OT: LED lighting configuration... - test-drb@ccmp.vtda.org

29 Apr 2016

...
  On Apr 29, 2016, at 3:32 PM, Bill Sudbrink
<wh.sudbrink at verizon.net> wrote:

 ... The "bulbs" are labeled:

 15F18120-45 15 watt 36vdc constant current

 I'd like to put four in a fixture and I'm trying to
 understand what kind of driver I need and how to wire
 it.  I was thinking of using a Mean Well LPF-60D-36
 like this:

 http://www.ebay.com/itm/Mean-Well-LPF-60D-36-AC-DC-POWER-SUPPLY-Dimmable-LED
 -DRIVER-36V-60W-CLASS2-/161857068172?hash=item25af6edc8c:g:9hQAAOSwA4dWHVn5

 and wiring the "bulbs" in parallel to it.  But after
 realizing that I'm not completely sure what a "constant
 current" power supply does and doing a little "googling"
 I don't know if that's the right approach. 
A constant current supply is one that delivers a constant current to a varying load
(within limits) just as a constant voltage supply delivers a constant voltage to a varying
load.  Constant voltage is the typical "regulated power supply".  Constant
current is needed for loads whose behavior is tied to a particular current, especially if
those loads have negative dynamic resistance (such as gas discharge tubes, e.g.,
fluorescent tubes).

If you have multiple loads that want the same constant voltage, connect them in parallel. 
If you have multiple loads that need constant current, connect them in series, NOT in
parallel.  The whole point of constant current applications is that the impedance of the
loads is not consistent, and if you connect them in parallel, the current through each
individual load will not be the correct value.

	paul