"Alarm Gross" HKC Panel

[Eugene's DIY Den]

My HKC10W70 panel activated at 2.30 am and sent me three SMS messages. The first was the the alarm zone activated, the next was "alarm gross" and the third told me I had unset the alarm. What does "alarm gross" mean. I don't think I've ever seen that before on alarm activation. The cause of the alarm activating was a contact opening. Usually I have lots of trouble with these sticking on windows I never open rather than opening spontaneously, even if I replace with new ones.

[james.wilson]

its a gross attack. your panel will report that its different to a pulse attack. Basically means 1 big impact rather than a few smaller ones

but depends how you have it wired if you have a contact in series with the shock sensor or did you bang the window to open it?

[Eugene's DIY Den]

3 hours ago, james.wilson said:

its a gross attack. your panel will report that its different to a pulse attack. Basically means 1 big impact rather than a few smaller ones

but depends how you have it wired if you have a contact in series with the shock sensor or did you bang the window to open it?

No, they're just simple reed switches with magnets. Problem is I have 16 of them wired in series, so identifying which one triggered would be a problem. However I have a radiator located under a window behind curtains and if heat was trapped and caused a large temperature increase, this may be the issue if the magnet/contact spacing is too great and the magnet is weakening at that contact. However all the 16 sensors have a gap of a cm or so, but the alarm is installed 4 years and this is the first time I've had a false alarm on this zone.

Edited April 19, 2021 by Eugene's DIY Den

[james.wilson]

sounds like high res then. Whats the loop resistance of the circuit. Im assuming its double pole. You shouldnt have 16 of anything on 1 circuit tho

[al-yeti]

2 hours ago, Eugene's DIY Den said:

No, they're just simple reed switches with magnets. Problem is I have 16 of them wired in series, so identifying which one triggered would be a problem. However I have a radiator located under a window behind curtains and if heat was trapped and caused a large temperature increase, this may be the issue if the magnet/contact spacing is too great and the magnet is weakening at that contact. However all the 16 sensors have a gap of a cm or so, but the alarm is installed 4 years and this is the first time I've had a false alarm on this zone.

You should have gone with points in that case some how would work on the wiring aswell then you can identify which is the problem 

 

Messy dude

[Eugene's DIY Den]

I replaced three contacts which didn't reliably open every time a window was opened during a test. Tapping some of the contacts worked and they'd open a few times, but would then get sticky again. I'll probably have to replace them in another few years again, that's as long as they last. All contacts that give trouble are on windows that never open. Two theories as to why. One: The few mA of current flows when contacts are closed for months or years causes a build up of material that permanently causes the contacts to grip together. Even if they have stuck together and tapping releases, there's still a locking effect. Two: Contacts become permanently magnetised just like a screwdriver when held shut for long periods, causing them to stick. Opening and closing regularly demagnetises them. The material they're mad from should have a low magnetic remanence, but maybe it's just enough to cause stickiness.

Edited April 20, 2021 by Eugene's DIY Den

[Eugene's DIY Den]

If remanence is the cause it should be possible to demagnetise using a hand held demagnetising tool.