Security Products

By Paul Rizzuto · April 2008

Information is essential in selecting the appropriate power supplies

It is critical to calculate the power requirements of every system product and consider how they integrate with each other to ensure that the selection and installation of power solutions are appropriate for a project. This information is necessary when selecting the power supplies required to keep the system running efficiently over time. To initiate the selection process, three fundamental areas should be addressed:

Approvals. Are there any specific agency approvals that the installation must meet? Each state, county and even municipality has its own requirements regarding agency approvals. Compliance issues such as UL listings for video, access control and fire/life safety must be adhered to, along with specific local codes.

Features. Before starting the design, a comprehensive analysis of the facility’s security systems is required to determine feature sets of the power supplies. Until recently, selecting power supplies often required combining various components to deliver the functionality desired. All that has changed with the introduction of a new breed of integrated power solutions that delivers both cost and installation advantages.

Devices. How many devices are in the system, and what are the power requirements and physical location of each? This information is a must to determine the size and quantity of the power supplies, how many devices they will run and where they will be located. A good rule of thumb is to add 20 percent more power to your calculations as a safety factor.

Fire Alarm Systems
Power consumption is a primary issue when configuring fire alarm systems. One of the most critical considerations centers on how alarm signals are activated. When an alarm occurs, notification appliance circuits are output from the fire alarm control panel to activate notification appliances, such as strobes and horns. The number of appliances to be activated, along with the current draw for each device and its distance from the FACP, sometimes makes the deployment of NAC power extenders a necessity.

In large commercial installations or multitenant buildings, the total current draw of the notification appliances may exceed the power output of the FACP. In these instances, one or more NAC power extenders needs to be installed for notification appliances with wire runs that are too long for the FACP to deliver sufficient power.

NAC power extenders are available with programmable features that maintain horn and strobe synchronization by producing internally generated sync protocols used by major signal manufacturers or by electronically repeating these sync protocols from the FACP outputs.

Access Control Systems
Access control systems manage ingress and egress at a facility by means of controlled locking devices. NFPA requires that any device or system intended to lock or unlock exits must be connected to the facility’s fire alarm system so all doors will release when an alarm is generated.

To comply with NFPA requirements, there are two classifications of locking devices: fail-safe and fail-secure. Failsafe locking devices, such as magnetic locks, release when they lose power. Failsecure locking devices, such as electric strikes, unlock when power is applied and may be manually released from inside. This determines the manner in which the power solution removes or provides power, as well as the sequence and timing of each action.

Access control power supplies come in AC and DC versions, and some provide multiple voltages simultaneously. Features include independently triggercontrolled fail-safe/fail-secure outputs, power supervision, battery charging and fire alarm interface. Wall- and rackmount models are available.

Some systems also may require the installation of panic hardware devices. Upon activation, the devices’ high-current power demand can reach up to 16 amps, but not all power supplies can handle these high inrush currents. As a result, users need to specify a power supply designed for this type of application. Some operate a single panic hardware device and require optional modules to add features like timing functions or output relays. These base models almost always require extra modules to deliver the necessary func tionality and may not be cost-effective. More advanced models offer integrated features and supply a comprehensive solution.

Video Surveillance Systems
Video surveillance systems typically run all the time, placing high demands on power supplies. These video power supplies need to deliver a clean and consistent source of 24-volt AC or 12-volt DC power for uninterrupted operation.

Depending on the video component’s power requirements and location, a selection of power supplies is available. They can be wall- or rack-mounted, designed for use indoors or outdoors and feature AC or DC outputs. Configurations range from one to 32 outputs, and some models offer additional features.

Other variables to consider when selecting video power supplies include the following:

Environmental conditions. Temperature differences can directly affect the performance of both the video components and the power supply when located outdoors. Enclosures for outdoor power supplies should be rated to withstand the elements.

Ground isolation. In some cases, cameras are not equipped with internal electrical isolation. If this is the case, it’s important to use a power supply with this feature.

Video transmission systems. The introduction of UTP transceiver hubs with integral camera power makes it possible to transmit both video and data via structured cable along with power for the cameras. This is accomplished via video balun/combiners that pass the power and data to the camera and send the video back to the head-end equipment.

An Integrated Solution New devices provide system designers with a highly integrated solution. The unit transmits UTP video, RS422/RS485 data and power over a Cat-5 (or higher) structured cable. Features include eight camera channels in a 1U EIA 19-inch rack-mount chassis, video transmission ranges up to 3,000 feet per channel, and compatibility with AC and DC fixed or PTZ cameras.

An optional HubSat4S Passive UTP Transceiver Hub with integral camera power also can be used to transmit video from up to four cameras over a Cat-5 (or higher) structured cable back to the HubWayLD8S. This new breed of integrated device reduces the time and expense of configuring and installing each component while minimizing bandwidth requirements for large systems.

About the author

Paul Rizzuto
Paul Rizzuto is the technical sales manager at Altronix Corp.