Power mains 220VAC 20A on terminals???


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    Default Power mains 220VAC 20A on terminals???

    I'm trying to find some comfort in how Tormach designed the electrical power transmission within the 1100. First thing is 1-1/2hp even possible on 220v@20a, maybe, but you have the mains coming in to spring load terminal strips! I will say that the springs do have some tension on them, however with just a little resistance heat buildup from the current those springs will lose then compressive strength & only add to a higher impedance.

    Has anyone had any power issues? Maybe something like components power cycling when the machine is under a heavy load? or losing steps when all axes are moving with spindle running?

    I'm not sure where the power is distributed from the secondary 110v input but I assume it's isolated.

    I was thinking about spreading the 220 electrical over 2 or more terminals instead of the single terminal currently used, or dedicate a terminal for the 3 phase converter & another terminal for the rest of the circuitry.

    Wormwood

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    Default Re: Power mains 220VAC 20A on terminals???

    220v * 20A = 4400 watts

    4400 watts / 746 watts/hp = 5.89 hp

    Sent from my Z958 using Tapatalk



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    Default Re: Power mains 220VAC 20A on terminals???

    20A at 220 is more than enough for 1 1/2 hp.... true 1 1/2 (not the "compressor rated" or "peak hp" nonsense) should be around 7-7.5A or so if the motor and conversion to 3 phase are reasonably efficient. My 5 hp compressor motor is 85% efficient, and goes about 4.4A/hp on 220.

    To answer the question, though: no, never had power issues or problems like those listed.

    Ultimately, I think the real answer is that the 1100 is a decade old design; if there was a major flaw of the sort imagined, it would be well known by now.



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    Default Re: Power mains 220VAC 20A on terminals???

    Quote Originally Posted by 109jb View Post
    220v * 20A = 4400 watts

    4400 watts / 746 watts/hp = 5.89 hp

    Sent from my Z958 using Tapatalk

    I knew when I was typing that question, someone was going to give a formula....


    Let me ask this another way, is it possible to reliably squeeze 220vac 20 amps thru the spring terminals? For example the NEMA plug & socket I use has brass screw terminals contact plates for the wires, similar to the breaker at the electrical panel. So why even bother making nema plugs & sockets with such a robust electrical connections if a spring terminal would suffice? I just can't see enough contact surface at that junction that could handle 10amps each. It seems like they'd get hot & weak over time???



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    Default Re: Power mains 220VAC 20A on terminals???

    Quote Originally Posted by GLCarlson View Post
    20A at 220 is more than enough for 1 1/2 hp.... true 1 1/2 (not the "compressor rated" or "peak hp" nonsense) should be around 7-7.5A or so if the motor and conversion to 3 phase are reasonably efficient. My 5 hp compressor motor is 85% efficient, and goes about 4.4A/hp on 220.

    To answer the question, though: no, never had power issues or problems like those listed.

    Ultimately, I think the real answer is that the 1100 is a decade old design; if there was a major flaw of the sort imagined, it would be well known by now.

    Thank you, and that's what I hoping to hear... now I just need to find another use for the SOOW wire I had bought...

    Wormwood



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    Default Re: Power mains 220VAC 20A on terminals???

    We use Spring Grip WAGO Terminal Blocks in the Railway business for just the reason that you question.

    They are MUCH LESS prone to heating than screw down terminals. The spring terminals maintain a uniform loading on the connection compensating for expansion, contraction and mechanical loads. Screw down terminals tend to squeeze the wire with expansion and contraction potentially causing the wire to loosen increasing the resistance slightly, leading to terminal heating which causes oxidation increasing the resistance leading to higher heating and and and - you get the idea.

    Spring clips can be superior to screw down terminals BUT like any apparatus the ampacity rating must be observed and respected.

    Additionally 20A is the rated service size and set to protect the wire not limit the current draw of the machine, current draw of the machine will rarely if ever approach this amount.

    I agree with GLCarlson, the design and construction of the 1100 is very mature, mine is pushing 6 years of serious work. If this was a weakness it would have surfaced by now. Biggest issue that I am aware of along these lines in overheating of the stepper motor leads at the drive. There have been several cases of overheating and burning of the connector presumably from loose terminal screws.

    gary



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    Default Re: Power mains 220VAC 20A on terminals???

    Quote Originally Posted by wormwood View Post
    First thing is 1-1/2hp even possible on 220v@20a, maybe, but you have the mains coming in to spring load terminal strips! I'm not sure where the power is distributed from the secondary 110v input but I assume it's isolated.
    Note that 1 mechanical HP is equivalent to about 745.7 Watts (often rounded to 750 Watts), and also 220VAC has not been a US standard line voltage for decades. The nominal voltage level for that within the US is 240VAC. Likewise 110VAC is no longer a US standard, 120VAC has been the US standard house voltage for decades.
    https://en.wikipedia.org/wiki/Mains_electricity

    240VAC * 20A = 4.8KW, when the current and voltage are exactly in phase. With an inductive run motor the current and voltage will not be exactly in phase but you can still get several HP out of a 240VAC @ 20A socket. It is also worth noting that a 20A socket and breaker are only rated at that current for short periods of time, the continuous current rating is always 80% of the nominal rating. Hence the real long term ratings are 240VAC @16A, which is 3.84KW, or slightly over 5HP continuous.



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    Default Re: Power mains 220VAC 20A on terminals???

    Quote Originally Posted by nitewatchman View Post
    We use Spring Grip WAGO Terminal Blocks in the Railway business for just the reason that you question.

    They are MUCH LESS prone to heating than screw down terminals. The spring terminals maintain a uniform loading on the connection compensating for expansion, contraction and mechanical loads. Screw down terminals tend to squeeze the wire with expansion and contraction potentially causing the wire to loosen increasing the resistance slightly, leading to terminal heating which causes oxidation increasing the resistance leading to higher heating and and and - you get the idea.

    Spring clips can be superior to screw down terminals BUT like any apparatus the ampacity rating must be observed and respected.

    Additionally 20A is the rated service size and set to protect the wire not limit the current draw of the machine, current draw of the machine will rarely if ever approach this amount.

    I agree with GLCarlson, the design and construction of the 1100 is very mature, mine is pushing 6 years of serious work. If this was a weakness it would have surfaced by now. Biggest issue that I am aware of along these lines in overheating of the stepper motor leads at the drive. There have been several cases of overheating and burning of the connector presumably from loose terminal screws.

    gary

    I think that says it all, 'it's a mature design...' if there was any potential for failure we would have seen something by now. Thx!

    Wormwood



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    Default Re: Power mains 220VAC 20A on terminals???

    Quote Originally Posted by Zetopan View Post
    ...It is also worth noting that a 20A socket and breaker are only rated at that current for short periods of time, the continuous current rating is always 80% of the nominal rating...
    Not entirely true. I've spent a fair amount of time specifying electrical components for various products over the years. A 20A breaker is rated to carry 20 amps continuously however electrical code and/or device standards (such as UL) dictate that the wire and breaker rating be over sized by some amount (125% for resistive loads, up to 300% for inductive loads).

    This guy gives a good explanation of how breakers function with the curve provided by Square D. Not as simple as I once thought.
    https://diy.stackexchange.com/questi...-blow-breakers



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    Default Re: Power mains 220VAC 20A on terminals???

    Quote Originally Posted by IMT View Post
    Not entirely true. I've spent a fair amount of time specifying electrical components for various products over the years. A 20A breaker is rated to carry 20 amps continuously however electrical code and/or device standards (such as UL) dictate that the wire and breaker rating be over sized by some amount (125% for resistive loads, up to 300% for inductive loads).
    Your statements are essentially correct, and I should have included more details. While the circuit breakers are actually rated to continuously carry 100% of their rated current, the differences in the circuit breaker housing (i.e. the complete electrical panel) and wiring means that you must take into account other sources of heat caused by the additional circuits and variations that an isolated breaker would never see. The actual circuit breaker ratings are in a free air environment (not confined in an enclosure) with an ambient temperature of 40 degree C, and no other heat sources are present. As a result the US National Electrical Code "NEC Sec. 384-16 (c)" specifies that the continuous electrical load should never exceed 80% of the breaker rating, to allow for an enclosed breaker environment and additional heat sources, etc. Hence a 50A 240VAC circuit breaker is, according to NEC Sec. 384-16 (c), only allowed to handle a continuous load current of 40 Amps (80% of 50 Amps). And likewise a 15A 120VAC breaker is only allowed to handle a continuous current of 12A (80% of 15A). That is what I was previously addressing it a way too terse manner. Anyone rewiring their house or shop 120VAC or 240VAC had better pay attention to the 80% ratings or your insurance will *not* cover any related resulting electrical fire since it clearly violates the NEC requirements.



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Power mains 220VAC 20A on terminals???

Power mains 220VAC 20A on terminals???