Posted by Andrew Gabriel on June 26, 2011, 5:40 pm
> wrote:
>> In article
>>
>> > > My feeling is that magnetic ballast mains florries fed via an inverter
>> > > would be very little more efficient than 12 volt halogen lighting.
>> > electronic invertors get over 90% efficiency, the difference between
>> > the 2 is huge
>>
>> That may well be their peak efficiency. But driving an inductive load
>> which requires a decent sine wave? And the efficiency of the fittings is
>> likely poorer too if not getting the correct waveform.
>>
>> It would be very interesting to know the actual efficiency of this setup
>> in practice. I'd say you'd be surprised.
> A switche dmode generated sine is highly efficient. If it wasnt, the
> invertor would cook itself.
It's efficient into a resistive load.
A magnetically ballasted fluorescent lamp isn't a resistive load.
Even if it has a power factor correction capacitor (and most
don't nowadays), that can only correct the inductive component
in the power factor, not the contribution from the tube, which
amounts to about half of it.
The inverter cannot recover the excess energy borrowed from it
and returned each half cycle due to the phase shift, so the load
on the inverter is much nearer to the (higher) VA rating of the
lamp than the power rating. (That's why inverters are rated in
VA and not Watts.)
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
Posted by Andy Dingley on June 25, 2011, 9:44 am
On Jun 19, 11:52pm, The Other Mike
> Currently got a remote observation site (wildlife) with no grid fed
> power nor any prospect of it.
I'd be thinking about solar (keep an eye on Maplin for bargain
clearances), recycled car batteries for low cost, then LED lighting
rather than fluoresecent.
CPC (packaged lamps) and Deal Extreme (bare components and drivers)
are both good sources
Posted by Dave Liquorice on June 25, 2011, 10:18 am
On Sat, 25 Jun 2011 02:44:56 -0700 (PDT), Andy Dingley wrote:
> I'd be thinking about solar (keep an eye on Maplin for bargain
> clearances),
Carlisle has the 3' x 1' 20W (I think) panels at 40 each ATM...
> ... recycled car batteries for low cost, ...
They might not have much deep cycle capacity and car batteries don't
like deep cycles anyway. However if the batteries are free... One
might need to make allowances for acid vapours - ventilation/acid
resistant enclosure.
> ... then LED lighting rather than fluoresecent.
I've not seen any "spray light every where" LED luminaires. They are
all directional to a greater or lesser extent.
--
Cheers
Dave.
Posted by Jim Wilkins on June 25, 2011, 3:40 pm
wrote:
> ...>
> I've not seen any "spray light every where" LED luminaires. They are
> all directional to a greater or lesser extent.
> Dave.
I don't know about wildlife observation labs, but I've managed several
electronics labs and machine shops which all had and needed good
uniform lighting everywhere.
If the work and personnel permit, a light low over the bench like
this:
http://www.employees.org/~bennet/teledesign/lab_bench.jpg
or under the top shelf may be enough.
I like this type:
http://www.halogen-lamps.org/wp-content/uploads/desk-lamp-clamp-9.jpg
jsw
Posted by Andy Dingley on June 25, 2011, 4:02 pm
wrote:
> On Sat, 25 Jun 2011 02:44:56 -0700 (PDT), Andy Dingley wrote:
> > I'd be thinking about solar (keep an eye on Maplin for bargain
> > clearances),
> Carlisle has the 3' x 1' 20W (I think) panels at 40 each ATM...
Check mail order too. I've got one of the 100W panels that I just
clicked on by chance one day when I got a circulated text message
saying that they'd suddenly gone half price again. Shipping was too
cheap to meter.
> > ... recycled car batteries for low cost, ...
> They might not have much deep cycle capacity
So don't cycle them so deeply. Just use more batteries. Car batteries
are available for scrap value and half of that lot collected will
still be usable for capacity-limited low-cost energy projects like
this.
> One might need to make allowances for acid vapours - ventilation/acid
> resistant enclosure.
_Appropriate_ allowance should be made, but if you avoid massive
currents and overcharging, then there's a very lot risk of the sort of
hot outgassing that throws acid vapour around. I've seen one guy break
his arm after slipping on the acid-proofed telephone exchange floor
(those big battery rooms were like swimming pools) and I've seen a
couple of "trustworthy" APC UPSes blow themselves up and spit acid
(rack-mounts UPSes are not a wise idea), but I've never yet seen a
bunch of hippies, a rack of car batteries and a wind turbine have any
trouble.
> I've not seen any "spray light every where" LED luminaires. They are
> all directional to a greater or lesser extent.
LEDs aren't sold as luminaires so much, because they don't need so
much insulation, either electrical or thermal. Many are sold as bare
sticks or even flexible tapes that you're expected to house
yourselves.
It's also quite easy to make your own up from bare LEDs, usually
surface mount, onto a couple of conductors. Insulated wire with knife-
scrape exposures can work for this, or you can buy magic mounting twin-
core wire that's the right spacing and pre-bared at intervals. Even
better is to series them and use a constant-current drive. Cree
SuperFluxs (400mcd @ 130) are under 40p each now by the dozen.
As it's wildlife, you might want to install a set of red lights too.
This will keep your own night vision in better shape, works better in
conjunction with NVGs, or you could simply badger watch with the
lights on.
>> In article
>>
>> > > My feeling is that magnetic ballast mains florries fed via an inverter
>> > > would be very little more efficient than 12 volt halogen lighting.
>> > electronic invertors get over 90% efficiency, the difference between
>> > the 2 is huge
>>
>> That may well be their peak efficiency. But driving an inductive load
>> which requires a decent sine wave? And the efficiency of the fittings is
>> likely poorer too if not getting the correct waveform.
>>
>> It would be very interesting to know the actual efficiency of this setup
>> in practice. I'd say you'd be surprised.
> A switche dmode generated sine is highly efficient. If it wasnt, the
> invertor would cook itself.