At 12:40 AM 21/02/2010, you wrote:
>friends, I inquired of a chinese company about motors and
>controllers for what we need. They sell all types of motors and
>controllers. And seen to be a reputable company. Check out their
>website www.jnkeya.com. cn Check out the low voltage high current
>motors and controllers. Tell me what you think. Thanks Bob (paparonibob)
G'day Bob, All
Hmmm, look-a-like 'copies' of Curtis controllers, Albright
contactors, industrial standard style motos. Typical chinese junky
web site showing confusing specs and mis-labling.
No way to tell by looking, problem is illustrated:
Kelly controllers put out a 400A model, half the price of a
comparable rated Curtis. A few people on the EVDL (electric vehicle
discussion list) got them, and found that they go into thermal
shutdown incredibly early (despite proper heatsinking) .
Curtis 1204, 48V/400A model:
400A/30 seconds, 300A/2min, 210A/5min, 135A/1hour.
The Kelly seems to be something like:
400A/10 seconds, 300A/1min, 175A/5min, 100A/1hour.
So, 48V/100A = 4.8kW out of a controller that shouls nominally do
near to 20kW, but if you're only needing 3kW then that'll be fine.
The short time in 'over current' becomes very significant for an
on-road vehicle, but boats don't have many steep climbing on-ramps to
accelerate up, so probably OK. Just ask them what the 1-hour rating
is (and allow a bit for them being ... enthusiastic) .
Funnily enough, further looking turns up the name Kelly controllers
on their site in the descriptions of some of the controllers (so who
is the manufacturer? )
Contactors: look like copies of Albright contactors. I'm guessing
they don't make them, but are a buy-in to put together their
controller kits. Depends on how well they are made, if they are cheap
enough I'd get one and take the end off and have a look at the
contacts (that'll be where it shows).
Motors: First look seems like they should be OK - foot mount/front
flanged motors in a few kW size, the DC offerings I'd want to see one
that has seen hard service and see how the brush holders and comm
segments are holding up. If their commutators are not moulded
bakelite (but instead are a steel-clamped comm of some kind) that is
an indicator of good things (but most DC motors are on offer have
bakelite, so having moulded bakelite is not neccesarily bad). Brush
holders are likely to be stamped brass, but how thick? How heavy are
the brush tails, what sort of insulation temperature rating (135
degree C insulation is good).
Brushless DC they have 1kW in a 6.5" long, 6.5" diameter/4000RPM so
looks good for an outboard, but... how well does it get rid of the
heat? will it need to be in free air to shed the heat, or can it be
under a fan-vented cowl?
All in all, they may have products that may be good for e-boat
applications, but they'll need to be assessed for the application -
see if they have some in service that you can get a look at. If
they're manufacturing, it may be possible to get them to build a run
of controllers that are heavily conformal coated on the PC boards
(conformal coating is a heavy, flexible layer of a type of varnish
that protects the boards from corrosion) for marine application.
The other thing I notice is they make sep-ex motors, but I don't see
a sep-ex controller, maybe just not listed.
These guys have been around for a few years, they wouldn't stay in
business just making junk (it is much easier to keep a customer than
find a new one). So provided you select their products to meet the
application, they should make stuff that can be used, and be
reliable. Problem is, we're a bunch of hobbiests with all different
applications, they would do the engineering development if we wanted
10,000 of something, but we all want something different.
For someone who is in China, near to one of these manufacturers' ,
there would be an opportunity to be the 'middle man', translate the
manuals into 'real' english, get the real specs (also known as
minimising the warranty claims), make a good margin on the product
but still offer excelent pricing. Trouble there is that you need to
have a background that enables being able to tell if the test being
demonstrated is the same as the specification test.
Regards
[Technik] James
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