Relays used for in Fire Alarm Systems

Relays used for in Fire Alarm Systems 

In an emergency you may wish your fire alarm system to perform a number of automated tasks – this could include grounding a lift or closing doors. To do this you will require fire alarm relays, devices which allow the automation of certain functions.

A relay is a simple electromechanical switch. While we use normal switches to close or open a circuit manually, a relay is also a switch that connects or disconnects two circuits. But instead of a manual operation, a relay uses an electrical signal to control an electromagnet, which in turn connects or disconnects another circuit.

The function of relay module in fire system control is to provide a way for a high-voltage device to be controlled by a low-voltage signal. This is done by closing a switch that activates the device when the fire alarm sends a small current to it. In practice, a relay in a fire alarm system may be used to perform the following functions:

·        Close Doors: A fire alarm relay can be used to automatically shut fire doors in a building when the fire alarm is triggered. This helps to contain the fire and prevent it from spreading.

·        Activate Sprinklers: The fire relay module can be used to activate the sprinkler system in a building when the fire alarm is triggered.

·        Sound Alarms: A fire alarm relay module is often used to activate a sound alarm in an emergency. This warns people in the vicinity of the fire and helps them to evacuate the area.

·        Switch OFF AC Systems: The stream of air coming out of an air conditioner can spread the fire in a building or even smoke and fumes. A fire alarm relay can be used to switch off the AC system and prevent the fire from spreading.

·        Switch On Smoke Exhaust Systems: The smoke exhaust system in a building helps to clear out smoke and fumes. A fire alarm relay can be used to switch it on.

·        Switch Off Loud Music: During a fire, it is important to be able to hear fire alarms and other warnings. a fire alarm relay module is often used to switch off loud music when the fire alarm is triggered so that people can hear the warnings.

Relays can be used to control voltage feeding a particular supply and either apply or drop voltage in the event of a fire activation.

Relays can be used to signal to monitored inputs, these inputs would monitor a nominal EOL resistance and in the event of a fire alarm activation would switch to pick up the trigger value resistance.

Relays can also be used to signal a simple NO/NC contact.

The relay’s load may be AC or DC, but must be within amperage rating of the relay contacts. The relays must be fire alarm listed and supplied by the FACP manufacturer, or be a Listed Fire Relay from a manufacturer.

Off-the-shelf electrical supply relays are not permitted to be directly wired to a fire alarm system. Additionally, polarity must be observed because of the integrated diode used in the relay.

Testing of the fire alarm system includes only verifying the relay changed state, and not necessarily the operational performance of the fire-safety function itself. Proper fire alarm relay operation will be verified by using a meter or by observing an activation LED on the relay.

Question 1: Will your relay be used to supply electrical power or turn it off? You are not responsible for the connection and operation of any other trade’s equipment or function, but you cannot allow the relay to be used improperly. If your relay states it has contacts rated at 10 amps and the owner wishes to turn on 20 amps of outdoor lighting, then they will have to use your relay to switch another device having the proper load rating (i.e. 20 amps or less).

While it is true that the relay, wiring, contactor or equipment could fail without causing a trouble signal on the fire alarm system, you are only responsible for the relay and circuit that you provide up to the switched contacts of the relay. All equipment after your relay contacts is the responsibility of another trade or another contractor.

 

Question 2: Will your relay be used to switch a small current and low voltage signal used by another electrical system, rather than the safety equipment load? Sometimes the load you need to switch amounts to an electrical control signal of just 5V – which another system’s data input needs in order to perform a function. Since you must supply a relay that is used to perform a certain function, you are not responsible for performing everything the owner wants to do. For example, your relay cannot pulse an illuminated street address sign.

 

Question 3: Is the safety function to be performed a code-required fire alarm feature such as controlling elevators, or is it a customer nicety such as opening a driveway gate or turning on outdoor lighting? For a code compliant relay, its wiring must be either fail-safe or cause a Trouble Signal when power to the relay fails.

For Illustrated Relay A

Power to certain emergency safety functions may need to be turned off during an alarm. Examples of these functions commonly include power to electro-magnetic door holders or electro-magnetic door locks. These two examples are normally well within the electrical rating of a fire relay, but a contactor may also be needed if you intend to cut power to a club’s DJ booth, for example, that is providing amplified sound, light and stage effects. If a contactor/relay is also needed, the electrician will supply it.

Relay A rules: Common and Normally Open relay contacts are used to supply a CLOSED circuit to keep safety equipment operational.

This relay’s wiring is “Fail-Safe,” since loss of power to the relay coil will cause the fire-safety function to be performed. No EOL resistor or power supervision relay is required if the emergency function is performed when loss of power to the relay causes the safety function to be performed.

For Relay B

Power to safety functions may need to be turned on during an alarm. This may include smoke exhaust fans and indoor/outdoor lighting. Typically, a 10 amp relay will be used to switch an additional contactor/relay that would be needed for a large rooftop fan, for example.

 

Relay B rules: Common and Normally Open relay contacts are used to supply a CLOSED circuit to deactivate safety equipment upon a polarity reversal signal from the FACP upon alarm conditions.

This relay wiring is NOT “Fail-Safe,” since loss of power to the relay will not cause the fire-safety function to be performed. Instead, this wiring method will cause a FACP trouble signal should there be a fault on the wiring supplying power to the relay.

A circuit fault or any other loss of power to operate the life safety function may need to be supervised. For example, supervision of the electrical power to operate the elevator’s shunt controller is required to ensure the 110vac power to perform the emergency shunt trip is constantly present. The modern self-contained elevator shunt-trip panels contain a set of relay contacts that will close should the shunt-trip lose its operational power for any reason. Wire a dedicated IDC with an EOL resistor across these provided open terminals. Any loss of that 110vac operating power will cause their relay contacts to close and initiate a Supervisory signal. This signal must be specifically and descriptively annunciated (ie “elevator shunt-trip power loss”).

For Relay C

Use only for non-life safety applications or as allowed by the exception (see below).

Relay C rules: Common and Normally Closed and/or Normally Open Relay contacts may be used to activate or to deactivate customer’s equipment. This Relay is NOT “Fail-Safe,” since loss of power to the relay will not cause the fire-safety function to be performed. Also, power wiring to the relay coil can experience a fault without causing a FACP Trouble signal.

An exception allows this relay’s wiring configuration to be used to perform code-required safety functions. This is when a relay output within a control unit is used to activate a function performed by another control unit. This happens when an FACP on-board relay is used to close a set of input contacts of another control panel. For example, you can trip a NAC power booster using the alarm output relay of the main control panel. This exception allows a relay circuit to connect two control units even though the relay wiring is neither monitored for integrity nor provides fail-safe operation.

This wiring exception is only permitted if both control units are located in the same room, the control units are within 20 feet of each other, and the relay wiring connecting both panels is protected against mechanical injury by running it either inside the wall or on the surface using conduit

An elevator company provides a shunt-trip panel whenever the machine room or hoist way includes sprinklers. This panel ensures the elevators will be shut down before sprinkler water can reach sensitive electrical and mechanical components. Your job will be to provide a fail-safe relay (example A) or power-supervised relay (example B), and contacts that will close upon an alarm signal from the hoist way or elevator equipment room detectors.

রিলে কি? 

রিলে একটি সুইচিং ডিভাইস। রিলে এমন একটি সুইচিং ডিভাইস যা সার্কিটে কোন ধরনোর শর্ট সার্কিট সৃষ্টি হলে নিজে ধংস হয়ে সার্কিট কে রক্ষা করে। এই জন্য রিলেকে অতন্দ্রী পহরি বলা হয়ে থাকে।  রিলের মধ্য দিয়ে যদি কারেন্ট প্রবাহিত হয় তাহলে কয়েল মেগনেটাইজ হয়ে কন্টাকের মাধ্যমে সার্কিট কে অন অফ কন্ট্রোল করে থাকে। জরুরি অবস্হায় সার্কিট পুড়ে যাওয়া বা ধংস হয়ে হাত থেকে রক্ষা করে থাকে রিলে। 

রিলে কতো প্রকার কি কি 

ভোল্টেজ অনুযায়ী রিলে দুই প্রকার 

১. এসি রিলে 

২.ডিসি রিলে 

*এসি রিলে আবার ভোল্টেজ উপর ভিত্তি করে অনেক ধরনের হয়ে থাকে

1. 5VAC,6VC,12VAC,24VAC,36VAC, 110VAC,220VAC,440VAC

 কয়েলের ভোল্টেজের উপর ভিত্তি করে এসি রিলে এতো ধরনের হয়ে থাকে।

*ভোল্টেজ উপর ভিত্তি করে ডিসি রিলে বিভিন্ন ধরনের হয়ে থাকে 

1. 5VDC,6VDC,12VDC,24VDC,36VDC, 110VDC,220VDC 440VDC

কয়েলের ভোল্টেজের উপর ভিত্তি করে ডিসি রিলে এতো ধরনের হয়ে থাকে।

রিলে কেন ব্যাবহার করা হয়

১.এসি ভোল্টেজ কে ডিসি রিলে দিয়ে কন্ট্রোল করার জন্য রিলে ব্যাবহার হয়। 

২.সার্কিটে কোন ধরনের ক্রটি বা ক্ষতির সম্মুখীন হলে রিলে হতে জানা যায়। 

৩ রিলে নিজে নষ্ট হয়ে সার্কিট রক্ষা করে।

৪.সার্কিটে কোন ফল্ট হলে রিলে থেকে জানা যায়।

রিলে ব্যাবহারের নিয়ম

প্রতিটি রিলেের গায়ে ডায়াগ্রাম দেওয়া থাকে,  কতো ভোল্টেজ কতো এম্পিয়ার,  কোনটা কোন কন্টাক।

যদি রিলের বডিতে কিছু লিখা না থাকে তাহলে ভিতরে কয়েলের মধ্যে ভোল্টেজ এম্পিয়ার লিখা থাকবে।সেই ভোল্টেজ এবং এম্পিয়ার দেখে কোন জায়গায় ব্যাবহার করা যাবে তা নির্ধারণ করতে হবে। 

রিলে প্রকারভেদ 

সাধারনত তিন প্রকার রিলে হয়ে থাকে 

1.SPST  (Single Pole Single Throw)

2.SPDT (Single Pole Double Throw)

3.DPDT (Double Pole Double Throw

       *SPST রিলে মূলত ৪ পিনের হয়ে থাকে 

       *SPDT রিলে মূলত ৫পিনের হয়ে থাকে 

       *DPDT রিলে মূলত ৮ পিনের হয়ে থাকে

রিলে পিন পরিচিতি 

রিলেতে মূলত তিনটি পিন থাকে 

1.Common 

2.NO 

3.Nc 

1.Common: কমন কয়েলে সার্কিটের সুইচিংয়ের মান অনুযায়ী ভোল্টেজ প্রবাহিত করা হয়। রিলে কয়েলে কোন পজিটিভ নেগেটিভ প্রান্ত নেই তাই এটি পজিটিভ নেগেটিভ যে কোন প্রান্তে সংযোগ করা যায়। রিলের পরিচিত প্রকাশ পায় মূলত তার কয়েল ভোল্টেজ উপর ভিত্তি করে। যে ভোল্টেজে রিলে চালু হয় সেটি রিলের ভোল্টেজ ধরা হয়। 

2.NO: NO এর ফুল মিনিং Normally Open,  অর্থাৎ রিলে যখন নরমাল অথবা কয়েল না ধরা অবস্হায় থাকবে তখন Common এবং NO প্রান্ত বিছিন্ন অবস্হায় থাকবে।  যখন রিলে কয়েল ধরবে তখন অথবা রিলে কয়েল এবনরমাল হবে তখন Common এবং NO প্রান্তটি নিরবিচ্ছিন্ন অবস্হায় কাজ করবে। 

 3.NC: NC এর ফুল মিনিং Normally Close, অর্থাৎ রিলে নরমাল অবস্থা বা কয়েল না ধরা অবস্হায় Common এবং NC প্রান্ত নিরবচ্ছিন্ন অবস্থায় থাকবে বা সংযোগ থাকবে। যখন রিলে কয়েল ধরবে বা রিলে এবনরমাল অবস্হায় থাকবে এখন Common এবং NC বিচ্ছিন্ন অবস্হায় থাকবে। 

রিলে কয়েল পরিচিতি:

রিলে কয়েল ভোল্টেজ অনুযায়ী অনেক ধরনের হয়।  আমরা যে রিলে ব্যাবহার করবো তার কয়েল ভোল্টেজ অনুযায়ী ভোল্টেজ সাপ্লাই দিলে কয়েলটি ধরবে এবং রিলের উপরে থাকা ইন্ডিকেটর লাইটি জ্বলে উঠবে। আবার যখন ভোল্টেজ সাপ্লাই বন্ধ হয়ে যাবে ইন্ডিকেটর টি বন্ধ হয়ে যাবে এবং কয়েলটি বন্ধে হয়ে আগের অবস্হানে চলে আসবে।

Integrating access control and fire systems

Integrating Access Control and Fire Detection Systems 

Most fire jurisdictions require that all doors are automatically unlocked during a fire alarm emergency to ensure a fast exit for those inside the building and a fast entry for the firefighters to do their job. This means the door locking methods (typically electric strikes or electro-magnetic locks)—that are powered and controlled by an Access Control Unit (ACU)—must be kept unlocked during a fire alarm emergency. Fire relay is key product to execute this operation.

What is a fire relay or Output Module?

A output module or control module or fire relay is a switch that sits between the fire system control panel and the power source to the door locking methods. While there are different types of fire relays and different ways to configure them, the job of a fire relay is simple: when there’s a fire alarm, the fire relay unlocks the selected doors.

In an access control system, the fire relay is typically installed inside or near the ACU, and connects the ACU to the fire alarm control panel—as shown in this diagram. Any brand Access Control System can be integrate with Fire, some brand have dedicated port on controller, someone not. You need to verify before getting order. Below arrangement we have test in our experience centre.

Installing a fire relay can be expensive. Follow these tips to get the best pricing.

Lack of a fire relay is one of the most common and expensive surprises we see during customer site surveys. If you’re working with an existing building fire system and it doesn’t already provide a fire relay, you’ll need to get a quote from your building’s fire system provider to install one. 

Unfortunately, the cost of installing a new fire relay can vary significantly. We’ve seen fire relay quotes ranging from Rs. 4000 to Rs. 8000, but there are ways to negotiate for the best pricing. It’s best to include a fire relay as part of your lease agreement with your building management company. If that’s not an option, ask them to negotiate for a fire relay with the building fire system provider on your behalf. Your building management company will likely get better pricing.

If you are building out a new space, you can make a fire relay a part of the general contractor bid so it’s included in the fire alarm system design. Similar to the building management company, your general contractor who is in a position to give repeat business to the fire system provider is more likely to obtain better pricing. Before ordering verify contractor confidence and related document.

Each every manufacture has this module or relay to operate 3rd party equipment Like: Access Control, PA system, Fire Damper, Smoke Damper, AHU etc. If you have Edwards Fire Panel, then only Edwards’s module will be work with proper programming same as Notifier, ESSER, Autronica, GST, Gent any addressable fire brand. If you are not confirm lets contacts us we will guide you free of cost. Last month in this magazine have one article “How to Find a Qualified Fire Alarm Repair Company”, read and safe your property.

As per NFPA the control outputs from a fire alarm control unit can also be sent out on a signaling line circuit (SLC) to an addressable output module, which can open or close a contact based on information sent from the fire alarm control unit on the SLC to the COMM terminals. This is beneficial because multiple output modules can be controlled by the same SLC, which can control each module separately. For example, all output modules controlling all of the door hold opens in a building could be on the same SLC, but based on the specific input to the control unit, only specific doors can be closed. If all of these modules were on the same control circuit, the control unit would only be able to close all the doors.

The Very important clause 21.2.4 of NFPA 72 states that:

NFPA 72, the National Fire Alarm and Signaling Code, clause 21.2.4 addresses the location of emergency control function interface devices.  "Emergency control function interface devices shall be located within 3 ft (0.9m) of the component controlling the emergency control function where the control circuit is not configured as a Class D circuit".

During installation inspections, a frequent comment from inspectors concerns Fire Alarm Control Modules installed too far from the control panel of the equipment they control. As per the above clause, it is true that the modules should be located within 3 ft (0.9 m) of the component controlling the emergency control function. But, there is an exception of not following this rule when used as a Class D circuit. Let us see in which all situations this clause is applicable.

Case A: Physical Proximity

The 3-ft rule is applicable for standard, unmonitored control circuits, which extend from the control module to the control panel of the equipment being controlled. The primary reason for mandating short, unsupervised wire is to minimize the risk of undetected fault and to ensure operational integrity during an emergency. This will be an added benefit during the time of troubleshooting. It should also be noted that the clause uses the term "component controlling the emergency control function" which actually refers to the control relay or terminal strip inside the equipment's control panel (eg: AHU's control panel), not the large mechanical unit itself. The device must be located within 3 ft (0.9 m) of the component that controls the emergency control function. If the device is installed in metal conduit, metal-armored cable, or other equivalently protected enclosures, it can be located up to 20 ft (6.096 m) away.

Context for emergency control functions

Emergency control functions involve the activation of other building systems, such as:

·        HVAC shutdown to prevent the spread of smoke

·        Elevator recall to a designated floor

·        Door releases or closures

Case B: Electronic Surveillance

3-ft rule is not applicable when the control circuit is configured as a Class-D circuit. In this case the cable is directly taken from the Fire Alarm Control Panel and connected to the control panel of the equipment being controlled regardless of how long the cable is, and an End-Of-Line Device (EOLR) will be placed at the end of circuit to complete the supervision loop. As the cable from the Fire Alarm Control Panel is being supervised, the 3-ft rule is not applicable for such cases.

Exception for protective enclosures: If the device is installed in metal conduit, metal-armored cable, or other equivalently protected enclosures, it can be located up to 20 ft (6.096 m) away.

So Class D circuit is a fail-safe pathway for emergency control functions. This means that in the event of a circuit failure, such as a loss of power or a broken wire, the circuit defaults to its intended operational state for an emergency.

The main characteristics of a Class D circuit are: 

·        Fail-safe operation: If there is a failure in the circuit, the controlled device automatically goes into its "fire mode" or safe state.

·        No trouble signal: The fire alarm control panel will not indicate a trouble condition for this type of circuit. This is based on the logic that the failure itself has caused the desired protective action to occur.

·        Annoyance supervision: The system relies on human occupants to notice when the device is not functioning in its normal state (e.g., a door that is normally held open is now closed) and report it for repair.

Common examples

Class D circuits are typically used for control functions that are powered during normal, non-emergency conditions. Examples include: 

·        Door holders: Electromagnets that hold fire doors open are powered by a Class D circuit. In a fire alarm event or power failure, the electromagnet releases, and the door closes.

·        Smoke dampers: A circuit that holds a smoke damper open will de-energize to allow the damper to close upon a fire alarm or circuit failure.

·        Emergency door locks: Fail-safe locks on emergency exits or stairwells are designed to release when power is cut.

·        Fan controls: Fans used for ventilation may be shut down by a fire alarm, and a Class D circuit ensures the fans shut down safely during a power loss. 

Fail-safe consideration: The distance rule can also be waived if the device is configured in a "fail-safe" condition. In this scenario, if the wiring from the relay to the controlled device fails, the controlled device goes into a safe state. A common example is a magnetic door hold-open that releases and closes the door upon power loss, which is the safe condition