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Spider
Guest
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 Posted:
Sun Nov 07, 2004 5:12 pm Post subject:
Biased magnetic contacts on metal (cross posted) |
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Aritech DC103 biased magnetic surface contacts are being used on metal
(ferrous) windows, they are secured using a chemical adhesive.
A number of them are not going into alarm when the window is opened,
possibly due to the frame retaining some residual magnetism, would inserting
an aluminium shim sandwiched between the frame and switch reduce this
effect.
Any help or constructive advice would be welcomed.
Thanks in advance
Ian
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G. Morgan
Guest
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| Posted:
Sun Nov 07, 2004 6:25 pm Post subject:
Re: Biased magnetic contacts on metal (cross posted) |
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On Sun, 7 Nov 2004 11:12:56 -0000 "Spider"
used 15 lines of text to write in newsgroup:
alt.engineering.electrical
| Quote: |
A number of them are not going into alarm when the window is opened,
possibly due to the frame retaining some residual magnetism, would inserting
an aluminium shim sandwiched between the frame and switch reduce this
effect.
|
Yes. You should shim the contact and the magnet to get them as far
away from the ferrous metal as possible.
--
-Graham
Remove the 'snails' from my email |
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jackcsg
Guest
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| Posted:
Tue Nov 09, 2004 6:17 am Post subject:
Re: Biased magnetic contacts on metal (cross posted) |
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"Spider" <Alarmeng@Hotmail.com> wrote in message
news:cmkvvq$u4b$1@news6.svr.pol.co.uk...
| Quote: | Aritech DC103 biased magnetic surface contacts are being used on metal
(ferrous) windows, they are secured using a chemical adhesive.
A number of them are not going into alarm when the window is opened,
possibly due to the frame retaining some residual magnetism, would
inserting
an aluminium shim sandwiched between the frame and switch reduce this
effect.
Any help or constructive advice would be welcomed.
Thanks in advance
Ian
Sounds more like they're not installed correctly. One of the advantages of a |
BMS is that it is very difficult to dummy out the switch with an alternate
magnetic source, if it is correctly installed. I would use a multimeter and
ensure proper operation of the switch itself, the tamper, and that it is
correctly wired. The chances of the metal in the window frame effecting its
operation are...well not unheard of, but slim. I've used them on vault doors
for over 20 years with no loss of magnetic power, and without any spacers.
You may have a couple of bad switches...but I bet the magnet is not the
issue.
Jack
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