The Dependable Power Systems Battery Charger is a solid-state, constant voltage, current limited rectifier/charger unit that provides clean, isolated DC power.
The rectifier/charger consists of the input isolation transformer (T1), rectifier/charger control board (PC1), three SCR's (SCR1 to SCR3), three diodes (D1 to D3), two fuses (FU1 to FU2), and an inductor (L1), connected in a 3 phase full wave bridge. On filtered units an additional inductor (L2) and capacitors (C7 & C8) are provided.
The input transformer isolates the battery from the AC input line and provides the correct voltage, via FU1 and FU2 to feed the full wave bridge (SCR1 to SCR3 & D1 to D3). The control windings on T1 supply the power and phase information to the rectifier/charger control board.
The full wave bridge (SCR1 to SCR3 & D1 to D3) converts the AC from T1 to DC which powers the any DC loads and charges the batteries. The DC loads run on the rectifier output as long as it remains higher then the batteries. As the AC input goes lower then -10%, the batteries first share in powering the loads, then takes over completely. The inductor is used to limit the surge current and smooth the ripple.
The rectifier/charger control board regulates the output voltage and limits the output current of the rectifier/charger by varying the phase angle at which the SCR's are turned on. Besides controlling the regulation and current limit, the control board provides a walk-on feature, which slowly raises the voltage and current when the AC input is first applied. The rectifier/charger control board also includes a separate overvoltage regulator that limits the output voltage independent of the primary regulator and provides an overvoltage indication. Fuse blown (FU1 to FU2) indicators are also included on the control board.