Re: PIR types - who knows the difference between lighting optimised PIRs and security optimised PIRs?

["Simon Coates" <ecolume@xxxxxxx>]

Chris,

I'm using separate PIR detectors - ceiling mount occupancy PIRs and corner
mounted security PIRs.  The occupancy PIRs couldn't be used for security
because they are too sensitive and would trigger a false alarm.  Security
PIRs have pulse count etc... and circuitry to account for things like
background heat, sunlight to minimise false alarms.  There are even quad
pyro detectors where all 4 pyros have to be triggered for the PIR to
switch.
Basically alarm type PIRs aren't any good for occupancy detection and
vice-versa.

Best thing to do is keep your security system separate from your HA
sensors.

The occupancy PIRs I'm going to use in my house are very sensitive and will
trigger with slight movement.  Certain, larger rooms will require 2
detectors to cover the whole area.  I'll send you some info on them.


Simon


----- Original Message -----
From: Chris Langridge <chrisl@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: 27 November 2001 18:40
Subject: [ukha_d] PIR types - who knows the difference between lighting
optimised PIRs and security optimised PIRs?


> I'm doing some research about PIR's. Have been talking to Philips who
do a
> very nice range of flush mount devices. Then I discovered (as usual)
that
> there's a whole bunch of stuff I'm not clear about.
>
> According to Philips the PIRs built for lighting control are more
sensitive
> than those used for security. The reason of course, is false alarms,
and
the
> fact that people wathcing the telly don't move as much as bandits.
>
> If this deifference in sensitivity is the case, what are you guys
using to
> control lighting AND security?
>
> Also: The Philips 12 volt units have an inbuilt timer. They need three
wires
> (live, neutral and switch). They are normally open, and close when
movement
> is detected. Depending on how the timer has been set, the contact will
stay
> closed for say 5-30 minutes. Now I thought most PIR's purely provide a
> signal which the HA controller will use according to it's own logic. I
had
> never thought that a contact would be closed for say ten minutes and
then
> released. Have I missed something critical here? Can Comfort or HV
handle
> this kind of input, and what kind of processes are you guys using to
control
> lighting if using standard (is there such a thing!) PIRs.
>
> Sorry if this is all very basic - I'm just getting upto speed on
'sensors'
> and have not even purchase my HA interface yet.
>
> Thanks
>
> Chris
>
>
> For more information: http://www.automatedhome.co.uk
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