Samlex America SEC-4825BRM - Manual (Page 10)

10 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 11
From the above equation, it will be seen that the battery will be charged at a maximum
charging current of around 2A when the battery is completely discharged to Stand-
ing Voltage of 42.8V and the charging current will taper to a very low value of around
25mA when the battery is charged to Float Voltage Level of 54.6V.
If input A.C. power is interrupted, the external battery feeds the load instantaneously
through the Schottky Diode D2 (D2 will be forward biased and will by-pass resistors R1
& R2). Voltage available to the load will be approximately 0.2V lower than the battery
voltage due to forward voltage drop across D2. Availability of AC power is signaled for
remote monitoring through opto-isolated signal through D-Sub Connector (Pins 2 and
16 of D-Sub Connector, Fig 3.2. Also see below under “Remote Monitoring of Opera-
tional Status”). This signal may also be used to indicate that the load is being powered
by battery (In case external battery is used for battery back-up). When AC input power
returns, load current will be supplied by the Power Supply Section, Diode D2 will be re-
verse biased and the discharged battery will be taper charged through 6 Ohm effective
resistance of R1& R2.
* NOTE: The value of charge limiting resistors R1 and R2 is based on a typical 48V,
25Ah deep cycle marine battery. If a different type of battery is used, the value of
the resistor should be adjusted to meet associated charging requirements.
REMOTE MONITORING OF OPERATIONAL STATUS
A provision has been made for remote monitoring of the following operational
conditions and parameters:
a) Operational status of the 5 Power Supply Modules (PSM)
b) Failure condition of the cooling fan(s)
c) Availability of AC input power (Through 120VAC to 5VAC transformer)
d) Output voltage measurement (Across Load Terminals)
e) Output current measurement (Voltage across an internal shunt with Shunt Ratio of
25 mV / 50A or 0.5 mV per Amp)
Signals for remote monitoring of operating conditions at Srls (a), (b) and (c) above are
transmitted to the remote receiving device through open Collector and open Emitter
pins of phototransistor of internal Opto-Isolator (Figs 3.2 & 3.3A).
Outputs for voltage and current measurements at Serials (d) and (e) above are direct
analogue voltages.
The Pin Out of the 25 Pin D-Sub Connector (12, Fig 2.1) providing the above signals for
user interface is given at Fig 3.2.
Section 3 | Design & Principle of operation
11001-SEC-4825BRM-0114.indd 10 14-01-07 1:15 PM