[Info-vax] OT: the Daily WTF for today is a VAX/VMS story

[Johnny Billquist]

On 2016-02-15 00:16, Scott Dorsey wrote:
> Jan-Erik Soderholm  <jan-erik.soderholm at telia.com> wrote:
>>
>> The wood work machinery in my grandfathes shipyard had 3-phase AC
>> motors. It took several minutes to rev up some of them to speed.
>> You put the switch first to the "Y" position and when the speed
>> of the machinery was stable switched to "D". Seems to be called
>> "star-delta (YΔ) starting" in English...
>
> Yes.   That is how conventional induction motors spin up.  You'll
> notice they pull a lot of current and get pretty hot until they come
> up to speed and lock to the line.
>
>> So I do not understand this:
>>
>>> 3 phase AC motors always follows the phases of the supply like
>>> slaves. There is no spinup time. You go from standstill to full
>>> speed immediately, always.
>
> It is not true, no.

Obviously I know too little of AC motors, and have only "properly" 
played with synchronous ones, which is what I'm thinking.

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
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