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Posted by houstonceng on June 5, 2008, 4:29 pm
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> In view of my cack-handed wrecking of my S7 motor (see separate thread),
> I am looking at a potential excuse to spend some cash on a 3-phase motor
> and inverter drive. Always liked the potential for speed control, good
> torque at low speeds, smoother running etc and was toying with such an
> upgrade anyway.
>
> I have looked at the advertisers in ME; I quite liked the look of the
> Newton Tesla package for the S7. Anyone out there got any comments on
> these or other competing versions? Do I need the 1 HP or will the 1/2 HP
> do? (The price difference is pretty small so I'd instinctively go for
> the 1 HP). Anything else I need to think about?
>
> David
> --
> David Littlewood
David
If you don't have the basic Electrical knowledge to fit the inverter,
set the parameters on the VFD (Inverters) and wire the controls with
appropriate interlocks (or have someone who can to advise you), go the
Newton-Tesla route. A little expensive but safe.
Gavin O or E-bay units are often older models of VFD and you may not
be able to get the instructions allowing you to set it up (change the
parameters). Previously owned usually means limited (sometimes no)
gurantee. I don't think the prices are always low either. You need
to gave a good "feel for the deal"
Drives-direct do some good "packages" and, judging by their adds in ME/
MEW, have "moved up on the supplier ladder". They certainly advertise
assistance and control systems. Again, may not be as low priced as
other routes - but you'll have "on-line help".
Finally, the RS route is a good bet - assuming you have the basic
Electrical knowledge (or access to someone who does). Bear in mind
that you'll need a gew more bits and - as RS supplies to the trade -
you'll get lottle back-up and you'll need a "trade account" with
them. Maplin don't sell VFDs.
Just remember, if you can blow a single-phase motor it's even easier
to blow your 3-phase ditto and a VFD if you don't know what you're
doing.
Regards
Andy
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Posted by David Littlewood on June 5, 2008, 5:58 pm
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In article
>
>David
>
>If you don't have the basic Electrical knowledge to fit the inverter,
>set the parameters on the VFD (Inverters) and wire the controls with
>appropriate interlocks (or have someone who can to advise you), go the
>Newton-Tesla route. A little expensive but safe.
>
>Gavin O or E-bay units are often older models of VFD and you may not
>be able to get the instructions allowing you to set it up (change the
>parameters). Previously owned usually means limited (sometimes no)
>gurantee. I don't think the prices are always low either. You need
>to gave a good "feel for the deal"
>
>Drives-direct do some good "packages" and, judging by their adds in ME/
>MEW, have "moved up on the supplier ladder". They certainly advertise
>assistance and control systems. Again, may not be as low priced as
>other routes - but you'll have "on-line help".
>
>Finally, the RS route is a good bet - assuming you have the basic
>Electrical knowledge (or access to someone who does). Bear in mind
>that you'll need a gew more bits and - as RS supplies to the trade -
>you'll get lottle back-up and you'll need a "trade account" with
>them. Maplin don't sell VFDs.
Andy,
Thanks for these thoughts. I have no problem with single phase switch
units and am also OK with 3 phase on paper (though no direct experience)
- and I have a friend who is an ex-RN electrical engineering officer if
I need any assistance. For me it's the time - pricing up the RS stuff
with all the bits and bobs needed, plus VAT, and the difference starts
to look fairly modest even before you reckon all the extra work
involved. I'm sure if I was prepared to wait and spend time it could be
done for half the cost, but there are other things I'd rather do.
And I do know what you mean about the instructions - I have a
3-phase/inverter on my T&C grinder, bought second-hand with no
instructions, and I have no idea how to change anything. Fortunately it
is not the sort of machine where I need to, so I have just let well
alone.
>
>Just remember, if you can blow a single-phase motor it's even easier
>to blow your 3-phase ditto and a VFD if you don't know what you're
>doing.
>
The jury is still out on what happened - I hope to dismantle the motor
assembly this weekend, tedious job as the lathe is hard against a wall
and too heavy to move easily - but I'm pretty sure the motor is not
burned out. It is locked solid, won't turn even a tiny fraction of a
degree (and yes, the clutch etc. is all disengaged). I am wondering if
something has got into the casing, or the centrifugal switch has fallen
apart or something.
David
--
David Littlewood
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Posted by DAVE on June 5, 2008, 6:46 pm
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Bear in mind
> that you'll need a gew more bits and - as RS supplies to the trade -
> you'll get lottle back-up and you'll need a "trade account" with
> them.
>
No need for a 'trade account' with RS, I've been buying from them for many
years without any kind of trade account (maybe I ought to open one !!).
Brad.
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Posted by Tony Jeffree on June 5, 2008, 7:27 pm
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> Bear in mind
>> that you'll need a gew more bits and - as RS supplies to the trade -
>> you'll get lottle back-up and you'll need a "trade account" with
>> them.
>>
>
>No need for a 'trade account' with RS, I've been buying from them for many
>years without any kind of trade account (maybe I ought to open one !!).
>Brad.
Yep - anyone can buy from RS; the difference is that if you have a
trade account, the postage is free (as long as you order via the web).
Used to be a guaranteed next day delivery too...not quite that good
nowadays but never taken more than 2 working days.
Regards,
Tony
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> I am looking at a potential excuse to spend some cash on a 3-phase motor
> and inverter drive. Always liked the potential for speed control, good
> torque at low speeds, smoother running etc and was toying with such an
> upgrade anyway.
>
> I have looked at the advertisers in ME; I quite liked the look of the
> Newton Tesla package for the S7. Anyone out there got any comments on
> these or other competing versions? Do I need the 1 HP or will the 1/2 HP
> do? (The price difference is pretty small so I'd instinctively go for
> the 1 HP). Anything else I need to think about?
>
> David
> --
> David Littlewood