Tech Tips: Power Supplies

The power supply is a critical element in electronic access control (EAC) and video surveillance systems. A faulty power supply can lead to all sorts of problems, including image-quality issues for video surveillance systems, malfunctioning locks, or intermittent operation of accessories or controllers. Of course, the system could shut down if the power supply were to fail.

Power Supply Types

Before discussing how to avoid these problems, it’s important to know the types of power supplies you might work on. These are the following:

Linear: These are the traditional power supply and use transformers. They work well with everything.

Switching: These power supplies don’t use transformers and are lighter and more compact. However, they have a reputation for generating “noise” on the line, which might crash some delicate processors.

PoE: A Power over Ethernet (PoE) power supply uses network cabling to distribute the power and is used extensively for video surveillance systems. I switched from coax cable to CAT5 (now CAT6) and PoE many years ago. A lot of installed video surveillance systems still use coax and non-PoE power supplies. Repairing these systems pays well.

Solar: These power supplies are used with backup batteries and engineered to provide uninterrupted power to homes and appliances, such as gate operators, located where hard-wiring isn’t practical or possible.

Self-regenerative:  Although not strictly a power supply, per se, some security equipment, such as door operators, generates its own power to operate.

Battery:  Batteries, of course, are used on many stand-alone EAC devices and on video surveillance cameras. Batteries work great on EAC devices, but I’m not a fan of video surveillance cameras that use batteries. When rechargeable batteries are paired with solar panels to recharge them and the battery capacity of the camera power supply tolerates the duty cycle, it will work until there is no sun for a day or two. Keep that in mind if you live in rainy areas.

Hybrid: A hybrid power supply uses multiple technologies to achieve enhanced performance.

UPS: An uninterruptible power supply (UPS), also known as a battery backup, provides backup line voltage power under normal conditions and when the power utility fails or when line voltage drops to an unacceptable level. It also filters transients, or power surges, that exceed a device’s allowable parameters. The size and design of a UPS determine how long it will supply power.

In the Field

When it comes to installing a power supply, there are a few differences when doing a retrofit compared with doing a new installation. Regardless of which, I recommend that you use a dedicated line voltage circuit from the breaker panel of sufficient amperage to power the necessary equipment and don’t exceed the maximum load of the power supply. Also, use a UPS whenever possible.

For retrofits:

Calculate, measure or estimate voltage drops to determine whether the wire is of adequate gauge and the proper type to meet code. Also, make sure the cabling is installed properly. Note how it’s attached above the ceiling, so it stays in place, or how it’s protected beneath the ceiling, so it won’t be affected by normal activity.

For new installations:

The same techniques for retrofits otherwise apply to new installations, but also make sure to use power distribution modules as necessary to isolate each device and prevent catastrophic system failure.

When you install a power supply, you should do the following:

• Locate it in a secure area.
• Locate it in a convenient location for future add-ons and possible troubleshooting.
• Locate it in an unobtrusive location, which would make it less likely to attract vandals.
• Locate it close enough to your equipment, so it doesn’t result in a voltage drop and dysfunctional locks or cameras.
• Locate it so the wiring isn’t close to other voltage-carrying or noise-generating conductors. Also, locate the wiring in a way that will protect it from damage.

Altronix Interview

Altronix is a leader in providing power supplies for EAC and video surveillance. We contacted Ronnie Pennington, Altronix’s director of sales for the Americas, for his insights on power supplies.

Locksmith Ledger: How would you describe the transitions in power supplies that are occurring in the security industry?

Ronnie Pennington: Today’s security systems are generally highly integrated and deploy more devices over larger physical areas. This has dramatically increased the demand for new and innovative power and data transmission solutions that accommodate new-system installations as well as system upgrades that use existing infrastructure.