Operating Principle :
The unit of a DC Power Supply and a Battery Charger. In the presence of AC Voltage the unit delivers power to the load as well as the battery. When mains fail the battery supplies power to the load. When the battery voltage reaches 11.2 Volts the battery is cut off from the load to prevent the over discharge.
The charger has 3 modes of operation, one is Constant Voltage Mode (Float Mode) and other is Constant current Mode (Boost Mode) Taper Mode for deep discharge. The float or boost mode is selected automatically depending upon the status of battery. In the float mode the battery voltage is kept at 13.2 volts (can be set by preset). In this mode the battery draws only tricle charging current required to make up for its internal losses.
In the boost mode the charger output voltage is gradually increased to 14.4 volts (settable by preset) keeping always the battery charging current constant (5 Amps constant current charging). When the battery voltage reaches the 14.4 volts level, the charging mode is changed automatically to float mode.
SPECIFICATIONS :
| AC Input | 170 to 270 VAC (47 - 53 hz 1 Phase) |
| DC Output | 13.2 Vdc (Float) 14.4 Vdc (Boost) |
| O/P Current | 7 Adc (Load) 5 Adc (Battery) |
| Line Regn. | Better than 1% |
| Load Regn. | Better than 1% |
| O/P Ripple | 100 mv p-p at full load |
| Efficiency | Better than 75% |
| Operating Temp. | 0 - 55 Deg. C. ambient |
| Protections |
1. Short circuit
& overload on both batt & load. |
| Indications | 1. Float 2. Boost 3. Battery overdischarge 4. Mains On |
| Terminations |
Output : Load
and batt on separate Terminal strips |
| Dimensions | L x B x H = 17.5 x 9 x 17.5 cm |
Advantage of switch mode FCBC with conventional FCBC :
1. High Efficiency.
2. Small size and less weight.
The voltage control in conventional FCBC is done by means of a Triac or SCR preregulator which provides coarse control and fine control is achieved by means of a voltage dropping device which is a series pass resistor. This results in high power dissipation and low efficiency. Also since the step down function is done by a line operated 50Hz transformer, the equipment tends to be bulky.
In contrast in switch mode FCBC the regulation is achieved by means of PULSE WIDTH MODULATION of the switching device. Thereby the efficiency achieved is very high (80%).
Also the voltage step down function is done by using high frequency (30 KHz in the present case) ferrite cores which results in small size and less weight.
3. Single PCB construction resulting in less wiring and less workmanship flaws.
4. Better Transient response to both load and line changes.
5. Wide Operating Range.