ADT490 TroubleShooting Introduction to Troubleshooting

ADT490 TroubleShootingIntroduction to

Troubleshooting

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Definition of “Trouble”

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Trouble

a condition in which the fire alarm system

is operating in a degraded mode.

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Trouble

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Why is Troubleshooting so important?

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Troubles/problem that can worsen over time.

Examples: single ground fault turns into a double ground Impact on Signal circuit

power failure

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Why is Troubleshooting so important?

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Central Station/Signal Receiving Operator’s view

minor or complete failure

Investigation of a Problem

urgent for life safety.

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Relevant Codes & Standards

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What code or standard reflects the necessity for troubleshooting?

The Fire Code clearly states

“building owner responsible maintaining fire alarm system functionallity as

“the failure or malfunctioning of the appliance, device or component would adversely affect fire or life safety”.

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Where Can Troubles Occur

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1) Power supply

2) Input circuits

3) Output Circuits

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Where Can Troubles Occur

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4) Device failure

A Beam Detector fully blocked will also cause a trouble signal.

A mis-addressed detector gives Trouble and “Unconfigured device”

5) Intentional (Disable or Bypass).

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What can the customer tell us?

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Owner, superintendent, or custodian.

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Clues

o “ This always happens a couple of days after it rains”.

o “ The phone company was in a while ago or cable guys were working on the 4th floor.”

o “ The pool area has always been a problem

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Ask questions:

o Have there been any contractors working in the building in the past week or two?

what exactly were they doing and

where in the building were they working in?

o When did the trouble condition (or false alarm) occur?

o Have there been any complaints of leaks of any kind?

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Circuit Integrity Review

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Any circuit features the Fire Alarm System needs:

1. Metallic continuity

2. No grounds

3. No wire-to-wire shorts

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Conventional-style Fire Alarm System,

small current through the circuit

the circuit opens and the current stops.

interruption of current detected

displayed as a Trouble condition.

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Addressable-style Fire Alarm System,

digital communication between FACP and devices stops.

lack of response detected by the FACP

displays a trouble condition and

lists the missing device(s)

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Often not obviousdisconnected or break.

Often connection to a device where the open or break occurs.

May be fromimproper stripping - nick

or twisted too tightly under a wire nut (Marrette®).

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Over-tightening screw can result in fracturing

May be some time later.

“opens” may be intermittent - repeated troubles.

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Circuits must be free of grounds - both circuit conductors.

Circuits will tolerate a single ground

still operable

second ground on the other conductor

entire circuit will fail - shorted together

By common ground path ie steel junction box or EMT conduit.

FACP’s detect current increase to ground with a

ground-sensing circuit in the power supply.

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In a conventional panel

a ground condition displayed as “System Trouble”

Recent panels a yellow LED ie “Ground” or “Earth” also lit.

Zone Trouble LED will not be lit – impact on current small

A ground, unlike an open, is not shown as a Zone trouble.

Same for a single ground on signal circuit.

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A wire-to-wire short most dangerous of circuit troubles.

resistance is zero & voltage disappears.

In a signal circuit

a short renders the entire circuit inoperable

In an addressable input / output circuit

short -> all communication STOPS

system “crash”.

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Only on a conventional Initiating circuit (and Sprinkler Supervisory circuit)

short same as manual stations, heat detectors etc

circuit current will increase

FACP sees this as an alarm condition.

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Wire-to-wire shorts are usually from

poor installation practices

stretching wire at conduit bends -> damage insulation

burr cuts through insulation and

provide a short between two conductors

wire-to-wire short same as a double ground condition.

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Faults to Trouble

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1) Open circuit – either on an input circuit or output circuit,

an open -> break in a conductor or

disconnection from a device.

In a conventional system -> loss of supervisory current

FACP and a trouble display (visual and audible) is created.

In addressable system

devices on a Data Communication Link (DCL)

beyond a break reported as missing

with visual and audible Trouble indication.

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Faults to Trouble

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2) Shorted circuit –> unable to support any voltage

Circuit current will increase.

Causes alarm if circuit conventional initiating.

conventional signal -> inoperable.

In an addressable system

DCL communication with the panel STOP.

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Faults to Trouble

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3) Ground – Devices on conventional circuits and addressable DCL circuits

Required to work over a single ground condition.

Double ground same as a short from

to poor installation or water leaking into a device.

`FACP voltage on circuits “floats” above ground

creating a voltage between both “+ve” and “–ve” to earth

allows ground detection on both sides of the circuit.

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How do we know a system is in Trouble?

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1) Audibly – a FACP trouble buzzer

manually silence-able by pressing “Panel Silence”,or “Trouble Silence” etc.

Note:

Buzzer also used with sprinkler supervisory switch

accompanied Supervisory LED

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2) Visually – System Trouble or Common Trouble LED lit.

Look for another LED on.

Typically, only the green “AC On” LED should be lit.

Other LEDs may be hidden behind the front panel.

Some pulsing amber LEDs may be normal (i.e. communication)

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3) Remote from Signal Receiving Centre or

a call from the building owner or property manager.

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What tools will we use in Troubleshooting routines?

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1) Eyes and Ears – Human Detection

Look for flashing LEDs on smoke detectors and Fault Isolators.

Determine if some devices still operate on Trouble.circuit

Carefully note

What indicators are on when you look at the FACP.

Look for messages on the Liquid Crystal Display (LCD).

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2) Logic

What happened immediately prior to the Trouble condition?

What contractors have been in the building?

Recent weather? i.e. rain, likely place for a wet ground?

Identify circuit in trouble with resistor substitution.

Boolean approach divides circuit in half.

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3) Analog or digital multi-meter

read circuit current, voltage, resistance, and

resistance to ground.

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What can the FACP tell us?

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Study the FACP.

Determine if trouble is in one of 5 areasInput,Output,Power,Device trouble,Bypass.

FACP give clue trouble is signal circuit or initiating circuit.

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Exercise - 1

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AC

Battery

SystemAlarmSystemTrouble

Circuit

Ground

SystemSilenced

Bypass

Z1 Alarm

Z1 Trouble

Z2 Alarm

Z2 Trouble

Z3 Alarm

Z3 Trouble

Z4 Alarm

Z4 Trouble

[E] Smoke detector operated on Zone 2, no 115VAC for FACP, wire has broken on Zone 3, signals are operating.

[A] Bells are ringing, a wiring break in Zone 3, Batteries are weak, MPS active in Zone 2

[B] Alarm on Zone 3, open on Zone 2, Emergency lights are on in FACP room

[C] Pull station pulled on Zone 2, power failure, building is quiet, open on Zone 3

[D] FACP breaker has operated, horn is missing, open circuit and single ground on Zone 3

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Exercise - 2

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AC

Battery


Circuit

Ground

SystemSilenced

Bypass

Z1 Alarm

Z1 Trouble

Z2 Alarm

Z2 Trouble

Z3 Alarm

Z3 Trouble

Z4 Alarm

Z4 Trouble

E] Temporal pattern is heard throughout, zones 1-3 are disconnected from the FACP, OS&Y active on Zone 4

[A] Power has been interrupted to the FACP, A pull station is in alarm on Zone 4, An open-circuit trouble on Zone 3, building is quiet.

[B] Double ground has on Zone 4, emergency power is not grounded, signals are operating, main electrical feed to FACP is good.

[C] Building is quiet pull station has been operated on Zone 3 and a double ground has on Zone 4.

[D] Zone 4 bypassed because it is grounded, the building is silent, emergency power is in open circuit trouble, the main power feed is disconnected

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Exercise - 3

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AC

Battery


Circuit

Ground

SystemSilenced

Bypass

Z1 Alarm

Z1 Trouble

Z2 Alarm

Z2 Trouble

Z3 Alarm

Z3 Trouble

Z4 Alarm

Z4 Trouble[E] No choices describe the correct scenario.

[A] All power to FACP has failed, Alarm on Zone 3, Open circuit on Zone 1, building is quiet.

[B] Batteries are charging, signals have failed, Trouble on Zone 1, Alarm on Zone 3

[C] AC is on, battery fuse has failed, heat detector is disconnected on Zone 1, wire disconnected & grounded behind a bell.

[D] Ground on Zone 3, open on battery connection, short on Zone 1, signals are operating.

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Device FailureIn conventional systems,

An internal electrical failure of a device will not cause a Trouble condition, if integrity of the circuit is not affected.

A break in the coil winding of a bell,disconnection of the blocking capacitor in a speaker,corrosion of a switch in a manual station, failure of a photo-receptor in a smoke detector

Device inoperable yet not cause a trouble condition.

Only caught during a regular, periodic inspection.

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Device FailureSome devices can create a trouble signal on their own

these are primarily addressable analog devices

report individual condition like accumulated

dirt or environmental changes.

address not part of the programmed data base will make

generating a Trouble condition, and

displaying a message on the Liquid Crystal Display as

“unconfigured device”.

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Device Failure

Beam Detector

full blockage of the photo - receiver creating a Trouble

warning that it has been rendered inoperable.

Endof

presentation

Documents

ADT490 TroubleShooting Introduction to Troubleshooting