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#343 - 01/16/01 06:31 PM end of line  
don  Offline
Junior Member
Joined: Jan 2001
Posts: 2
Ontario
what is end of line resistor for in a fire alarm system


Work Gear for Electricians and the Trades

#344 - 01/16/01 07:35 PM Re: end of line  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
supervision of the circuit [Linked Image]


#345 - 01/16/01 09:49 PM Re: end of line  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
where is usually the Q... [Linked Image]


#346 - 01/17/01 07:45 PM Re: end of line  
Tom  Offline
Member
Joined: Jan 2001
Posts: 1,044
Shinnston, WV USA
Sparky,

I guarantee that the resistor will be in the last box you look in, at least if you have any sense at all. [Linked Image]


Few things are harder to put up with than the annoyance of a good example.

#347 - 01/21/01 09:22 PM Re: end of line  
Scott35  Offline

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Member
Joined: Oct 2000
Posts: 2,707
Anaheim, CA. USA
Don,

The End Of Line [or Loop] Resistor AKA EOL Resistor is what loads the zone's loop circuit in normal operation.

The typical EOL resistor would be 2K ohm and connected to TTL logic gates. The circuit's operating voltage is like 5 VDC, so the current through the loop is 2.5 milliamps [0.0025 amps].

What this does is sets up a constant flow of current at a certain level. If a sensor trips and closes the N.O. contacts inside of it, which are wired in Parallel for each device, this causes the loop current to rise above the 2.5 Ma level and activates the alarm.

On the same note, if someone tampers with a sensor and causes the N.C. contacts which are wired in series with all devices to open, this will cause the loop current to stop flowing and will also activate the alarm. Same will happen if the loop's wires are cut.

If you need more info, let me know!! I am back from the Honeymoon and ready to write again!!

Scott. "S.E.T."


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

#348 - 01/28/01 08:32 AM Re: end of line  
dandy467d  Offline
Junior Member
Joined: Dec 2000
Posts: 8
auburn, ny usa
Your reply is correct for security alarm systems, not for fire systems. Loss of the supervisory voltage due to cut wire, missing device, etc. will give you a zone trouble, not a alarm condition.


#349 - 01/31/01 05:19 PM Re: end of line  
Scott35  Offline

Broom Pusher and
Member
Joined: Oct 2000
Posts: 2,707
Anaheim, CA. USA
Dandy:

Glad you caught that one! For some reason I saw Security Alarm System's EOL Resistor when I read the original question <]:-)..

I have only done Security / Burglar Alarm systems, where the EOL Resistor and the zone's loop functions as I posted. Any Fire / Life / Safety systems for the Commercial Projects we do are sub'ed out to other ECs that are familiar with the existing systems [typically Simplex], so they get all the compatable strobes, etc. and programming according to that setup.

Is the EOL Resistor's function on F/L/S systems similar to the Security system's? - To have an X value of current flowing steadilly through the loop during normal operation [functioning NAND or NOR gates will be "Inverted" (NOT Logic or Logic 0) with EOL in circuit], or do the EOL Resistors become connected when the remote device trips [alarm], which would make the logic Gates AND, OR or possibly XOR?

Any info is helpful..


Scott. "S.E.T." [Linked Image]


Quote
Originally posted by dandy467d:
Your reply is correct for security alarm systems, not for fire systems. Loss of the supervisory voltage due to cut wire, missing device, etc. will give you a zone trouble, not a alarm condition.


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!


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