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Thread: 220/230/240 Volts, Explain Please

  1. #1
    JohnnyJohnsoninWI is offline Hot Rolled
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    Hello,
    When ever the subject of 220, 230, and 240 volts (a/c) comes up, I assume they all mean the same thing (for all practical purposes). Same thing goes for the 110/115/120 and 440/460/480 voltage ratings. For instance, during a conversation with a friend, I might refer to a breaker panel as a 240 volt while he prefers to call it a 230 volt panel. We are talking about the same thing, aren't we?
    Are there times when the distinction is important? Which terminology is correct?

    Thanks,

    John

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    bnelson is offline Senior Member
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    When ever the subject of 220, 230, and 240 volts (a/c) comes up, I assume they all mean the same thing (for all practical purposes).
    Correct.

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    JohnnyJohnsoninWI is offline Hot Rolled
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    Hi BNelson,
    Thanks for your reply.
    Here's the scenario that got me thinking about this subject.
    I have a Monarch 50 series, model 1650 lathe. The tag on the control panel states 460V ac. The motor plate states 10hp, 1150-3000 rpm, winding = Exd. Shunt, 70V flange, 480V armature.
    My 3-P power is provided by a Phase Perfect DPC-A10, averaging 239V arcoss the lines. This feeds through a Hevi-Duty 20KVA drive isolation transformer. Output voltages on tap #2 average 493 volts and on tap #3 average 454 volts. Readings were taken with no load down stream.
    I chose tap #3; is this what you'd choose?

    Back to my original post. When you get up to the 440/460/480 volt range; I realize the percent difference is unchanged, but aren't the actual voltage differences becoming significant?

    Thanks again for your consideration.

    John

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    peterh5322's Avatar
    peterh5322 is offline Diamond
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    "Output voltages on tap #2 average 493 volts and on tap #3 average 454 volts. Readings were taken with no load down stream. I chose tap #3; is this what you'd choose?"

    Yes, that's what I would choose.


    "Back to my original post. When you get up to the 440/460/480 volt range; I realize the percent difference is unchanged, but aren't the actual voltage differences becoming significant?"

    Significant in several ways, some being legal ones.

    So-called "300 volt class" wiring methods and materials includes 60/120 [ *** ] , 120, 120/240, 240 [ * ] and 277 volts.

    So-called "600 volt class" wiring methods and materials includes 380, 415, 480 [ ** ] , 575 and 600 volts.

    277 is really the line-to-neutral voltage of a 480 volt Wye system, but there is an advantage to 277 volts over higher and lower voltages for the types of loads (predominately gas-discharge illumination and some single-phase dc drives) which this voltage is used for, one of these being a 277 volt branch circuit is "300 volt class".

    [ * ] Assumed to include 220, 230 and 240 volts.

    [ ** ] Assumed to include 440, 460 and 480 volts.

    [ *** ] 60/120 is permissible only for certain so-called "technical" loads, predominately professional sound reinforcing equipment, and sound recording equipment.

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    bnelson is offline Senior Member
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    When you get up to the 440/460/480 volt range; I realize the percent difference is unchanged, but aren't the actual voltage differences becoming significant?"
    Agree with Peter's comments above. Also, when it comes to running induction motors, feeding them voltages within 10% of nameplate is entirely acceptable. A 240 volt motor really does not care if it's fed 220, or vice versa.

    Voltage imbalance between the three phases, on the other hand, is much more of an issue, and can lead to windings overheating or, in extreme cases, burnout (e.g., submersible pump under heavy load).

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    <countryman> Guest

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    220/230/240 Volts/50 cycles are or were all common here in europe.
    220 Volts were standard in continental europe
    240 Volts in the UK
    230 volts are a compromise and have been introduced several years ago with the establishment of the EU.
    For motors its all the same, but light bulbs are a bit more sensitive. A 220 V bulb will burn out soon on 240 V.
    countryman/germany

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    peterh5322's Avatar
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    "230 volts are a compromise and have been introduced several years ago with the establishment of the EU."

    The word-of-art which the EU used is "harmonized".

    Although different EU memebers had previously standardized, variously, on 220, 230 or 240 volts, these being the (single-phase) line-to-neutral voltage of distribution secondary 220Y380, 230Y398 or 240Y415 (thee-phase) systems, all countries agreed to "harmonize" to 230Y398, even though 220Y380 and 240Y415 were far more common.

    For example, my former employer manufactured mainframe computers with 200 (Delta), 208 (Wye), 240 (Delta), 380 (Wye) and 415 (Wye) line input. 208 and 240 were clearly intended for North American installations, while 380 and 415 were clearly intended for European installations. 200 was intended for Japanese installations.

    We never made any 398 products.

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    Jraef's Avatar
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    Part of the confusion stems from the concept of "Distribution Voltage" and "Utilization Voltage". In the US, the common industrial Distribution Voltages are 240 and 480V. Some older systems are still 220 or 440V, but they are slowly being replaced as equipment wears out. Motors have now standardized on Utilization Voltages of 230 and 460V, partly as a compromise position between 220 / 440 and 240 / 480, but also to allow for some voltage drop on long motor leads. All in all it doesn't matter as bnelson put it earlier. Motors can easilly tolerate a wide voltage swing as long as it is relatively balanced.

    The only tricky spot is in older motors labeled for 208-230V. They are really 220V wound motors that will tolerate 200V - 240V because it is still within +-10% of 220. The problem is, they do NOT tolerate much over 240V, so if you have a 240V system that occasionally climbs another 5% to 250V, that becomes almost 15% over the 220V design rating and can be problematic. Usually you would not buy a 208V motor for a 240V system so it is rarely a problem, but it is something to watch for when buying off of eBay or somewhere like that.
    S_W_Bausch and TDegenhart like this.

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    bnelson is offline Senior Member
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    Usually you would not buy a 208V motor for a 240V system so it is rarely a problem, but it is something to watch for when buying off of eBay or somewhere like that.
    Amen to that. I do buy big motors off eBay quite often, many from MECI in Dayton, Ohio. I specifically avoid any motor rated for 208 volts, as I always buy these for making large RPCs. There are quite a few of these 208 volt motors listed on eBay, many even great makes like Baldor.

    I avoid them for just the reason you state.

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    JohnnyJohnsoninWI is offline Hot Rolled
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    Thanks for your comments everyone. I thought the voltage terminology was, or could be, used interchangably.
    Your comments about distribution vs. utilization voltage and avoiding 208V motors are very helpful. You learn something every day.

    As far as the legal significance of 480V goes, I'm curious. I used 600V rated wiring (brown, yellow, and orange colored) and a 480V breaker panel down-stream of the transformer. Are there other wiring details or techniques to consider when working at this voltage that differ from 120 or 240 wiring practices? For instance, are wire nuts allowed?

    Thanks again for your help.

    John

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    "Are there other wiring details or techniques to consider when working at this voltage that differ from 120 or 240 wiring practices? For instance, are wire nuts allowed?"

    The main difference is in the types of insulation allowed.

    For example, type SO cordage is 600 volts, whereas type SJO (J means "junior") is 300 volts.

    Most individual strands such as THHN or THWN (N means "nylon jacket") is 600 volts, whereas "Romex" (type NM or type UF) may be thermoplastic only, and could be 300 volts only.

    Anyway, for more than 277 volts ... and, indeed, for 277 volts ... I run metallic conduit and individual THHN or THWN wires.

    I can't answer the question about wire nuts as there are so many types, and I usually employ Ideal brand compression connections, the ones with the rubber "diaper" applied over the connection.

    I'm a firm believer in compression connections, particularly those made using an approved "closed cycle" (fool-proof, ratcheting type) mechanism.

  12. #12
    JohnnyJohnsoninWI is offline Hot Rolled
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    I've seen those connections with the rubber diaper, but didn't know what they were called. I'll give them a try; I'm always looking for a better way.
    All my machinery wiring is with THHN through emt.

    Thanks,

    John

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    CBA
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    The actual voltage in the UK is still 240, and in continental Europe 220. In my guess it will take a generation or two, until 230V will be the standard in all of Europe.

    In the meantime, there is already an advantage from the EC compromise. In the past, a French 220V motor did overheat if used in the UK. A UK 240V motor did not bring full power and efficiency if used in Germany. Now, all motors in the EU can be manufactured for 230V and sold anywhere in Europe. They will work fine on 220 or 240V regardless, cause the difference to the rated 230 is less than 5%. In theory, the motors should be slightly more expensive to make, cause they need to be rated to deliver nominal power at 220V, yet the temperature rise must cope with the 240V. In practice, having to make and stock motors for one only voltage more than compensates for this. Chris

    Quote:
    220/230/240 Volts/50 cycles are or were all common here in europe.
    220 Volts were standard in continental europe
    240 Volts in the UK
    230 volts are a compromise and have been introduced several years ago with the establishment of the EU.
    For motors its all the same...
    Unquote

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    peterh5322's Avatar
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    Europe apparently makes motors which are rated for single voltage use only, and perform properly and fully only if operated at rated voltage.

    Here in the U.S., we have motors which are rated for, and will perform properly and fully on 208-240 volts. (208-240/440-480 motors are also quite common).

    Rated current is significantly higher on 208 than on 240, which is common sense as this is not a resistive load, but is an inductive load.

    Having had the coils wound for the higher current expected for 208 operation allows the motor to perform fully, and at significantly less current on 240.

    Of course, if the motor is rated for 240 only, then the wire size will be smaller, and operation on 208 will result in higher heating losses, and, therefore overheating. Obviously, rated power cannot be delivered under this circumstance.

  15. #15
    <countryman> Guest

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    "he actual voltage in the UK is still 240, and in continental Europe 220. In my guess it will take a generation or two, until 230V will be the standard in all of Europe."
    No, the alteration is already effective. Measured Voltage in my house in germany at the moment is 233-235Volt

    When the change from 220 to 230 volt was up-to-date it was published that implements such as refrigerators, motors and the like would not be affected as they were tolerating +-10% in voltage easily. Only light bulbs were a problem, as their lifetime is shortened by each extra volt.

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    CBA
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    No, the alteration is already effective. Measured Voltage in my house in germany at the moment is 233-235Volt

    It would really surprize me in the short time - such alteration would cost billions. The 233/235 you measured are still well within the tolerances of your former 220V standard, +10/-15% if I remember well. You may observe your voltage over several days, at different times of the day, to get a feel for variation and average. From a colleague in northern UK, I heard that they still have 240V, and it can still rise to 260 at times.
    Chris


    When the change from 220 to 230 volt was up-to-date it was published that implements such as refrigerators, motors and the like would not be affected as they were tolerating +-10% in voltage easily. Only light bulbs were a problem, as their lifetime is shortened by each extra volt.
    --------------------------------------------------------------------------------

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    Trick1 is offline Junior Member
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    Hello Board,
    I thought it went by the breaker size on a double pole ie:
    (20amp = 220) - (30amp = 230)- (40amp = 240)?

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    bnelson is offline Senior Member
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    I thought it went by the breaker size on a double pole ie:
    (20amp = 220) - (30amp = 230)- (40amp = 240)?
    This thread is discussing volts, not amps.

    However, the coding system Square D uses for some of its breakers is as you say; for example, a 'QOB340' is a QO type bolt-on three pole 40 amp breaker.

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    S_W_Bausch is offline Diamond
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    Quote Originally Posted by Jraef View Post
    Part of the confusion stems from the concept of "Distribution Voltage" and "Utilization Voltage". In the US, the common industrial Distribution Voltages are 240 and 480V. Some older systems are still 220 or 440V, but they are slowly being replaced as equipment wears out. Motors have now standardized on Utilization Voltages of 230 and 460V, partly as a compromise position between 220 / 440 and 240 / 480, but also to allow for some voltage drop on long motor leads. All in all it doesn't matter as bnelson put it earlier. Motors can easilly tolerate a wide voltage swing as long as it is relatively balanced.

    The only tricky spot is in older motors labeled for 208-230V. They are really 220V wound motors that will tolerate 200V - 240V because it is still within +-10% of 220. The problem is, they do NOT tolerate much over 240V, so if you have a 240V system that occasionally climbs another 5% to 250V, that becomes almost 15% over the 220V design rating and can be problematic. Usually you would not buy a 208V motor for a 240V system so it is rarely a problem, but it is something to watch for when buying off of eBay or somewhere like that.
    Yes, I dredged up an old thread For those situations where a "208 - 220 volts" motor is running on 240 volts, and there is concern regarding overvoltage, would a properly set-up VFD mitigate the issue?

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    Rob F. is offline Stainless
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    Quote Originally Posted by S_W_Bausch View Post
    Yes, I dredged up an old thread For those situations where a "208 - 220 volts" motor is running on 240 volts, and there is concern regarding overvoltage, would a properly set-up VFD mitigate the issue?
    Quote Originally Posted by peterh5322 View Post
    Rated current is significantly higher on 208 than on 240, which is common sense as this is not a resistive load, but is an inductive load.

    Having had the coils wound for the higher current expected for 208 operation allows the motor to perform fully, and at significantly less current on 240.

    Of course, if the motor is rated for 240 only, then the wire size will be smaller, and operation on 208 will result in higher heating losses, and, therefore overheating. Obviously, rated power cannot be delivered under this circumstance.
    I was curious about this also and am reading the 208-240 motor is more desirable than a 220-240 motor? Less chance of overheating on 240V if I am understanding correctly.
    Rob

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