-1/2 minutes with power

applied and the CB780/CB784 operating control

indicating a call for heat:

Running Interlocks, Preignition Interlocks, Burner Switch,

Run/Test Switch, Lockout Interlocks and all

microcomputer

monitored circuits must be in the correct operating state.

1. The blower motor output, terminal 5, is powered to

start the PREPURGE sequence. The firing rate motor

is driven to the high fire position. The PREPURGE

timing does not begin until the Lockout Interlock

String and High Fire Switch are both closed.

2. The Preignition Interlock input must remain closed

throughout PREPURGE; otherwise, safety shutdown

occurs.

BLUE

YELLOW

WHITE

BLACK

M27238A

BLUE

WHITE

INFRARED (817-1742, 817-4133)

ULTRAVIOLET (817-1743)

SOLID STATE SELF-CHECKING

ULTRAVIOLET (817-1121)

1FLAME DETECTOR LEADS ARE COLOR CODED. THE BLUE LEAD MUST BE CONNECTED TO THE F TERMINAL AND THE WHITE

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.

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.

817-1742: 1 BROWN WIRE AND 1 WHITE WIRE FROM THE 817-1742, CONNECT TO THE CB 780/CB 784 WIRING SUBBASE,

COLOR NOT IMPORTANT. 817-4133 1 BLUE WIRE CONNECTED TO THE F TERMINAL AND 1 WHITE WIRE CONNECTED TO

THE GROUND TERMINAL OF THE CB780/784 WIRING SUBBASE. KEEP WIRES AS SHORT AS POSSIBLE AND TWIST THEM.

INITIATE 00:10

Diagnostic Info

M20277A

STANDBY

Total Cycles 132

M20278A

CB780/CB784 RELAY MODULES

32-00207—01 18

3. The Lockout Interlock or Running Interlock inputs

(interlock circuit including Airflow Switch) must

close by ten seconds into PREPURGE; otherwise, a

safety shutdown occurs.

4. After the firing rate motor reaches the PREPURGE

rate position and PREPURGE timing is completed,

the firing rate motor will drive to the low fire position.

5. When the firing rate motor reaches low fire position,

the Low Fire Switch, terminal 18, input must be

energized before entering the Ignition Trial state.

IGNITION TRIALS

Pilot Flame

Establishing

Period (PFEP):

1. With the firing

rate motor at the

low fire position:

a. The pilot valve and the ignition transformer, ter-

minals 8, 10 and 21, are energized. The

CB780/CB784 has a fifteen second interrupted

pilot valve, terminal 21 and a ten second inter-

rupted pilot valve/ignition, terminal 8.

b. During PFEP, the Low Fire Switch must remain

closed. If it opens, a safety shutdown occurs.

c. The Preignition Interlock input is ignored

throughout the Ignition Trial state.

2. Flame must be proven by the end of the four or ten

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,

de-energized for early spark termination.

4. Main Flame Establishing Period (MFEP):

a. The CB780/CB784 has a selectable ten second

or fifteen second MFEP. After the Ignition Trials,

and with the presence of flame, the main fuel

valve, terminal 9, is powered. If a flameout

occurs, the CB780/CB784 will lockout within 3

seconds.

RUN

A ten second

stabilization

period occurs

at the beginning

of the RUN period.

1. The firing rate motor releases to modulation.

2. The CB780/CB784 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.

POSTPURGE

The CB780/CB784

provides a fifteen

second POST-PURGE

following the completion

of the RUN period. The blower motor output is powered to

drive all products of combustion and any unburned fuel

from the combustion chamber. It also supplies

combustion air to burn fuel being purged from the fuel

line downstream of the fuel shutoff valve.

1. The main fuel valve and intermittent pilot valve, ter-

minals 9 and 21, are de-energized and the firing rate

motor is commanded to the low fire position to begin

the POSTPURGE period.

2. The Preignition Interlock closes within the first five

seconds of POSTPURGE.

3. After the fifteen second POSTPURGE period is com-

pleted, the CB780/CB784 reenters STANDBY.

MAIN IGN 00:15

Flame Signal 2.7V

M20284A

RUN

Expanded Annun.

M20285A

POST PURGE 00:12

Device RM7800L

M20286A

PILOT IGN 00:10

Fault History

M20283A

CB780/CB784 RELAY MODULES

19 32-00207—01

Fig. 17. CB780/CB784 sequence.

KEYBOARD DISPLAY MODULE (KDM)

The first line of the Keyboard Display Module provides

current status of the burner sequence (STANDBY, PURGE,

PILOT IGN, MAIN IGN, RUN and POST-PURGE), timing

information (PURGE, PILOT IGN, MAIN IGN and

POSTPURGE) in minutes and seconds, hold information

(PURGE HOLD: T19) and lockout information (Lockout,

Fault Code, Message and Sequence); see Fig. 19. The

extreme right side of the first line will either be blank or it

will show a small arrow pointing to the second line

followed by a two-letter code (DI-Diagnostic Information,

Hn-Fault History Information, and EA-Expanded

Annunciator). When the arrow and two-letter code are

displayed, it indicates the second line is showing a

selectable message submenu. The second line will display

selectable or preemptive messages. A selectable message

supplies information for flame strength, system status

indication, system or self-diagnostics and

troubleshooting. A preemptive message will have

parentheses around the message and supply a detailed

message to support the sequence status information. A

preemptive message can also be a lockout message. A

preemptive message will replace a selectable message to

support the sequence status information. It will also

replace a selectable message after 60 seconds if it or a

lockout message is available. The CB780/CB784 LEDs

provide positive visual indication of the program

sequence: POWER, PILOT, FLAME, MAIN and ALARM.

Fig. 18. Keyboard Display Module and

sequence status LEDs (Table 4).

NOTE: Normal sequences (in Table 4) are in BOLD TYPE,

while abnormal sequences are not in bold type.

CB780/CB784

POWER

VFD

DISPLAY

OPERATING

CONTROLS

AND

INTERLOCKS

BURNER

FLAME

SIGNAL

FIRING

RATE

MOTOR

INITIATE

POWER

STANDBY

POWER

PREPURGE

DRIVE TO

HIGH FIRE

POWER

PILOT

FLAME

MAIN

POWER

PFEP

4 OR 10 SEC

PILOT

FLAME

MAIN

POWER

MFEP

PILOT

FLAME

MAIN

RUN

POWER

POSTPURGE

POWER

STANDBY

00 00 10 25 00 1520

MOTOR OUTPUT SWITCHING

MOTOR ACTION

BURNER/BLOWER MOTOR

IGN.

15 SEC. PILOT

LIMITS AND BURNER CONTROLLER CLOSED

LOCKOUT INTERLOCKS CLOSED

PREIGNITION INTERLOCK CLOSED

LOW FIRE SW.

SAFE START CHECK FLAME PROVING

10 SEC. IGN./PILOT 8

5 SEC.

7TO

20TO

518

13 15

13 12

M7411B

INTERLOCK CHECK

HIGH FIRE SW.

13 14

TO 13 14

MAIN VALVE 9

TIMED

PURGE

POWER

FLAME

MAIN

PILOT

ALARM

POWER

FLAME

MAIN

PILOT

ALARMALARMALARMALARM

PREPURGE

DRIVE TO

LOW FIRE

LED

DISPLAY

PII

SSC

833-2760 FIVE WIRE CONNECTOR FOR

COMMUNICATIONS, REMOTE KEYBOARD

DISPLAY AND REMOTE RESET

SEQUENCE

STATUS

SELECTABLE

MESSAGE OR

PREEMPTIVE

MESSAGE

SEQUENCE

STATUS

LEDs

RESET

PUSHBUTTON

FLAME

SIMULATOR INPUT FLAME CURRENT

TEST JACKS

RUN/TEST SWITCH

DI = DIAGNOSTICS

H1 = HISTORY

EA = EXPANDED

ANNUNCIATOR

CAPTIVE

MOUNTING

SCREW

PLUG-IN

PURGE

CARD

KEYBOARD

DISPLAY

MODULE

RELAY

MODULE

FLAME

AMPLIFIER

M27264B

CB780/CB784 RELAY MODULES

32-00207—01 20

Table 4. Sequence Status Display Information (see Fig. 19).

Burner Sequence LEDs Energized (BOLD type)

INITIATE minutes:seconds

selectable —message