Ask the Experts | Ask the Electronic Access Ace

Question:

What power supply should I use for my access system?

Answer:

You need to know what your ultimate requirements are before you can make an informed decision.

First, you need to decide what voltage: 12V or 24V –this will normally be determined by what products you are using or what is currently being used. A normal benchmark is that modern Access Control and CCTV tend to be 12V (but most devices can also run at 24V as well).

Second, determine the number of devices in the system and the power requirements for each. This information is necessary to determine the size and quantity of the power supplies and how many
devices they will run. Amp draw is typically found in the manufacturers cut sheets or their website. Amp draw is different at each selected voltage 12 or 24.

Example:
An HES 9600 electric strike has a 450 mA current draw at 12 VDC and 250 mA current at 24 VDC.

Third, calculate your amperage – when using a device that is permanently powered (such as a maglock or a failsafe continuous duty electric strike) my recommendation is to use a power supply that provides 20 to 50 percent more amperage to the devices being powered.

Example 1:
2 maglocks each requiring 480 mA of current, totaling 960 mA. I would suggest a power supply that provides at least 1.4 amps of current.

Example 2:
Note: 1000 mA = 1 amp

Magnetic lock 1 350 mA or .35 amps
Magnetic lock 2 350 mA or .35 amps
Keypad controller 1 400 mA or .4 amps
Keypad controller 2 400 mA or .4 amps
Total: 1500mA or 1.5 amps
Recommended Power Supply: 1.8 amps – 2.25 amps (20 – 50% more than the devices total)

 

In this example, a 1.8 amp power supply would be the minimum but I would recommend a 2 to 2.5 amp for this access control system.

Last, you need to decide if you want to have battery backup should the main power be interrupted. This ability is standard with most access control power supplies. Installing batteries will add cost to your job and they will need to be maintained throughout the life of the system.

This is a very basic overview of power supplies, but if you need any further advice then please don’t hesitate to call your local IDN salesperson they can advise you on the ideal power supply to suit your system requirements.

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