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Emergency Systems

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Batteries and Storage Batteries

The very basic necessity of emergency systems is power. Whether or not we get that from batteries or a generator is primarily reliant on how long we have to supply the source. If there is a large supply needed for a long period, it only makes sense to install a generator. If the need is only a few lights for momentary egress (exit), than an installation of battery backup would be sufficient. In the following topic we will discuss batteries, UPS systems and generators.



Cells

Is a basic unit that converts chemical energy into electrical energy.



Battery


A battery is usually composed of two or more cells which can be series/and or parallel connected.
Please look below to voltage and amp hours.
Primary Cells - One time use. (Dry Cell)
Secondary - Rechargeable, storage batteries


Two Types of Batteries

Primary Cells - One time use. (Dry Cell)
Secondary - Rechargeable, storage batteries


Battery Ratings

Voltage - is the nominal 'open circuit' voltage (OCV)
Capacity - (C) is measured by (Ahr) ampere hours


Primary - Dry Cell - One Time Use

Carbon Zinc (Leclanche) - room temperature batteries/ toys / flashlights
Zinc Chloride - 50% more power than carbon zinc.
Alkaline - manganese / has an anode (+) and a cathode (-)
Mercury - button type / seen in hearing aids
Silver Oxide - costly / almost flat discharge / miniature
Lithium Cells - long shelf life, 3V (highest voltage) strobes, etc


Secondary Batteries - Rechargeable - Long Life Storage Batteries

Lead Acid- 'open circuit' potential, maintenance free
Nickel Iron- Also Known As (AKA) Edison
Nickel Cadmium
Lithium Ion

Voltage and Amp Hours

When you have a battery bank that is used for emergency (back up) power, there is usually a set procedure on how to connect the batteries. Depending on the usage and the duration, is how you set up the banks in parallel/series/or both.


So if you are setting up for series or parallel, here is a quick view of the amp hour calculations you'd see for each set up.




Charges

Initial charge- after it's filled with electrolyte
Normal- routine charge to fully charged
Trickle- compensate for self discharge
Emergency-charges at a high current rate
Float Charge- the battery and the load are connected in parallel. Like a car.


Battery Safety

Batteries present unique hazards and must be handled according to procedures. The presence of acids in wet cell batteries, and the release of gases when charging, can create unique environments that require safety planning before starting work. ALWAYS consult the owner's manual or the recommended safe work practices for your firm before working with batteries.




Generators

Generator Sets - are generator driven by a prime mover which can be powered by gasoline, diesel, propane, natural gas, or butane. A governor regulates output.



NBC - National Building Code of Canada

The NBC requires that in the event of power failure, the emergency equipment will provide power for a specified amount of time. These sources can be batteries, motor generator sets, uninterruptible power supply (UPS) or a separate service.



Automatic Transfer Switch

Engine driven 8-15 seconds to come online
(mechanically and electrically interlocked)

* Voltage and frequency must match utility supply. Voltage regulation is used.

* Paralleling gen sets requires extra control equipment to synchronize.



An automatic transfer switch senses when power has changed in order to automatically transfer power in an emergency.


UPS - Uninterruptible Power Supply

Is a temporary power source for vital loads consisting of a converter, and inverter, and control equipment for a minimal amount of time.

Offline UPS (4 milliseconds interruption)
Online UPS (No interruption)



These types of systems use maintenance free lead acid storage batteries. They provide backup power and surge suppression that help minimize electrical noise.

Ferro Resonant Type - exhibits characteristics of an online UPS. It has a three winding transformer which provides limited regulation.

Most UPS are rated in (VA) volt-amperes or kilo-volt-amperes (kVA) They should be sized for the amount of power that is essential. They can also act as a seamless integration to transfer power to a generator for a longer operation.

You can also have a portable UPS for computer loads.




Fibre- Optic

You ask yourself what does fibre - optic have to do with emergency systems? Without the use of fibre-optics we would be unable to communicate on several levels during a blackout. These cables are placed in our communication infrastructure in cities and rural areas. Fibre optic systems transmit data from one place to another using light. There are four main components:
1) the transmitter (electrical to light)
2) optic cable (fibre)
3) optical connectors
4) the receiver (light to electrical)



Section 56 of the CEC
1) Non Conductive (no metal or electrical conductive)
2) Conductive ( metal strength, metal shields, metal vapour barrier)
3) Hybrid Cables (both fibre cables and current carrying conductors - twisted pair)

The light used in most fibre optic systems is Infrared. A particle of this light is called a photon. As the frequency increases it`s waveform decreases.



The amount of attenuation (loss) can be kept to a minimum by installing a proper splice.

*Cable preparation is strongly advised by manufacturer`s preparation guides and specifications. This normally requires an additional class to train personnel.




Emergency Lighting

Is a system, that when well maintained, can aid in an emergency situation. Several different bodies govern the specifications and codes in this area. NBC, CEC, CSA, and provincial codes. (See below)

There are three different devices used in emergency lighting. Emergency Units (Packs), Exit lights, and remote heads.

The Emergency Unit is mainly made of a rechargeable battery, trickle charger, voltage indicating light, test switch, and a transfer relay. The battery can be 6, 12, or 24 volt (lead acid). The bulbs can be tungsten halogen.

The exit lights do not have a battery like an Emergency Unit. Many new lights are manufactured with LED`s and are quickly cornering the market because of new Canadian energy conservation laws. They have a longer life than a conventional bulb, and are more efficient.

Code Highlights

CEC Section 46
- Minimum mounting height to the bottom of emergency unit (2.0m)
- Height of receptacles feeding emergency unit (at least 2.5m from the floor, and no more than 1.5 away from unit)

NBC
- Must provide illumination for no less than 30 minutes
- Corridor, stairwells to have no less than 50 lux
- Average levels no less than 10 lux

CSA
- Must be tested once a month
-Voltage must remain above 91 % during entire test
- A permanent record must be kept for maintenance and inspections.