Component Names

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Old 03-31-14, 12:15 AM
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Component Names

In the UK we seem to be having a problem with what items are called I wonder if the same is true in USA?

Examples.
Transformer we traditionally considered as being a wire wound device to step up or down or isolate. Today we are finding inverters being called transformers and when advising people if they can fit LED lights to extra low voltage systems it becomes hard to explain what step down lumps will and will not allow use of LED.

Low Voltage we define this as AC between 100 - 1000 volts but we get a lot of extra low voltage stuff marked as low voltage.

Ballast we consider this as a special choke to run a florescent tube from again wire wound seeing now inverters and switch mode power supplies also called ballast.

Live and Line also getting mixed up. We earth one of the supply wires as the supply transformer and we call that wire neutral will also have the phase wires and with single phase we call it line. Both line and neutral are both called live. However finding a lot of equipment with the Line wire called Live.

Our 110 volt is either 55-0-55 or 63-0-63 depending if from single or three phase source. With this split phase supply we should have Line 1 and Line 2 and colours should be Brown - Black or Grey - Green/Yellow but when we open any appliance we find Brown - Blue - Green/Yellow and terminals marked L and N not L1 and L2.

Although in USA you use a sort of English you I know use different words and with electrics also have different words like our earth = your ground not sure what you call bonding?

So question is are you also having a problem with descriptions? With some areas like welding we have transformer or inverter the latter being a HF unit but with lighting we are lucky is some one includes the word electronic at least you have a good idea what it is if called an electronic transformer but not what I would call it.

Thanks Eric
 
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  #2  
Old 03-31-14, 05:32 AM
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A "transformer" proper is the component with one coil (the primary) for the source current and another coil (the secondary) for the output current of a desired different voltage.

An "inverter" converts direct current to alternating current. The inverter unit (box) may or may not contain a transformer depending on the voltage of the output desired.

A "power pack" for a model train converts AC to DC. It almost always contains a transformer to step down the voltage and it also contains rectifiers to do the actual AC to DC conversion. (There are other, alternative, components such as choppers that will also step down the voltage.)

A "ballast" limits current (amperes) as the resistance of the lamp or other application decreases notably during warmup. The ballast's makeup varies depending on the application. For a mercury vapor lamp or a fluorescent lamp, a simple coil will do the trick. For sodium vapor lamps, some electronic circuitry is needed also. All of the so-called vapor lamps (which includes all fluorescent lamps) need the ballast so the final current settles down to the current the lamp wants. Without a ballast the natural course of events will have the current increase as infinitum and the lamp will self destruct.

"Bonding" in a general sense means the making of an essentially resistance free connection between wires and/or metal objects in the sense that if A is bonded to B and B is bonded to C then A is bonded to C. The context may vary, for example for bonding in building grounding systems, heavy wire such as #6 or #4 is needed while for electronic equipment a #22 wire may suffice. Some electricians use the term bonding only when bonding to a grounding system. The actual contact between an element of a grounding system and earth is not considered a bond (it is not exactly resistance free).

"Electronic" refers to equipment containing a number of semiconductors (or vacuum tubes), capacitors, resistors and coils. A device containing just one or two of those items is generally not called "electronic."

I would be worried about shorter appliance life if I have 110 volt appliances running off of a 63-0-63 supply used as a 126 volt supply. For proper operation the appliances would need to be designed with a tolerance much greater than plus/minus 10% or be really designed for 120 volts that is the U.S. standard. Incandescent lamps rated for 110 volts will have a noticeably shorter life on 126 volts.

The labels L1, N, etc. are also seen in U.S. appliances. Nowadays the frame should not be bonded to any of those terminals including the N so if the two hot lines of a 55-0-55 supply were connected to L1 and N expecting 110 volts (there being no L2) then everything should work normally. There are older U.S. appliances where N and the frame are bonded but they possess both L1 and L2 intended for the hot legs of a 240 volt (12-0-120) supply. The remaining supply wire is grounded (is the neutral) and safe to connect to the N terminal assuming no defects in the building electrical system.

"Live" means capable of sustaining a meaningful current between it and some other object or between it and the earth or a grounding system. If the neutral between a device (a load) and the power source is broken, the downstream broken end will be live since the moment you touch that end to the grounding system, current will resume flowing from the source via the hot wire, through the load, and through the neutral from the load to where you touched it to the grounding system. Live can be relative. A wire is said to not be live when it is supplied by a switch that is turned off but it is possible that due to the juxtaposition of that wire with other wires that are live, there can be induced voltages large enough to produce a lethal current flow if the "dead" wire is touched.

Transformers isolate the circuitry connected to their output (secondary) from the supply unless specifically wired to not isolate. Isolated means neither output terminal is live relative to the house ground although each output terminal is live relative to the other Actually there are transformers whose output voltage is the same as the input voltage and whose purpose is to isolate some circuitry.

"Line" refers to one of the supply wires coming from the power source, or one of the terminals on the load device where you connect such a wire. A ground fault circuit interrupter has "line" terminals where you connect the supply wires and "load" terminals where you connect wires going to additional loads (downstream). You may connect both sets of wires to the line terminals for the purpose of having the additional loads not subject to (not protected by) that GFCI unit.

In the U.S. "low voltage" generally refers to circuits or power supplies involving less than 40 volts.

Inside an appliance, wire colors may or may not adhere to standards. In the U.S. building wiring is supposed to use green for earthing, white or light gray for neutral (grounded current carrying conductors), and other colors for ungrounded live conductors. Informally, orange is used for the phase of certain 3 phase systems not intended to be used together with a neutral as its voltage to neutral is different from the phase to neutral supply (such as 120 volts) provided for single phase loads.

In the U.S. a variety of terms including "low", "medium", "high", "very high", "ultra high" etc. are used to describe frequency bands (for radio etc. broadcasting and also including alternating current). It so happens that "medium frequency" stands for about one megahertz or "ten to the power six" aka 10^6 Hz. More exactly it is the range 10^(5-1/2) to 10^(6-1/2) or 10^5 times the square root of 10 up to 10^6 times SQRT(10) or about 316 kilohertz to 3.16 megahertz. (The next band, high frequency, is 10^(6-1/2) to 10^(7-1/2) Hz.) Using this scale, 50 Hz and 60 Hz current are referred to as super low frequency.

Now, one to rib you folks from the U.K. A "trolley" is a small device or assembly that runs along a suspended or overhead wire or rail; the term was first used to refer to such a device used as an electrical contact. "Trolley" may also refer to something such as a streetcar that possesses or uses such a device in the sense that some airplanes are referred to as just "jets" and some ovens are referred to as just "microwaves." I suppose that using this same grammatical sense, "transformer" is used to refer to a more elaborate device containing or supposedly containing a transformer.
 

Last edited by AllanJ; 03-31-14 at 08:06 AM.
  #3  
Old 03-31-14, 06:09 AM
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Like Professor Higgin's said..."English? the Americans haven't used in years."
 
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Old 03-31-14, 07:38 AM
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Informally, orange is used for the phase of certain 3 phase systems not intended to be used together with a neutral as its voltage to neutral is different from the phase to neutral supply (such as 120 volts) provided for single phase loads.
In the U.S., orange is used, formally, as the indicator for the "B" phase live conductors in a 3-phase 277/480V service. The three "high voltage" colors - brown, orange and yellow, started out to be yellow shifts from the three "low voltage" (120/240V) colors - black, red and blue. Since adding yellow to blue produces green, in pigments, the third 277V color became yellow by itself, without the blue, because green was already dedicated to indicate a grounding conductor.
 
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Old 04-01-14, 04:38 AM
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Thank you AllanJ what a great list so things do seem to be asking for problems when I see what things as called in USA when compared to Europe (Our regulations in UK are harmonised with Europe, although we do have a few extras so in general UK electrics as safer than other European countries.). There are some very worrying differences and after your post I can see how dangerous this could be with items being supplied across the pond between USA and Europe.

Line taken from our regulations:- Line conductor. A conductor of an a.c. system for the transmission of electrical energy other than a neutral conductor, a protective conductor or a PEN conductor. The term also means the equivalent conductor of a d.c.
system unless otherwise specified in the Regulations.

The word Line and Live seem to have swapped what you call live we call line. (PEN conductors are not allowed in the home only on the supply network and it refers to one wire being both neutral and earth.)

Low Voltage again from our regulations:-
Voltage bands
Band I
Band I covers:
- installations where protection against electric shock is provided under certain conditions by the value of voltage:
- installations where the voltage is limited for operational reasons (e.g. telecommunications, signalling, bell, control and alarm installations).
Extra-low voltage (ELV) Will normally fall within voltage Band I.
Band II
Band II contains the voltages for supplies to household and most commercial and industrial installations.
Low voltage (LV) will normally fall within voltage Band II.
NOTE: Band II voltages do not exceed 1000 V a.c. rms or 1500 V d.c.
Voltage, nominal. Voltage by which an installation (or part of an installation) is designated. The following ranges of nominal voltage (rms values for a.c.) are defined:
- Extra-low. Not exceeding 50 V a.c. or 120 V ripple-free d.c., whether between conductors or to Earth.
- Low. Exceeding extra-low voltage but not exceeding 1000 V a.c. or 1500 V d.c. between conductors, or 600 V a.c. or 900 V d.c. between conductors and Earth.
- High. Normally exceeding low - voltage.
Reduced low voltage system. A system in which the nominal line to line voltage does not exceed 110 volts and the nominal line to Earth voltage does not exceed 63.5 volts.

This explains why we get incorrectly labelled stuff in the main 12 volt quartz halogen lamps labelled as low voltage rather than extra low voltage.

We oddly did have one item which used the word “trolley” like you describe. The Trolley Bus was very like a tram but on rubber tires and both live feeds came from overhead wires where with a tram only one live feed comes from the overhead the other being the rail. We have also warped the language a little a tram is a single unit running on rails and a train is multi connected units running on rails however because of historic use we now call vehicle which runs on rails laid in the road a tram even if articulated and a single vehicle running on rails which do not share the road a train. There are exceptions the Welsh Highland Railway shares a bridge with the road traffic but is called a train. However traffic lights stop cars while the train is on the bridge. We have brought back trams in some cities but they don’t use the road like they did. More like Hong Kong’s light transit railway so the name tram and train seem to now be a little grey working out which is which.

Frequency with radio is now really left to the hams we still have SW, LW, and MW but most modern bands are named by their use rather than frequency so FM, DAB, Freeview (Terrestrial TV), Satellite (Free to air, Freesat, and Sky). Our mains is 50Hz which always amuses me as the longer the distance the power lines go the lower the frequency required to reduce losses so since USA is a much larger area than UK the UK frequency should be higher not lower than yours. When to send or receive power to France it is done with DC not AC. Whole of UK is synchronised not sure about rest of Europe or Ulster I know Ulster HV is 10kV where rest of UK is 11kV so don’t think Ulster is linked to rest of UK.

I was rather interested to see how you use delta supplies in UK all factories and homes are from a star wound transformer. In remote areas we do have 3.3kV and 11kV supplies to poles near to farms and houses but any more than 10 houses then all HV supplies are under ground and we use around 500kVA transformers housed normally in little brick buildings supplying a whole street of houses every third house will be on same phase. With farms and outlaying houses often a split phase rather than three phase transformer.

Fire is less of a problem for us because of the higher voltage but electric shock of can kill easier than with 120 volt so from 2008 nearly all circuits need RCD (GFCI) protection at 30ma max time 40ms this has caused a problem as most circuits only the line is switched and so earth – neutral faults are still present the domestic RCBO which is current and earth leakage combined also only switch the line the neutral is still connected because of the design of our Consumer Unit which is a type tested distribution unit for the home we can’t fit twin pole devices. There are twin pole distribution units made but these have not been type tested so can’t be used in the home.
 
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Old 04-01-14, 05:59 AM
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In the first half of the 20'th century, the U.S. had many AC power systems with 25 Hz power. Lower frequencies require transformers with larger and heavier iron cores.

Most urban and suburban on street distribution (called the primary lines in the U.S.) leaves the substation as 3 phase circuits, nowadays from 11,000 to 14,000 volts phase to phase (about 6,300 to 8,100 volts phase to ground). I have seen the phase to phase voltages 12.5 KV, 13.2 KV and 13.8 KV. Higher primary voltages (distribution voltages) perhaps up to 50,000 phase to ground may be used in rural areas. Typically just one of the phase wires goes down small side streets to serve the pole transformers that deliver the split phase 120-0-120 (we call it 120/240) volt current (secondary lines) for ten or so homes per transformer. Voltages above 50,000 are referred to as transmission line voltages and are used for lines leaving the power generating plants or running between cities or between substations.

The U.S. uses, among other voltages, 120/208 volt 3 phase star, 240 volt only delta, and 120/240 volt delta on secondary lines serving not so large customers. The 120/240 delta uses two of the 3 legs with a grounded center tap on that winding of the transformer to serve the 120 volt loads and the the third leg is used only for 240 volt loads. A common heavy load 3 phase supply such as for a factory provides 277/480 volts. I am not sure of the exact voltage bands and classifications but wire and small electrical devices such as light fixtures and receptacles might be rated for "up to 125 volts" or "up to 250 volts" or "up to 600 volts."

The usefulness of the star 3 phase system is that 4 conductors (including the center neutral) carry the same load as the 6 conductors of three independent single phase systems, and also dual voltage (e.g. 120 and 208 volts) is available

The original usefulness of the delta 3 phase system is that it needs just 3 conductors (no neutral) compared with 6 conductors for comparable single phase systems when all loads use the same voltage, for example 220 to 240 volts. Optionally, one of the three phase lines may be grounded

Almost all of the U.S. and Canada electrical systems are interconnected so that power plants can be switched in and out depending on demand and the remaining power plants serve everyone. We refer to the entire system as "the grid". As a result, the entire country is synchronized also. It's advantageous to switch off the gas or coal consuming plants when there is less demand allowing the hydro plants, where the falling water is there whether you need it or not, are on line full time. The grid system allows, say, a region with a hydro plant to receive additional power during the day from a region, say, with a large nuclear plant, and deliver surplus power via the same lines to that other region at night when the nuclear plant is turned down low.

The U.S. has no standard or commonly used devices to protect against earth-neutral faults or earth current flow other than the regulations for installing related components and systems such as grounding electrode systems. Proper installation of earthing wires (bonding jumpers, equipment grounding conductors, grounding electrode conductors) protects against hot to grounded object faults by drawing enough current to trip the breaker of the applicable branch circuit. Open neutrals, whether between the receptacle and breaker panel or between the house and the utility pole, can cause severe problems and it is up to the consumer or user to detect these problems and take corrective action.

For underground wiring in the U.S., transformers providing the 120/240 or whatever secondary voltage to multiple buildings are typically installed in above ground metal cabinets or in below ground concrete boxes (called vaults) with a grate or a manhole cover as an access.

The U.S. also has electric trolley buses, although nowadays only in about five cities.
 

Last edited by AllanJ; 04-01-14 at 07:46 AM.
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Old 04-01-14, 05:47 PM
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Again thank you for such a detailed account. Our electric system is clearly not perfect we have a supply system called PME or TN-C-S where same wire is used for earth and neutral this on the odd time causes problems normally due to road works where some one has damaged the cable. But it is rare.

One big problem is on building sites we are required to use a 110 volt (55-0-55) supply I have found USA equipment being used and switching has to be double pole always worry about any equipment being single pole switching. But although now neutral is always blue in the past it was black so when most see black and white wires they assume the black is neutral which is of course wrong.

I did work on a 110 supply in Algeria and assumed it was same as USA with 192 volt phase to phase seems from what you say that is not the case. I remember a heated argument with another electrician when I requested an auto transformer to run the AC as it was designed for 220 not 192 and was stalling on start and burning out the start gear. I could not get him to understand with three phase system 110 phase to neutral did not give 220 between phases.

I also worked on a Robin tunnel boring machine with a delta secondary 220 phase to phase that was really hard to get use to. Floating earth. Think that came from USA. Power to site was 11kV stepped down to 10kV to feed TBM where it was further reduced to 660V for main motors and 220 for lighting and control circuits. I assumed 660V was a USA standard? Our norm is 400 volt phase to phase but mines and quarries often run at 480 volt not a clue why.
 
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Old 04-02-14, 05:57 AM
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Almost all distribution systems in the U.S. use the same wire for distribution (primary) neutral, 120/240 etc. volt (secondary) neutral, and earth and that is usually hung about 2/3 up the utility pole. U.S. systems also have earthing wires going down the poles to earthing rods, at most if not all poles. Single phase (the most common) pole transformers may be connected to one phase and neutral (examples: 2,400 volts or 7,620 volts) or connected to two of the three phases (examples: 4,160 volts or 13,200 volts). Starting at the first master disconnecting switch or breaker after the meter, neutral and earthing wires are supposed to run separately in the building.

In a small number of (primary rural) areas in the U.S. there is only one wire on the utility poles and the earth/ground/soil/dirt below serves as the return to the substation! This is called SWER or single wire earth return. You can think of it as an intentional fault to earth. This works when the number of amperes in the (usually upwards of 10,000 volts to ground) distribution circuit is quite small and the ground is not too dry. But the earth is not that great a conductor and, if there is growth in demand, there will be voltage drop necessitating adding a neutral wire or installing voltage regulators here and there along the line. Neutral still accompanies the (secondary) line wires from pole transformers to buildings.

The voltage rating for an appliance implies single phase or three phase requirements. Notably 120/208 volt appliances use both voltages and must be fed with 120/208 volt or 110/192* volt star 3 phase systems and not a 110/220 volt system even if not all three phases are used. Likewise, 120/240 volt single phase appliances may not be run on 120/208 (3 phase) volt power unless also rated for the latter. Single phase appliances with just one voltage rating, for example 240 volts only may be fed with either a single phase supply or two legs of a 3 phase supply subject only to having the proper voltage. Usually a power supply up to 10% low or high in actual* voltage will work acceptably but the user has to be aware of struggling or other abnormal operation and disconnect the appliance or reduce its physical loading if that occurs.

A 110 to 120* volt tool or appliance or light should work fine on the 110 volts of a 55-0-55 system although double breakers or paired fuses are needed at the panel to control both hot legs. Double pole wall switches are recommended. In the U.S. there are 240 volt electric resistance heaters wired up to 120-0-120 systems where double pole switches (or wall thermostats) are recommended but not all cities require them. Sometimes a 2 pole wall thermostat is used to control one leg of each of two circuits feeding two heaters.

* The significance of 120/240 volts or 120/208 volts as being U.S. standards is that tolerances and fluctuations need to be taken into account. A 120/208 system can fluctuate normally down to 110/192. But if a 110/192 system fluctuates normally down to say 103/178, that is outside the expected 10% tolerance of a typical 120/208 volt appliance. Some appliances can withstand that, others can't. These situations need to be considered on a case by case basis. A dual voltage (e.g. 120/240) 3 phase system where the smaller voltage is half of the larger voltage accepts only single phase appliances using the two legs nearest the neutral if the neutral and lower voltage are utilized by the appliance.

Six hundred volts is a "dividing line" in the U.S. where circuits using less than that voltage use one set of codes while over that use other sets of codes. I don't know of any U.S. systems using 660 volts. Also almost all U.S. subway and trolley systems have used 550 to 600 volts up to about 1970, after that some systems have been built with or switched to 700 to 750 volts.

When the body of the tool is connected to (bonded to) a properly constructed earthing system (grounding electrode system) using another wire (equipment grounding conductor) in its power cord and with properly installed equipment grounding conductors in the feeds back to the panel. then floating earth should not be a problem.

Hmmmm. I'm not sure whether "mains" refers to the lines coming in from the utility pole and terminating in the panel (load center), or also refers to all of the power lines in the house from the panel to the receptacles (wall plugs).
 

Last edited by AllanJ; 04-02-14 at 07:09 AM.
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