Design & Principle Of Operation - Samlexpower SEC-40BRM-230 Owner's Manual

SeCtION 3 |
The unit is designed using advanced switch-mode technology and active load share cir-
cuitry for high reliability, high efficiency and minimum size and weight. It is modular in
construction consisting of up to 5 base level PCB modules (referred to as "PSM" – power
supply module) that are connected in parallel with true current sharing. Each PSM is a
stand alone power supply which delivers up to a maximum of 20A continuous. By equal-
izing the output currents, uniform thermal stress of the individual PSM is ensured which
has utmost importance for long term reliability of electronic components. The operat-
ing principle of the current share mechanism is to measure the output current of each
PSM and to be able to modify the output voltages of the PSMs until all the participating
PSMs deliver equal output current. Typically, the output currents of the paralleled PSMs
will be within 10% of each other at full output current. one of the modules automati-
cally assumes the role of a master and the others operate as slaves. Each PSM is required
to be interconnected with one another to a common "ShARE BuS" through a pair of
parallel pins marked "Jump 1" and jumper wires ( fig.1 and 2).
for proper operation of the current share control circuitry, a minimum load current is
required to flow through each PSM to produce adequate feed back signal. This mini-
mum pre-load current is provided by the sum of the currents drawn by the fans and by
an internal static load resistor connected across the load output terminals. This internal
pre-load current* is kept to the minimum to reduce dissipation.
note:
it is likely that due to the drift in the pre-set values, the minimum internal preload
current may not be sufficient to provide adequate feedback signal strength resulting
in shut down of one or more modules when no external load is present (the associated
pSm status led will flash and also, the associated signal for remote indication will oscil-
late between high and low). As soon as external load is applied to the unit, the feed
back signal strength will increase and the pSm(s) that were shut down will also operate
normally.
The output is delivered through an isolating Schottky Diode to enable connection of
external battery for un-interrupted DC power output. The external backup battery is
kept charged by taper charging through a series resistor.
• SEC-100BRM-230 HAS 5 PSMs of 20A EACh PRoVIDINg A ToTAL of 100A
• SEC-80BRM-230 HAS 4 PSMs of 20A EACh PRoVIDINg A ToTAL of 80A
• SEC-60BRM-230 HAS 3 PSMs of 20A EACh PRoVIDINg A ToTAL of 60A
• SEC-40BRM-230 HAS 2 PSMs of 20A EACh PRoVIDINg A ToTAL of 40A
Design & Principle of Operation
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