Powering Up Your Access Control System with Command Access

Choosing the right power supply varies depending upon the manufacturer and the type of lock(s) and access control hardware. The wire run can be extremely important if distances are significant.


Command Access linear power supplies are UL 294 Listed, and most are CSA International Certified. The solid state design eliminates mechanical relays, providing dry contacts to trigger the input of current.

The Command Access switching power supply, SW4, is rated at 2.4Amp @27VDC continuous power output. The output voltage is adjustable from 24 to 27VDC. There are four fused solid-state inputs and outputs.

The SW4 is designed for solenoid lock/unlock operation in mortise, cylindrical or exit device trim having each of the four outputs rated at a maximum of .6Amp each. There is an alarm link for connection to a Fire Department panel.

Linear power supplies are available with one Amp to five Amps. They are designed as an “all around” power supply able to provide the necessary high current in-rush for powering electric latch pullback, as well as providing “safe” power for electrified locks, electric strikes and magnetic locks. Some of the linear power supplies are equipped with adjustable output voltage, battery charging and multiple outputs. All of the linear power supplies are equipped with a light tube indicating operation when the enclosure is closed.

The Command Access PS1N one Amp, single solid state input/output linear power supply produces 24VDC of filtered and regulated power using a 56 watt transformer. The input is designed to be triggered by a dry contact. Having one large capacitor, the PS1N can deliver the high current in-rush necessary to operate one or two simultaneous electric latch retraction exit device(s).

The PS2 and the PS2BB are two versions of the two Amp power supply. They have sufficient power to operate two latch pullback exit devices using the two independent inputs/outputs. These power supplies are equipped with one large capacitor to insure sufficient inrush surge. The circuit board is equipped with thermal overload sensing. This reduces the risk of failure due to overheating and intelligent short circuit detection and isolation that detects shorts faster fuses.

The PS2 does not offer battery backup and comes in a 10” by 10” by 4” enclosure. The PS2BB offers battery backup/charging circuit with zero voltage drop at power loss. There is an audible alert when the power supply circuitry senses AC power failure and low battery. Battery backup requires two 12V 7Amp hour gel cells that are purchased separately. The PS2BB comes in a 12” by 15” by 4” enclosure.

There four versions of the PS5, a five Amp @ 24VDC linear power supply equipped with a battery charging circuit. Batteries are charged at 27.6VDC, while the output voltage is adjustable from 24 to 27VDC.The power supply options vary by the number of inputs/outputs. The PS5 has one (output only), the PS5-4 has four, the PS5-6 has six and the PS5-8 has eight independent inputs/outputs.

The total output rating is five amps and is divided by the number of outputs to determine the amperage per output. For example, the PS5-4 has four outputs, each have an output rating of 1.25Amps with the PS5-8 having each output rating at .625Amps. The solid state inputs are available as dry contact sensing only. Two large capacitors provide sufficient inrush surge for multiple electrified latch retraction devices.

Choosing the right power supply varies depending upon the manufacturer and the type of lock(s) and access control hardware. The wire run can also be extremely important if there is significant distances. Note: In a future article, we will discuss wire and cable.

To eliminate problems before they occur, factor in at least 10 percent more amperage than the requirement of the electrified lock hardware and an additional 10 percent for variation in the power supply. In power supplies, it is better to have extra power.

For more information, contact your local locksmith distributor or Command Access Technologies, 22901 La Palma Ave., Yorba Linda, CA 92887. Web Site: http://www.commandaccess.com.

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