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Subject: Re: Security System Sensors
Date: Thu, 31 Oct 2002 16:24:20 -0000
NNTP-Posting-Date: 31 Oct 2002 16:23:05 GMT
X-Newsreader: Microsoft Outlook Express 5.50.4133.2400
24 hr cicuit is NC continuous loop. The 24hr loop activates an internal
alarm whereas the main loop (also NC) activates the external sounder.
Systems are made up of many types of sensor i.e. PIR, door contacts,
vibration sensors which would constantly trigger while alarm set. Hence
separate 24 hr loop.
These things have to be designed to meet National Standards. If its to use
in your own home you can ignore the 24 hr loop if you like. I'm sure 4 way
cable is available and you just ignore the 24hr loop connections.
"Douglas J Petican" wrote in message
> If I understand correctly, the 24HR loop is used when the alarm system is
> deactivated to detect tampering with the system? Are all the sensors
> in series?
> Wouldn't NC as oppose to NO sensors achieve the same thing? The response
> an open circuit would then depend on whether or not the alarm system was
> activated. In other words always monitor the sensor loops. Although the
> difference between tamper and alarm would be blurred, but from a practical
> view isn't that the same thing?
> Do sensors come in just 4-wire versions?
> Thanks, Doug Petican
> "Dave" wrote in message
> > Hello Douglas,
> > The 24 hr loop is simply a continuous loop around the system. If anyone
> > attempts to disable the alarm during the daytime (or whenever the alarm
> > not set) by cutting the cable or removing a cover this loop is broken
> > sounds an internal alarm. I hope that made sense.
> > Dave.
> > "Douglas J Petican" wrote in message
> > news:firstname.lastname@example.org...
> > > I'm working on the design for a security system. I've noticed that
> > > sensors have 6 terminals: 2 for power, 2 for NO/NC connection, 2 for
> > > connection.
> > >
> > > What does the 24HR connection do?
> > >
> > > Thanks, Doug Petican
> > >
> > >
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