jmsa7 Posted September 18, 2011 Posted September 18, 2011 Hello everybody, I just got a job with fire alarm panels so there is still a lot of stuff I need to learn. Wonder if someone can explain me what is a earth fault, what can cause it and ways of troubleshooting it? Why do we need the earth in the 1st place? In all our panels the earth is connected to the negative terminal (0V) at the panel. Does the earth terminal play the same role in a DC and AC system? Thanks for your time.
MrHappy Posted September 18, 2011 Posted September 18, 2011 Wonder if someone can explain me what is a earth fault, what can cause it and ways of troubleshooting it? electrical installation with an earth fualt or earth fault displayed on fire panel ? Why do we need the earth in the 1st place? In all our panels the earth is connected to the negative terminal (0V) at the panel. I assume your product is degined with the earth tied to ov a the cabinet is metal ect... Mr Veritas God
jmsa7 Posted September 18, 2011 Author Posted September 18, 2011 electrical installation with an earth fualt or earth fault displayed on fire panel ? Is there any difference? Wouldn't an electrical installation (DC in this case) with an earth fault cause an "Earth Fault" displayed on the Fire Panel? I assume your product is degined with the earth tied to ov a the cabinet is metal ect... Yeah the cabinet is metal. Is that the reason why the earth wire is connected to the 0V in the panel?
jmsa7 Posted September 18, 2011 Author Posted September 18, 2011 And do your cabinets have 240v ac in them? Well some do, others have a separate cabinet with the charger and batteries.
fozzies Posted September 18, 2011 Posted September 18, 2011 Ignoring mains earth faults, you are probably looking at a short to earth somewhere. if your 0v connection gets shorted to earth at some point, you end up with a potential difference, and current will therefore flow between the short and your other earth/0v( the proper 0v). this will introduce "****" onto your cables, and interfere with it in various ways. on a data line it may make communications hard, or it may be the cable connects straight to your control electronics and just puts **** onto the whole system. either way, it has to be got rid of. act meters ( google it) sell a whole range of mains filters that can deal with earth faults, but the best option is to find and resolve the issue. a resistancw check between mains earth and your disconnected cables will show a short to earth Omg, c ra p is a blanked out word???
neil.c Posted September 19, 2011 Posted September 19, 2011 An earth fault on the field wiring is a fault between either pos or neg and the screen, it can be caused by water or poor installation practices. This fault wants to be sorted out as the power on the wiring will take the path of lowest resistance which could leave equipment in the field not working.
sjsturner Posted September 20, 2011 Posted September 20, 2011 And if your really unlucky you might get the fault that only occurs whilst theres voltage present which means you cant use your meter to find it! Always funny watching people chase faults on the buzzer setting because they dont know what ohms are.
fozzies Posted September 21, 2011 Posted September 21, 2011 Always funny watching people chase faults on the buzzer setting because they dont know what ohms are. LOL
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