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Tann synchronome 5401 smoke
#1
Anyone got a manual for these dinosaurs? I want to know what resistance they give out in fire alarm, normal etc...
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#2
I may be wrong but I've always understood that for automatic detectors it's more the current drawn in alarm that will activate the panel, rather than a resistor being applied across the zone such as in manual callpoints.
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#3
I agree
All posts are of my own opinion and knowledge and do not reflect the views of the Company I work for.
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#4
The way I understood it was the resistance caused by a 'fire' caused more current draw and hence a fire at the control panel? I may be wrong there!

I'll elaborate. Kentec sigma 4 zone. zone 4 is roof voids and plant room. engineer changed a tann synchronome high temp heat in the plant room(hard to test! and from 1990) for an apollo series 65 BR 75 deg c heat and diode base. Panel went into fire with and without new detector connected. found another smoke in 'fire', cleaned, reinserted (nightmare in a void!) and that detector was fine, next one along into fire, cleaned, reinserted, all ok etc until finally it settled down after doing this 3 times. when we changed another heat the panel went into fire again. split the diode in the new heat, let it calm down and everything went back to normal (a panel reboot did not clear the problem!)

are all the 3 smoke detectors in the void faulty? - if so why are they 'ok' after cleaning? why did this happen just after another detector and base were swapped? they were fine before, any ideas?

hence the question about what resistance tann smokes give in normal condition. kentec sigma panels see anything from 100-1000 ohm as 'fire' so maybe they were all a bit dirty and cumulatively after cleaning just about ok?

I know we should change the bases but they are 20 feet above a false ceiling next to vents etc and all working apart from this problem. i'd hate to rip the ceiling apart for detectors that still work 99% of the time. clearly we have informed the site of the problem and the age of the devices. cable checked for earth faults, all cores measure at least 3-4 Meg ohm between each other

any other explanation other than ghosts?
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#5
(10-12-2019, 12:22 PM)rtfm Wrote: I may be wrong but I've always understood that for automatic detectors it's more the current drawn in alarm that will activate the panel, rather than a resistor being applied across the zone such as in manual callpoints.

But according to good old Mr Ohm the current is directly proportional to the potential difference blah blah blah.

I am sure they work in a slightly more fancy way but very simply when in alarm I would have assumed a conventional detector does show a resistance change (>1K at an educated guess) in some way.......otherwise how else would you get the correct change in current draw?
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#6
(12-12-2019, 12:55 AM)Mr C Wrote:
(10-12-2019, 12:22 PM)rtfm Wrote: I may be wrong but I've always understood that for automatic detectors it's more the current drawn in alarm that will activate the panel, rather than a resistor being applied across the zone such as in manual callpoints.

But according to good old Mr Ohm the current is directly proportional to the potential difference blah blah blah.

I am sure they work in a slightly more fancy way but very simply when in alarm I would have assumed a conventional detector does show a resistance change (>1K at an educated guess) in some way.......otherwise how else would you get the correct change in current draw?

This has always been my understanding. 

While it's not exactly a resistance you'll be able to directly measure, technically any load you place on a circuit is something that's making the circuit , ie a connection between +ve & - ve.

I think you're right too that the "resistance" of a detector in alarm would be fairly high. I remember years ago while tracing an alarm that I just couldn't find, my boss at the time told me to check the circuit for voltage drop, because an mcp would always drop the voltage by a volt or two if it was in alarm . I tested his advice by testing a detector and an mcp on a different circuit and, lo and behold, he was right - the mcp in alarm had a measurable difference on the voltage compared to a detector in alarm.
For the record, it was a really, really old metal heat detector that was almost invisible on a metal roof at lifter height, I only found it in the end by tracing and splitting - no measurable resistance on the cables when they weren't connected to the panel except the eol.


In this case, the fact the detector leds were lighting up suggests the problem genuinely was with each individual detector. If it was a cumulative load thing, I'd expect to just see a fire on the panel with no leds illuminated.

As for why it jumped from head to head, that seems to be as simple as the panel only lighting the first led (common on conventional panels in my experience). 
As for why they weren't in alarm before, maybe the circuit wasn't complete before? Why was the old head replaced? Was the eol fitted in the right place? 

Unrelated - is a diode base the right thing to do? Is it an active eol?
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#7
(12-12-2019, 01:53 AM)Monkeh Wrote:
(12-12-2019, 12:55 AM)Mr C Wrote:
(10-12-2019, 12:22 PM)rtfm Wrote: I may be wrong but I've always understood that for automatic detectors it's more the current drawn in alarm that will activate the panel, rather than a resistor being applied across the zone such as in manual callpoints.

But according to good old Mr Ohm the current is directly proportional to the potential difference blah blah blah.

I am sure they work in a slightly more fancy way but very simply when in alarm I would have assumed a conventional detector does show a resistance change (>1K at an educated guess) in some way.......otherwise how else would you get the correct change in current draw?

This has always been my understanding. 

While it's not exactly a resistance you'll be able to directly measure, technically any load you place on a circuit is something that's making the circuit , ie a connection between +ve & - ve.

I think you're right too that the "resistance" of a detector in alarm would be fairly high. I remember years ago while tracing an alarm that I just couldn't find, my boss at the time told me to check the circuit for voltage drop, because an mcp would always drop the voltage by a volt or two if it was in alarm . I tested his advice by testing a detector and an mcp on a different circuit and, lo and behold, he was right - the mcp in alarm had a measurable difference on the voltage compared to a detector in alarm.
For the record, it was a really, really old metal heat detector that was almost invisible on a metal roof at lifter height, I only found it in the end by tracing and splitting - no measurable resistance on the cables when they weren't connected to the panel except the eol.


In this case, the fact the detector leds were lighting up suggests the problem genuinely was with each individual detector. If it was a cumulative load thing, I'd expect to just see a fire on the panel with no leds illuminated.

As for why it jumped from head to head, that seems to be as simple as the panel only lighting the first led (common on conventional panels in my experience). 
As for why they weren't in alarm before, maybe the circuit wasn't complete before? Why was the old head replaced? Was the eol fitted in the right place? 

Unrelated - is a diode base the right thing to do? Is it an active eol?

ta monkeh - the heat head was replaced as it was a high temp heat and the engineer found it hard to test without a mains tester (and it's from 1990) - it is possible that the detectors in the void were not on the system before but not likely as the e-o-l is in place at the end of the circuit so without a complete circuit the system zone would have been in fault (and it wasn't)

it is not an active e-o-l so a diode base is not ideal BUT:

1 - the heads are in voids or a locked plant room so unlikely to be accessed by unregulated people
2 - we locked the new heads into the diode bases with a 1.5mm allen key
3 - i'd rather lose one detector (if it was removed) than a load of devices further down the circuit

of course ideally we'd change the e-o-l to active lcmu but it's 20 foot above a ceiling void false ceiling!  

thansk for everyone's input!
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#8
Technically (!!) it's still wrong to leave the diode in the base if it prevents a fault when the head is removed, but I'd agree with your reasoning and would probably do the same.
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