On 09/08/2022 00:35, Cydrome Leader wrote:
David Billington <djb@invalid.com> wrote:
On 07/08/2022 20:17, Cydrome Leader wrote:
Motors all seem to follow NEMA sizes and standards in North America. What are the standards outside the US? Do chinese and
italian machinery use standardized motor mounts and sizes? It seems foreign industrial motors are usually rated in kW and not
horsepower, but I've also never seen clearly marked motor frame sizes on danish machinery like on all motors here. I want to know
how that all works.
AFAIK modern motors conform to the IEC metric motor standards and while
rated in kW are frequently in sizes recognisable as hp ie 0.75kW = 1hp,
2.2kW = 3hp etc. That said I have run across some modern motors with non
standard features such as smaller than standard key which I could deal
with when the motor was replaced by broaching the fan to the standard
key size.
Is it like this:
https://www.beatson.co.uk/electric-motors/standard-iec-metric-motors/#:~:text=Standard%20IEC%20Metric%20Motors%20%20%20%20kW,%20%20D90L%2A%20%2019%20more%20rows%20
Do people walk into a supply house and say something like "I need a 1kW D80 in 2800 RPM" or something like that and the rest is
magic?
In the US, a super common motor type is "frame 56", you'd still have to specify voltage, number of phases, how it starts, how
sealed up it is, and if mounts on a foot or flange at the shaft. It takes some effort to find a replacement, but they're
mechanically interchangeable enough where brand doesn't really matter. There's tons if chinese imports made to the same specs
too.
No just the same as in the US, you need to know 1ph or 3ph, number of
poles, if 1ph what starting/running system is used, mounting type etc.
If your lucky and it's a motor to the IEC standards you should be able
to get another make of motor that fits in place with the same mountings.
Some foot mounted motors have removable feet which can be moved around
to orient the connection box as required on top or either side, I don't
know if the connection box orientation is part of the standard. It's
like in the US you're just picking from a different standard, motors are
also made to the older standard but not as common.
The woodworking dust extraction fan that failed had the odd key size and
the flange details were to standard except it lacked the location ring,
shaft size and length were standard, the guy was going to grind the
location ring off the replacement motor but I said it would invalidate
the warranty so he had his assistant cut a hole in the mounting plate to
accept the location ring and all is still good.
Tons of applications use goofy length shafts or just to try to lock you in to paying too much for OEM parts, but there's nearly
always an equivalent somebody else sells.
Yes, I just had a 1ph 4hp (3kW) motor picked up this afternoon that was
a 90L frame and all the replacements I could find were 100L and I don't
know if they would fit the table saw, the motor was a special for the
table saw maker so they had a monopoly, fortunately I got it working. It
was a braked motor and the brake rectifier had failed leading the brake dragging which likely stressed the start cap as that had failed and it
seems led to the triac failing that powered the start winding, when
those were replaced all worked again and it'll soon be fitted back on
the saw to try it in anger.
I know about odd shaft, the dust extractor guy had an old wood planer
and that had a special armature shaft and so had to be rewound at some
cost, 2 speed motor as well so not quite a standard rewind.
My surface grinder motor is largely standard except the armature shaft
and the output end bell is also the belt guard surround and motor mount
so when I replaced the bearings, the seemed fine but at 50 years old
treated it to new, I was especially careful to not damage it as a CI
casting it could be fragile and likely almost unobtainable 2nd hand.
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