If I remember correctly, that is thumb rule given in American Electrician Handbook. May be it is for motor full load operation. In OP case it may not be so or the design is flawed.
you're wrong. no you're stupid. well you're stupider so there.
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Or none of the above.
Line in the sand?
Tony S
Senior Member
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I'll go with that, we ran 800HP blowers each fed from its own 800kVA transformer. They were installed in the 60's and ran until 2013 when the plant was demolished.
Shame. A lot of our process industries are going down the tube.
As in quit.
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Interesting. In US idiom drawing a line in the sand is challenging someone to agree/yield or face severe consequences.
Implies that there can be no compromise.
Oh well, he can do any or all of the above if that's what floats his boat..................
Really?
So why does it overtemp according to the OP?
You may consider that fine. I don't.
he never said that
he expected it to, but it did not
'usually', but not in this case, in this case flatlined at 840 kva
motor fl kva 845 < 875 xfmr rating
all is copacetic
"usually it just runs over temp."
is what he posted. Exactly what he posted.
Why do you continue to refute that?
because you misinterpret it
'usually' but not in this case
why not 'it ran over temp'?
the problem was not over temp
but output clamped at 840000 kva
could not get 840001 out of it
ran cool as a cucumber
wwhitney
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You guys made me go look at the original thread. The full sentence was "I've never seen it before, usually it just runs over temp." That's of the form "I've never seen X before, usually I just see Y". Which is not 100% clear, I would say that sentence alone is ambiguous about whether Y is occurring or not.
Cheers, Wayne
Cheers, Wayne
If it does so in any case it is not rated for the load. It really is that simple.
if overloaded
it ran over temp and output was limited
or
it usually runs over temp but in this case output was limited
imo it appears the xfmr is not the issue with the data we have
never saw one that flatlined below rating
usually will put out 150% but over temps unless aux cooling
load is 845 max (may be as low as 750 depending on where the 840 was measured)
xfmr 875
not an issue imo
nor does it explain the op's issue, ie, clamped output at 95% rating
Colour it any way you want. Ignore the stated facts.
Bottom line, the transformer ain't big enough. Even the OP accepts that.
the stated facts
no over temp
clamped output
the op never stated it was undersized
only that it may (he believes) be the issue due to clamped output
he also said he lacked info and never saw anything like this before
imo there is no issue, motor ran fine at 85-95% loading depending where the 840 was measured
an xfmr is not a discrete device
it is analog
it will no clamp < rating
in fact it will perform well over rating
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