Max Current Draw And Connected Devices

[Guest anguscanplay]

then switch off the mains from your part 'p' compliant and certified spur

tee hee

OMG the`ve moved disneyland

[arfur mo]

Arfur,

Pay attention

I know have invaded France ocassionally, but not in recent times.

So, Part P??

part 'P'aris

regs

alan

[arfur mo]

This is one for arfur really

the trigger doesnt power the external sounder so you dont need to add that 425ma figure into the 500ma max draw - never measured it at the trig terminal ( but will do tommorow) but it`ll be tiny

for goodness sakes what are you on about now my little apprentice? as it does draw drive current if in sab mode, scb mode runs off the bells own battery in the bell.

for Drillers needs the current drawn in 'off' and 'set' modes are the most important to establish, as this decides how long the standby batteries will last for in a prolonged power cut, or being France before the generator cuts in.

we don't need 12 hours back up when the alarm is ringing (do we? ) so we can virtually discard the draw of the siren/s when sounding as short term any short fall of the psu will be aided by the battery, so we need to decide more on how long the system would continue to sound in power out situations, and that would depend on the risk covered, but a calculation of 1 hour would suit most common installations imho.

regs

alan

[Driller]

Thanks for the replies Angus and Arfur. If I may Arfur are you both talking about the same part of the questions? [ducks] I have the impression that Angus is talking about the 500mA limit on the bell trigger (which is fused) so if the SAB and internal sounder go off and together draw more than 500mA (although as Angus says perhaps not as simple as this?), even though the PSU goes up to 1.4A/1.0A, the bell trigger fuse might blow, so important to take this into account in an alarm situation?

short term any short fall of the psu will be aided by the battery

Ahhhhh, the penny drops! Now that I didn't know. OK, I see now how important it is to test the total draw on all devices for fear of de-juicing the battery.

Do you have a view Arfur on the phrase "Max power output 1.4A and 1.0A grade 2" ?

as this decides how long the standby batteries will last for in a prolonged power cut, or being France before the generator cuts in.

heh, heh Did you know that they collect the rubbish here 3 times a week as well? Looxury!

[Guest anguscanplay]

for goodness sakes what are you on about now my little apprentice? as it does draw drive current if in sab mode, scb mode runs off the bells own battery in the bell.

regs

alan

the bell trigger to the external sounder is just a switch wire not load

what I was saying - the panel has 500ma for aux, 500ma for bells and 500ma to trigger with, the power for the internal alarm ( connected across 12v and trig ) is seperated from the power that runs the external box in an alarm ( connected across 12v and 0v )

either that or theres 500ma missing somewhere and panels shouldnt have 1amp fuses in the bell line LOL

[breff]

This is one for arfur really

the trigger doesnt power the external sounder so you dont need to add that 425ma figure into the 500ma max draw - never measured it at the trig terminal ( but will do tommorow) but it`ll be tiny

Correct, the current will be drawn from the 12v and 0v permanent supplies.

[arfur mo]

Thanks for the replies Angus and Arfur. If I may Arfur are you both talking about the same part of the questions? [ducks] I have the impression that Angus is talking about the 500mA limit on the bell trigger (which is fused) so if the SAB and internal sounder go off and together draw more than 500mA (although as Angus says perhaps not as simple as this?), even though the PSU goes up to 1.4A/1.0A, the bell trigger fuse might blow, so important to take this into account in an alarm situation?

Ahhhhh, the penny drops! Now that I didn't know. OK, I see now how important it is to test the total draw on all devices for fear of de-juicing the battery.

Do you have a view Arfur on the phrase "Max power output 1.4A and 1.0A grade 2" ?

heh, heh Did you know that they collect the rubbish here 3 times a week as well? Looxury!

as for the bell current being limited by the 500? ma fuse (many panels have a 1 amp 'bell' fuse) your looking at it from the wrong perspective.

the fuse rating is to protect the main boards pcb tracks from fire or burn out in case of a direct short placed across the output terminals, it is not to govern against you connecting say 16 sirens off it

just do the test i outlined earlier and you will be fine, simply devide the current drawn into the battery amp hour size to get how long the system will work of batteries.

as for 1.4/1 part 2 well your in France and tbh they care far less for any regulations or compliance to authority than even i'm supposed to do - so why worry?

regs

alan

[magpye]

Why not just fit an additional PSU, split up the power between panel & PSU and don't worry about it any more, much better in the long run?

[Driller]

OK so to round this whole thing up then (and sorry for the long post):

Why not just fit an additional PSU, split up the power between panel & PSU and don't worry about it any more, much better in the long run?

Thanks for the suggestion Magpie and absolutely, this would solve the problem very simply. But I can't get one in France and won't be going over to the UK for some time. Also my system only has 4 PIR's (10 door/window contacts) and an external and internal sounder-I can't believe that the main panel can't handle this but I've had difficulty convincing myself.

the trigger doesnt power the external sounder, it`ll be tiny,the bell trigger to the external sounder is just a switch wire not load

Correct, the current will be drawn from the 12v and 0v permanent supplies.

Ok so this means I can connect the internal sounder to the aux 12V+ but also importantly internal and external sounders to the (one and only) bell trigger without carbonising anything.

as for the bell current being limited by the 500? ma fuse (many panels have a 1 amp 'bell' fuse) your looking at it from the wrong perspective.

the fuse rating is to protect the main boards pcb tracks from fire or burn out in case of a direct short placed across the output terminals, it is not to govern against you connecting say 16 sirens off it

Just to quote the (selected) specifications of my panel (especially "individual 12V outputs":

PSU Max total load (from AUX, Bell, Trigger and STU outputs) 1.4A (Grade 2 1.0A)

Individual 12V outputs

Bell +12 V = 500mA max

Both Aux+ combined =500mA max

Trigger Header +12 V 100mA max

Switched outputs

Bell Trigger can sink 500mA max

Strobe trigger can sink 500mA max

Trig output can sink 30mA max

Fuses

Mains 200mA

Battery 1.0A

Aux 500mA

Bell 500mA

just do the test i outlined earlier and you will be fine, simply devide the current drawn into the battery amp hour size to get how long the system will work of batteries.

Yes, I will definately do that. It seems like the only way to be sure.

as for 1.4/1 part 2 well your in France and tbh they care far less for any regulations or compliance to authority than even i'm supposed to do - so why worry?

How did you know that much about France Arfur?

[arfur mo]

just a caution, i would add observe the difference's between an internal siren/sounder having electronics and driven from a 12 volts source, and an extension speaker which are normally 8-16 ohms, and driven by a signal from the extension speaker output, as get a speaker across 12 volts in alarm condition and an internal barbeque's could happen.

in reference to 1.4 amp or 1 amp for grade 2, i'm assuming it's to do with grade 2 rating, which is a fairly recent instigation and demands longer stand-bye times than the older BS 4737 criteria, so hence being lower rated available current for a given battery size to achieve 12 hours under grade 2.

personally fro what you have attached i don't think you need an additional psu, no harm in fitting it b ut how will you devide the power? if you simply add the psu to the panel supply you effectively will have say 2 amps available (1amp from panel 1 amp from psu) before a fuse will blow, more than enough to cause a fire o a 1 amp rated cable core if a short occurs, so for your own safety sakes i'd just use the panels supply.

name the panel used and model and others will clarify it's capabilities.

as for knowing about france - lost count of the times stuck in ports waiting for this or that strike to end

regs

alan