5 Power Supply Myths You Need to Unlearn

Power supplies have progressed rapidly with technological innovation. Here are the facts about linear power to battery charger performance and more.
Published: August 6, 2015

Forget any pre-disclosed notions you have about power supplies. These devices have progressed rapidly with technological innovation, far from the static hardware category they were relegated to in the past. They are smart, networked, intelligent solutions that yield remote service and monitoring and assist the end user in delivering consistent uptime and 24/7 reliability.

Here are five myths we are ‘busting’ so systems integrators can better understand the technology behind these devices.

Myth 1: Use only linear power supplies for clean output.

Facts: Linear power supplies are an older technology and are inherently inefficient. A large, step-down transformer is required and the regulator operates by “burning off” extra voltage as heat. Efficiency levels for linear power supplies are typically in the 65 percent range and are generally limited to a single, pre-configured output voltage dependent on the input transformer. Linear power supplies are generally being phased out, driven by state and federal regulations.

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Today’s offline switching supplies (OLS) are capable of operating with a cleaner power output than linear. Less noise and ripple is generated as opposed to linear, especially during high-power operation. An OLS power supply operates on the same principles as a switch mode power supply, but eliminates the need for a step-down transformer, improving efficiency, while reducing weight and heat output.

In fact, heat generation is much greater in linear power supplies. An OLS power supply is able to achieve nearly 90 percent efficiency and far lower operating temperatures than either a linear or switch mode power supply.

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In addition, the efficiency ratings of linear supplies are no longer acceptable at the Federal level, as well as in some states, such as California and Maine. Finally, it may be difficult or impossible to specify linear solutions from a design standpoint to meet the Sixth Edition of Underwriters Laboratories 294 (UL 294) Standard for Access Control System Units.

Myth 2: Power supplies are a commodity product, so it’s best to use the cheapest device available to save money.

Facts: Power supplies are far from a commodity item. They offer enhanced features to eliminate having to purchase necessary features separately. The power supply has evolved from a simple device to a total power supply system, offering single and dual voltage, power distribution, lock and output control, remote test capability, remote diagnostics and remote reporting capabilities.

Myth 3: A power supply is not really integral to the system and therefore has no value added.

Facts: The power supply is a critical part of the operability of any security or life safety system. It’s responsible for ensuring that the entire solution receives the power needed to operate correctly. Today’s power supplies are manufactured with the end user in mind, and these devices reduce design time by including necessary features in base products.

Myth 4: Power supplies cannot make additional improvements from their current status.

Facts: The efficiency, feature sets and available diagnostics will continue to improve over the next generation of products. Devices will continue to integrate – with the ability of hardware and software to communicate more wholly through protocols such as physical logical access interoperability (PLAI) profile and simple network management protocol (SNMP) – as well as foster easier use and user transparency.

Myth 5: The battery charger performance of power system solutions is all the same.

Facts: Chargers are not created equal . The design will add or subtract greatly to battery life, directly affecting the number of service calls, battery replacement time and the maximum amp-hour size of battery which can be used. Most of the current charger designs deployed use the positive temperature coefficient (PTC) approach, with the charging voltage coming from the main supply output, an older design that had merit years ago but no longer today.

In order to properly charge a battery with the requirements of the new Sixth Edition UL 294 ratings, the best approach is a separate charging circuit and control mechanism, which is available in the more intelligent power supplies on the market today.

Joe Holland is a co-founder and the vice president of Engineering for LifeSafety Power Inc., based in Mundelein, Ill. He has decades of experience in the security alarm and power industries.

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Tagged with: Backup Power

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