Electronic Load
An electronic load is a device or an assembly as a replacement for a conventional ( resistive ) load resistance (input resistance, terminator, external resistance ) is employed. In the diagram it is like a resistor component represented by a rectangle and usually referred to as ' R' without index, which stands for an arbitrary, unspecified load.
As a counterpart to the power source is in the Electronic Load to a current sink. While having a fixed resistor always only a certain load current can be set at a certain resistance value when a load is a power source, is the peculiarity of the electronic load, the load current can be adjusted in a defined area, it is electronically controlled.
The power consumed by the electronic load, electric power is mostly converted into heat, for cooling and removal of the exhaust fan or water cooled elements may be used. Also fed back into the public power supply network is possible under certain conditions. Electronic loads are used in various applications, especially for testing the power and control equipment, batteries, fuel cells and solar cells, generators. Are AC loads for testing of transformers, uninterruptible power supplies (UPS ) or vehicle electrical systems used.
The power and range of features of these devices begin with the simplest circuits that consist essentially of a potentiometer for setpoint adjustment and a load circuit. The load circuit is formed, for example, a power MOSFET, which converts the received power into heat. For advanced Electronic Loads several modes of operation are present, mostly this constant current, voltage, are power and resistance. Also now a part of the drivability over analog or digital control signals from a control unit such as programmable controller or the PC to the operation amount. This can be simulated repeatable load special forms such as short pulse loads or switch- specific with different load curves of consumers. Setpoints and measured quantities such as input voltage and actual load current are displayed in analog or digital and transmitted via the control interface.
Function Example
The adjacent circuit diagram is the operating principle of an electronic load clarify: With the potentiometer at the base of the transistor, an emitter voltage is set so that flows through the load resistor, a certain power.
, The load resistance of, for example, an ohmic resistance and represents one of an emitter voltage that is also applied to the load resistor, a so that a current from flowing through.
Based on this scheme can be produced real electronic loads, however, have to stabilize the load over a control. A stabilization of the load is often useful for example, to compensate for the temperature dependence of the resistance and the electronics.