30 devices missing due to short circuit in the loop ?

[Wiz]

Benz any beam detectors on that loop?

Good call GregC!

[Benzerari]

Benz any beam detectors on that loop?

So what's the relationship between beam detectors and this issue?

[GregC]

We had a problem a few years ago with beam detectors on a loop.

If I remember correctly, there were random activations of isolators that caused open circuit faults at the panel but were never seen on the circuit when we went ot test.

It turned out that in the small print of the installation data you have to fit isolators either side of the beam betectors, when the panel was refreshing its checksum, the initial start up current draw of the beam ddetectors was enough to activate an isolator, by having an isolator either side it cured the problems.

Might not be what you are experiencing but given you have 30 devices missing I would suspect you have a beam detector or similar device thats causing the loop to overload and bring in the isolators.

[Big_Fella]

Indeed, it might be worth finding out exactly what is on the loop and doing a loop calculation to see if the loop is overloaded, as this will cause spurious faults, and is quite often a common problem.

Or try breaking the loop half way roughly, and running both legs on two separate loops cards, thus halving the current requirement per loop.

What type of beam detectors is it? manufacturer? reflective type or not?

Are they loop powered or conventional type via input modules?

[Benzerari]

We had a problem a few years ago with beam detectors on a loop.

If I remember correctly, there were random activations of isolators that caused open circuit faults at the panel but were never seen on the circuit when we went ot test.

It turned out that in the small print of the installation data you have to fit isolators either side of the beam betectors, when the panel was refreshing its checksum, the initial start up current draw of the beam ddetectors was enough to activate an isolator, by having an isolator either side it cured the problems.

Might not be what you are experiencing but given you have 30 devices missing I would suspect you have a beam detector or similar device thats causing the loop to overload and bring in the isolators.

Possibly, but technically speaking, how a beam detector causes short circuit isolators to trigger in either ways?

[Benzerari]

Indeed, it might be worth finding out exactly what is on the loop and doing a loop calculation to see if the loop is overloaded, as this will cause spurious faults, and is quite often a common problem.

Or try breaking the loop half way roughly, and running both legs on two separate loops cards, thus halving the current requirement per loop.

What type of beam detectors is it? manufacturer? reflective type or not?

Are they loop powered or conventional type via input modules?

The loop was sitting OK for 3 years or so with no problem, why it should be over loaded only now?

But for the type of the beam still need to find out!

[Big_Fella]

OK, thought there may have been some recent alterations or something which could shed some light on it.  I know the loop card flashing LEDs have been mentioned, but have you tried swapping out the loop card for another?

[Big_Fella]

With the Apollo devices, are the isolators integral to the devices or standalone isolators? We've had problems with isolators in Apollo call points in the past causing rogue problems.  Replacement of the faulty device (once traced) overcame the problem.

[GregC]

The problem with beam detectors and isolators is that beam detectors take a higher start up current that they do in normal operation, when a panel carries out its checksum count it powers down the loop and re energises the devices this is what caused our problem, it wasnt every night but common enough for us to pinpoint the problem.
Our system was running for some time before these faults started to appear


In your situation I would be looking at the beam detectors to make sure isolators are fitted either side, maybe an isolator is your problem?

[Benzerari]

OK, thought there may have been some recent alterations or something which could shed some light on it.  I know the loop card flashing LEDs have been mentioned, but have you tried swapping out the loop card for another?

I didn't swap the loop cards over, since they were all flashing ok, and also the left legs of the loops had short circuit which confirms he problem relies within the cabling rather than the loops card...

[Benzerari]

With the Apollo devices, are the isolators integral to the devices or standalone isolators? We've had problems with isolators in Apollo call points in the past causing rogue problems.  Replacement of the faulty device (once traced) overcame the problem.

The short circuit isolators are above detectors, have found in the first visit only one triggered, which  means the next one could be the that end of the loop, but the day after was OFF, up till now we don't know what caused it to trigger, it's now an open circuit...

[smoke monkey]

Water water everywhere and not a drop to drink.

Ask yourself this...what causes a loop fault ?

Faulty device
Faulty Loop Card ( sometimes faulty due to a field device or lightning strike )

When you have checked the probable..look at the impossible.