DESCRIPTION
This is a 19 inch, 2U height (3.5”) Rack Mount Power Supply which converts 230 V ,
50/60 Hz. AC power into regulated 14.2 V DC , +/- 1% (At module output*) delivering
up to a maximum of 100 A continuous ( up to 115 A surge ) with 5 Base Level PCB
Modules. There is provision to connect the power supply to an external battery for
backup power in the case of an AC power failure and re-charge the battery when AC
power resumes.
*
Voltage at output terminals Load+ & Load- will be 13.8V nominal (Please see page 7 for explanation.)
APPLICATIONS
The unit is designed for the following applications:
1.
N+1 redundant systems
2.
Future power level expansion
3.
Uninterrupted DC output when used in conjunction with an external battery backup.
DESIGN AND PRINCIPLE OF OPERATION
The unit is designed using advanced switch-mode technology and active load share circuitry for high reliabil-
ity, 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 20 A continuous. By
equalizing the output currents, uniform thermal stress of the individual PSM is ensured which has utmost
importance for long term reliability of electronic components. The operating 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 paral-
leled PSMs will be within 10% of each other at full output current. One of the modules automatically 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 minimum 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 termi-
nals. 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 oscillate 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-220 has 5 PSMs of 20 A each providing a total of 100 A
•
SEC-80BRM-220 has 4 PSMs of 20 A each providing a total of 80 A
•
SEC-60BRM-220 has 3 PSMs of 20 A each providing a total of 60 A
•
SEC-40BRM-220 has 2 PSMs of 20 A each providing a total of 40 A
COOLING AND WARNING FOR FAN FAILURE
The heat generated due to internal power dissipation is removed by forced cooling
through two high power D.C. fans mounted at the back of the unit which suck air from
the vents on the sides of the unit & blow outwards from the rear of the unit.
IT IS EXTREMELY IMPORTANT THAT THE DISCHARGE SIDE OF THE FANS
AND THE SUCTION SIDES OF THE VENT SLOTS ARE NOT BLOCKED.
3.
