Bel Power Solutions X series of Convert Select DIN rail supplies are primary controlled, AC-DC or DCDC flyback converters with a constant switching frequency of 130 kHz. The power-factor-corrected, single-step conversion of the input voltage to a low output voltage results in extremely high efficiency. Depending on the output power, the converters are fitted with three (375 W) or four (500 W) powertrains.
Models with four powertrains have one or two outputs. Double-output models exhibit individual control of each output.
The input voltage is fed via fuse, filter, and rectifier to the powertrains with main transformers designed in planar technique. The input filter with very small input capacitance generates virtually no inrush current. An input transient suppressor protects the converter against high voltage peaks and surges. Input over voltage and under voltage lockout, as well as input current limitation protect the converter from operation outside of its specification. The input voltage waveform is sensed by the primary control logic to allow active power factor correction, forcing the input current to follow the input voltage waveform.
The secondary side of each main transformer supplies via the rectifier diode a large electrolytic output storage capacitor providing for the hold-up time. Double-output models exhibit individual control logic for each output. The output voltage and the output current are measured and fed back to the primary control logic via an optocoupler. A second control loop monitors the output voltage. It disables the output in the case of a failure in the control logic and limits the output voltage.
Built-in temperature sensors monitor the internal temperature of each powertrain. If the temperature exceeds the limit, the converter reduces the output power continuously to keep the temperature below its limit. A green LED on the front cover confirms the presence of the output voltage(s).
The R input (option R, M1, or M2) allows for external adjustment of the output voltage by means of a resistor or an external voltage source. An external sensor can be connected to the R input and allows for temperature-controlled battery charging.