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FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Technical Advice => Topic started by: Benzerari on January 24, 2007, 04:42:29 PM

Title: Head removed monitoring in a Two-Wire conventional fire alarm system
Post by: Benzerari on January 24, 2007, 04:42:29 PM

Hi all;

The head removed in normal conventional fire alarm system is achieved through many ways either using active EOL or normal resistor EOL with diode fitted in the base of each detector. but the two wire system is completely a different case, it can not use any of the ordinary ways so how is it done then?

Thank you

Benzerari

Title: Head removed monitoring in a Two-Wire conventional fire alarm system
Post by: Benzerari on March 10, 2007, 10:03:59 PM

Hi all;

Is there any one please who can give us a bit of light of how a twin wire conventional system is monitoring the head removal process?

and thank you in advance

Benzerari

Title: Head removed monitoring in a Two-Wire conventional fire alarm system
Post by: Graeme on March 11, 2007, 12:14:28 PM

In the case of the Manufacturer that i use,the detector base has a module which monitors the cable going out and generates pulses if a detector is removed.

Compatable control panels recognise the pulses given and enter fault condition.

The bases are wired in parallel,so no loss of power occurs when a head is removed and the eol is a resistor.

Title: Head removed monitoring in a Two-Wire conventional fire alarm system
Post by: Benzerari on March 11, 2007, 04:15:39 PM

Quote from: Graeme

In the case of the Manufacturer that i use,the detector base has a module which monitors the cable going out and generates pulses if a detector is removed.

Compatable control panels recognise the pulses given and enter fault condition.

The bases are wired in parallel,so no loss of power occurs when a head is removed and the eol is a resistor.

Thanks Graeme for this micro light, that is really helpful

Do you mean the module inside the base is short circuited or disbaled when the head is fitted?

also what kind of pulse does this module delivers, its amplitude is it some thing like +5Vdc above the existing 24Vdc of detection circuit or +5Vdc above 0Vdc.....etc ?

the other enquiry is that how that pulses are not affected when the voltage is reversed in fire condition of two-wire system?

Title: Head removed monitoring in a Two-Wire conventional fire alarm system
Post by: Graeme on March 11, 2007, 06:17:08 PM

Hi Ben


just to save time see link

thanks

g

http://www.apollo-fire.co.uk/PDFs/PP2060%20AlarmSense%20Product%20Guide.pdf

Title: Head removed monitoring in a Two-Wire conventional fire alarm system
Post by: Benzerari on March 12, 2007, 11:04:15 AM

Thanks Graeme for this macro light