Motor current limits

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Motor current limits

Dan Frederiksen-2
I just did some calculations on heat build up in the wires of the
Chinese motors based on the given wire thickness.
the 35mm2 wire would take around 26 seconds to go from 20 Celsius ('room
temp') to 150 Celsius insulation limit at 1000A. (assuming no cooling at
all or heat transfer to the rest of the motor)

at 1000A their small motor ZC5-48 at 41kg would develop and uncharted
but projected torque of 300Nm. at 8000rpm that's 336HP : )
(would require maybe 350V @1000A to accomplish)

11.5seconds to overheat at 1500A.
as you can push the limits of current (by quite a margin) you can
perhaps push the limits of the insulation. it's rated at 150C but might
go a bit further for a short time without disintegration thus giving an
extra margin of performance.

even assuming no heat transfer to the rest of the motor and air it would
take 11 minutes to overheat at 200A

it would appear the motors are quite viable for EV use. should I get to
the motor buying stage I will probably choose such a Chinese motor.

Dan


Was it Berube who said his 11 inch motor doesn't heat up significantly
during a drag? iirc that would appear to verify a hideous short time
power surplus in the motors as long as they remain mechanically intact
and brushes don't quit. we just have to keep it secret from the Ferraris
that it's only a short time power surplus. they wont figure it out on
their own :)
Michaela, this is not just drag considerations. this means normal
driving can do with smaller, cheaper, lighter. :)  I don't have a price
for the ZC5 but it must be below 400$

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Re: Motor current limits, correction

Dan Frederiksen-2
the data should be accurate except for the weight. because of the
confusing naming convention it was not a small motor weighing 41kg but
65kg.
the price is 390$ wholesale and 486$ sample (that's the first mention of
a sample pricing policy but what can you do..)

Dan

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