American Reliance’ SPS Series combines the best of dc power processing with multiprocessor embedded control. A combination of high and medium frequency power processing technologies improves response, shrinks package size, and reduces cost. SPS Series power supplies are current fed and are more tolerant to abusive loads than conventional switching power supplies. SPS Series power supplies offer an unusual blend of both analog and digital control. Two front panel potentiometers are available to set voltage and current for stepless analog control. Alternatively, voltage, current, over voltage trip, and over current trip may be programmed through a rear connector via resistance, voltage, or current. With simple configuration changes, the SPS Series power supplies will accept keypad entries and up/down key presses for programming voltage, current, over voltage trip, and over current trip. Key strokes are kept to a minimum by a repeat last command feature. RS232 communications is embedded in the control circuitry allowing full computer control with SCPI commands. An optional IEEE-488 to RS232 converter, Ethernet to RS232 converter, and other communications converters are available to echo commands over the communications bus. SPS Series power supplies can be configured through the front panel for different applications. The power supply can be programmed to have its control functions accessible from the front panel, rear connector, or through RS232 communications. Sensing can be established at the output terminal of the power supply or through a rear terminal block for sensing at the load. An external interlock can be set to enable operation only when an external connection is made. Even calibration has been simplified with front panel access to calibration digital potentiometers. SPS Series power supplies incorporate an optically isolated feedback system. The result is that all user interface circuitry is reference to earth ground -- not the negative terminal of the power supply. This enables users to connect external circuitry without concern of ground loops or voltage breakdown. SPS Series power supplies offer both master/slave parallel and series operation. This enables two or more power supplies to be placed in parallel for increased output current or in series for increased output voltage. With master/slave operation, power supplies operate at near equal voltage and current. SPS Series power supplies can operate as a voltage source or current source depending on the control settings and load conditions. If the power supply is operating as a voltage source and the load increases to a point beyond the current command setting, the power supply automatically crosses over to current mode control and operates as a current source at that setting. One-hundred memory states are available to program voltage, current, over voltage trip, over current trip, and time period. Set points can be auto sequenced with time or external triggering. Special programming codes allow repeating to create a power function generator. The first 10 memory states are displayed on the front panel to simplify programming tasks. SPS Series power supplies offer an analog input to modulate the voltage or current setting. This feature enables the voltage or current setting to be adjusted by a sensor input, such as a thermistor, or by monitoring its own voltage or current. Modulation allows the output to be tailored for advanced process control applications, battery charging, and source emulation. Remote Interface Software is included to provide sophisticated computer control. This software provides a virtual control panel to emulate the power supply’s front panel, a command panel to send and monitor SCPI commands, a register panel to monitor registers, and a calibration panel to provide easy access to calibrate digital potentiometers. SPS Series power supplies have extensive diagnostic functions -- all of which when activated take command to shut down the system. Diagnostic functions include phase loss, excessive thermal conditions, over voltage trip, over current trip, fuse clearing, and program line. Program line monitors externally applied analog set point signals to insure they are within the specified range. Upon a diagnostic fault condition, main power is disconnected and the diagnostic condition is latched into memory. Pressing the clear key clears the memory. All diagnostic functions can be monitored through a rear connector. Furthermore, control functions can also be set through the rear connector to allow simultaneous control of one or more SPS Series units. SPS Series supplies have three levels of over voltage/current protection: shutdown of controlling insulated gate bipolar transistors (IGBT’s), disconnect of main power, and input fuses. After an over voltage/current trip condition, the supply must be reset. SPS Series have push button start/stop controls. These controls are tied to a mechanical contactor which operates with the electronic switches to break the ac mains when stop is commanded. Unlike competing products, an off means both an electrical and mechanical break in the power circuit — not a break in an electronic switch. Safety comes first at American Reliance.