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#29801 - 09/25/03 03:01 PM Electrical Abbreviations
topsparks Offline
Junior Member

Registered: 09/25/03
Posts: 3
Loc: London UK
Hi

I am studying to be an electrician and keep coming across various abbrevitions that i dont fully understand. Please could somebody explain to me what the following abbrevitions mean.

Uo
Uoc
Ib
In
Iz
It
P

also are there any books that focus on electrical calculations,abbreviations etc

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#29802 - 09/25/03 04:54 PM Re: Electrical Abbreviations
Redsy Offline
Member

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
Vo= Volts out, or output
Voc= Open circuit voltage
Ib= current in "B" phase
In= current in neutral
It= total current
P= power
Z=impedance(not sure about Iz)

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#29803 - 09/25/03 09:40 PM Re: Electrical Abbreviations
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
Iz is the current flow through an impedance.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

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#29804 - 09/26/03 01:06 AM Re: Electrical Abbreviations
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Hi there topsparks, and welcome to ECN.

I see from your profile that you're in London, which from the abbreviations you are quoting I take to be London, England and not London, Ontario.

The current references listed have specific meanings according to the British IEE, and the subscripts they use aren't particularly logical:

Ib = Design current of circuit

In = Rating of protective fuse or circuit breaker

It = Tabulated current rating of cable, i.e. the basic cable rating from the tables

Iz = Rating of cable in specific situation, i.e. after the application of correction factors for temperature, grouping, etc.

You can see some notes and worked examples relating to these at this link: http://www.tlc-direct.co.uk/Book/4.3.9.htm

The adoption of the symbol U for voltage is another of those amendments the IEE made to "harmonize" with common European standards. A subscript "o" is commonly used to refer to a nominal level, hence the use of Uo to refer to the nominal supply voltage.

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#29805 - 09/26/03 03:48 AM Re: Electrical Abbreviations
Redsy Offline
Member

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
Interesting, Paul.
Thanks for the explanation!

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#29806 - 09/26/03 05:21 AM Re: Electrical Abbreviations
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
topsparks,Welcome to ECN, mate!.
Anymore abbreviations that you are unsure of, or anything else related to electricity?.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

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#29807 - 09/26/03 10:37 AM Re: Electrical Abbreviations
topsparks Offline
Junior Member

Registered: 09/25/03
Posts: 3
Loc: London UK
hi all

thanks for the nice warm welcome, ive been reading these forums for some time and am very impressed so i thought it time to join.

pauluk you are right i am in london england .
when you say design current, is that the maximum amount of current for that circuit or the estimated current flow

Redsy Uo and Uoc are with a U and not a V, does it mean the same thing = Volts?

in a domestic installation i assume Uo would be the voltage at each socket/light etc, but with or without load?

open circuit voltage i assume to be the voltage without any load(not swithed on)but measured where?

Thanks everyone for the input, exactly what i wanted, just a few bits that i need to clear up.

cheers

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#29808 - 09/26/03 10:52 AM Re: Electrical Abbreviations
C-H Offline

Member

Registered: 09/17/02
Posts: 1508
Loc: Stockholm, Sweden
Topsparks,
 Quote:
in a domestic installation i assume Uo would be the voltage at each socket/light etc, but with or without load?


The nominal voltage is simply the voltage that you write on signs and design appliances for. In the UK it's 230V or 230/400V. It cannot be measured, but in theory it is without load on the panel (consumer unit).

 Quote:

open circuit voltage i assume to be the voltage without any load(not swithed on)but measured where?


If there is no load, there is no voltage drop and the voltage will be the same everywhere.

For some reason, U appears to be used for voltage and V for potential in Europe. The Americans use V for both, I think.


[This message has been edited by C-H (edited 09-26-2003).]

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#29809 - 09/26/03 11:02 AM Re: Electrical Abbreviations
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
V is used in North America—while some older references use E, as in E=IR.

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#29810 - 09/26/03 11:14 AM Re: Electrical Abbreviations
C-H Offline

Member

Registered: 09/17/02
Posts: 1508
Loc: Stockholm, Sweden
Here are two definitions of nominal voltage:

A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (e.g., 120/240 volts, 480Y/277 volts, 600 volts). The actual voltage at which a circuit operates can vary from the nominal within a range that permits satisfactory operation of equipment.

and

Voltage by which an installation or part of an installation is designated.

{Why is it I always have to go back and edit my posts? Why can't I write it right the first time? }

[This message has been edited by C-H (edited 09-26-2003).]

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