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  • Interference with alarm systems HELP

    Hi group,

    I recently installed a door alarm system using RFID access reader as the alarm controller and a normally closed (NC) door magnetic sensor as the alarm switch. It works perfectly after the installation until few weeks later false alarms occurs randomly particularly in the morning when I turn on the fluorescent lights, the alarm triggers.

    I rechecked and double checked the alarm wirings and configurations based on the manual/diagram provided by the manufacturer but the false alarms still occurring randomly and without a pattern.

    Can anyone in the group help me determine the possible causes of these false alarms and what solutions I can take.

    Many thanks

  • #2
    Take a look at the circuit this system is using for power and ensure that it is not the same circuit that the lighting are on. Fluorescent lights can cause a slight surge when they come on and this may be causing the problem. Another thing to look at is if any of your wiring paths run parallel to any electrical wiring. Electrical circuits will give off electromagnetic field which can impact the alarm systems.
    -Jedi-
    Semper Paratus

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    • #3
      What kind of controller are you using? What is the power supply for the controller? Although Jedi is correct, with a regular alarm panel this is a very unlikely scenario. Can you tell what else is causing these false alarms?
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      • #4
        Interference with alarm system

        Originally posted by Jedi View Post
        Take a look at the circuit this system is using for power and ensure that it is not the same circuit that the lighting are on. Fluorescent lights can cause a slight surge when they come on and this may be causing the problem. Another thing to look at is if any of your wiring paths run parallel to any electrical wiring. Electrical circuits will give off electromagnetic field which can impact the alarm systems.
        According to the electrician my alarm systems AC supply is wired home-run to a breaker box but though the alarm circuit has its own AC circuit breaker, the latter is still housed to a single breaker box with multiple breakers in it, I guess most of it are for lightings and outlets. Can this also affect electrical surge?

        With regards to my wiring paths, only the AC supply runs parallel to other AC wirings of the room. All alarm terminals and switch wirings are contained only in the metal door and I am using a stand-alone access controller with built-in alarm system.

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        • #5
          Originally posted by integrator97 View Post
          What kind of controller are you using? What is the power supply for the controller? Although Jedi is correct, with a regular alarm panel this is a very unlikely scenario. Can you tell what else is causing these false alarms?
          I am using a stand-alone RFID 125KHz access control system with built-in alarm system. My power supply is a 12VDC regulated uninterrupted power supply (DC-UPS) installed on top of the door.

          Its only light switching which triggers the false alarm.

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          • #6
            I assume the alarm/access panel has a battery backup?
            Does it happen every time you turn on the lights?
            If the answer to both is yes, try shutting off the ac power to the alarm/access panel before you turn on the lights.

            If you still have a false alarm, the problem is likely induced in the wiring, probably too close to the lights or the lighting power cables.

            If you don't have a false alarm, it's probably coming from a surge from the ac power distribution panel. You either have extremely poor power or improperly wired electrical; or you have a bad access/alarm control panel. I've never seen input power do that without damaging the panel, but for S & G's we'll consider it a possibility.

            In 18 years of doing access control and alarms in commercial and industrial environments I've never had routine false alarms from either of those scenarios. Unless you find a serious electrical problem, I would suspect the alarm/access panel itself.
            sigpic
            Rocket Science
            Making everything else look simple, since 1958.


            http://my.opera.com/integrator/blog/
            One Man's Opinion

            The Future. It isn't what it used to be.

            Comment


            • #7
              Originally posted by integrator97 View Post
              I assume the alarm/access panel has a battery backup?
              Does it happen every time you turn on the lights?
              If the answer to both is yes, try shutting off the ac power to the alarm/access panel before you turn on the lights.

              If you still have a false alarm, the problem is likely induced in the wiring, probably too close to the lights or the lighting power cables.

              If you don't have a false alarm, it's probably coming from a surge from the ac power distribution panel. You either have extremely poor power or improperly wired electrical; or you have a bad access/alarm control panel. I've never seen input power do that without damaging the panel, but for S & G's we'll consider it a possibility.

              In 18 years of doing access control and alarms in commercial and industrial environments I've never had routine false alarms from either of those scenarios. Unless you find a serious electrical problem, I would suspect the alarm/access panel itself.

              To give you a more detailed view of the project, I installed 5 access panels in 5-doors and they all are connected in 1 ac breaker power source but individual UPS. When I turn on about 10-15 fluorescent lights at the same time the alarm of all 5-doors will also burst at the same time. But this does not happen every time I turn on the lights sometimes it doesn't trigger the alarm. At any rate, I will try first your suggestion and isolate the AC supply and just use the battery. "Many thanks integrator97"

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              • #8
                I've had this happen with video signal before and it was because the UPS and the DVR had different potentials to ground. You may want to take a look at that and if it works on the DC batteries just fine then that is most likely the issue.

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