Module J8: Security Systems Worksheet Flashcards
What is a security system designed to do?
Protect property and people, and provide a feeling of security
What are the five items that are normally a part of a security system design?
- Deterrence
- Prevention
- Detection
- Response
- Apprehension
What is meant by the “onion-skin” approach?
Successive layers of protection throughout installation
What three purposes does an alarm system serve?
- Deterrence
- Detection
- Response
What are the three categories of protection (layers) using the onion-skin approach?
- Perimeter protection
- Space protection
- Spot protection
What is provided by perimeter protection? What does perimeter protection refer too?
Provides early warning when intruder is still outside. Refers to devices to protect the outer perimeter of an installation
What is space protection designed to do?
Designed to detect the presence of an intruder within a volumetric area
What are the two advantages of space protection over perimeter protection?
Cost effective, less important to anticipate the point of entry
What is the limitation of space protection?
- Does not provide early warning (intruder is already inside the premises)
- Does not allow customer to stay inside protected area
What is spot detection designed to do?
Designed to protect a specific object or area
Where is spot protection usually installed?
Around an item of value (cash, safes, paintings, etc)
What are the three main circuits in a basic alarm system?
- Detection circuit
- Control circuit
- Output circuit
What are the two states of operation for detection circuits?
- Secure (normal)
- Insecure (alarm)
What is the most common output device used with a security alarm system?
Siren
What are the two basic types of detection circuits?
- Closed loop
- Open loop
What detection circuit is the most commonly used?
Closed loop
What circuit provides better protection: a supervised or unsupervised circuit?
Supervised
What are the four basic closed loop types?
- 2-wire
- 2-wire with end-of-line (EOL) resistor
- 4-wire
- 4-wire ULC
Where are two-wire, closed loop circuits used?
Low security applications
Where should the ELR be connected in a two-wire with end of line resistor loop?
At the end of the loop (last device)
Do four-wire loop circuits provide a high or low security for window installations?
High
What advantage does the ULC four-wire loop have over a two-wire loop?
Provides better protection against tampering
Explain the basic operation of magnetic contacts for detection circuits
A magnetic switch is installed in a window or door, when magnet is placed next to it, it changes the state of the contact
What are the four precautions considered when installing reed switches?
- They are fragile
- The have low current rating
- They must be aligned properly
- They must be kept away from metal in vicinity
What is a PIR detector
Passive infrared radiation detector. Detects the presence of heat
What is a passive detector?
It does not radiate any signal
What is the component that is the heart of a passive infrared detector?
Pyroelectric element (PE)
What is a detection pattern?
A pattern of infrared energy monitored by the detection device
What are the five advantages of PIR detectors?
- Self-adjusting
- Foolproof (to install)
- Passive (do not emit radiation)
- Extremely versatile
- Detection fingers are adjustable
What are the three disadvantages of PIR detectors?
- Normal differences in temperature can trip sensor
- Unsupervised detection (can be blocked)
- Range and sensitivity depends on ambient temperature
What are two characteristics of microwave detectors?
- Emit microwave radiation (active device)
- Reacts to doppler shift (change in frequency)
What are two advantages of microwave and ultrasonic detectors over PIR detectors?
- Sense motion toward the detector
- Unaffected be sources of heat
What are three disadvantages of microwave detectors?
- Sensitive to fluorescent and neon lights
- Inability to contain the detection pattern (microwaves pass through walls)
- Water in pipes in the detection range can cause false alarms
What is a Dual-Technology detector?
A type of detector that uses 2 different sensing methods to improve reliability
What is the main advantage of a dual-technology detector?
Reliability and resistance to false alarms
Describe the basic operation of the photoelectric beam detector
Beam of light is emitted from transmitter and directed at the receiver. If an intruder passes through and interrupts the beam, alarm is triggered
What is an advantage of the photo-beam detector?
- Not affected by ambient conditions
- Protects areas too hazardous for PIR
- Good distance
What is a disadvantage of the photo-beam detector?
- Expensive to install
- Takes much longer to setup/adjust
What are the two main types of glass-break detectors?
- Audio detectors
- Shock sensors
What is the principle of operation for an audio detector?
It listens to the sound of breaking glass. If the frequency of the break matches the profile of breaking glass, it triggers alarm
What are the advantages of audio detectors?
Ability to protect large areas
What are four causes of false alarms for audio detectors?
- High-pitched squeaks
- Pet stores (animal noises)
- Metal impact/scraping
- High volume sounds
- Kitchen noises (broken plates, etc)
What are shock sensors? What is the basic principle of operation of a shock sensor?
A unit that can detect a shock wave made by intruder. Piezoelectric crystal acts as a microphone
What is the common number of zones that come with intrusion alarm control panels?
4, 8, 16
What are the three main status LEDs found on the control panel and give a brief description of their function
- Loop status LED
- Ready status LED
- Armed status LED
What are three advanced features found in alarm panels/
- Zone bypass
- System trouble
- Alarm memory
What is a monitoring station?
An offsite location to which alarm panels send communication in the alarm event
What is an “exit delay”?
A feature that gives a user time to exit premises without the system going into alarm
What is a “zone bypass”?
Ability of the security system to bypass (or disable) some of the zones
A four-wire loop is also called a _________ or ________
double circuit, HI/LO loop
In the secure condition on a four-wire loop, there is _______ ________ ________ between the two loops
no current flow
The LO loop is called a ______ loop
24-hour
Where is a four-wire loop system typically found?
In installations using window foil
The contacts on detection devices for four-wire ULC closed loop circuits must be ___________
SPDT, with C, NO and NC terminals
Most reed switches are able to conduct currents of only ______ or less
250mA
