Relays

[Abdi12]

Hi every one, nice to be back again.

I am trying to post a question with diagrams, unfortunately this system will only paste letters, not diagrams.

I wonder if Graham or Buzzard or indeed any other engineer will let me send me their email so I can send you my question.

This is my email:furre@aol.com.

Nice one.


By the way this is how it comes out when I paste it to this system.


Relays (Volt Free Contacts)



Monitoring two relays simultaneously:



Method 1:

(Gas Panel)



Fire Relay                             Fault Relay
nc    c    no                             nc     c    no





My question is. Is there a method to connecting the two relays up. In this example the common is connected to n/c and n/o to common.
Also in the house alarm I suspect that is where they will put the switching resistors is that right? Again why use the resistors?

I do understand how relays work when they operate individually i.e. using alarm relay to shut down lift or boiler….

Aux24vdc                        Alarm                              Aircon/Lift
  +     -                            nc    c   no















Method 2:                        



(Gas Panel)                                                                                          House Alarm





Remote Relay                                        Fault Relay
Nc      c    No                  Ω                     Nc     c   No



`Ω




In the second method two commons are connected, then you have one resistor between n/0 and n/c and another between common n/c.

My question is why are the connection different and also the resistors does it matter whether they are installed in the gas in one panel or the other.


I would be very grateful if you could perhaps give me an assist on this topic.

I look forward to you feedback.

Kind Regards
A.Furre

[Graeme]

Method one

If i read you right you need a normally closed connection over two relays with the fault being inverted  i.e normally closed is open until fault.

then you could go  connect to fire NC , link between fire Common and Fault common  then other end of connection to fault NO. If if not inverted to fault NC.

with your intruder it will have resistors to let the control panel know if devices are open,closed,short or open circuit and you need to use resistors as each condition will give a different resistance reading.