Electronic Load Fundamentals | Keysight
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Electronic Load Fundamentals | Keysight

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Download this white paper to understand the fundamentals of an electronic load and how to select an electronic load that best fits your test requirements. Topics covered include:

What is an electronic load?
An electronic load is a test instrument designed to sink current and absorb power out of a power source. If a power supply is used to power a device, an electronic load is used to test the power supply by emulating the device under test (DUT). Power supplies and electronic loads are complementary test equipment. The power supply tests electronic circuits under specific sourcing conditions. The electronic load tests the energy sources or energy conversion blocks under specific loading constraints. An electronic load is a programmable instrument that offers the user various modes of control such as constant voltage (CV), constant current (CC), constant power (CP) or constant resistance (CR).

Who uses electronic loads?
Device manufacturers and design engineers use electronic loads to test numerous power devices such as power supplies, DC-DC converters, chargers, adapters, batteries, solar panels, fuel-cells, and more.

Why do engineers use electronic loads instead of a fixed value power resistor?
In situations where you need a purely resistive load and no closed loop control is required, it is sufficient to use a fixed value power resistor. A fixed value resistor presents many limitations. It is not adequate for loading and testing power sources that have complex testing requirements. Such tasks require sophisticated electronic load features to validate the various states of operation.

How and where to use different DC Electronic Load Operation Modes including:

  • Constant current operation mode
  • Constant voltage operation mode
  • Constant resistance operation
  • Constant power operation

Electronic Load Applications including

  • Power converter and inverter testing: This is a fast way to test DC-DC and AC/DC converters. The electronic load helps to simulate the power-on process of the device. You can test the minimum and maximum input turn-on voltage level with different load levels. You can carry out ripple, noise, load/line regulation, over voltage, and current protection tests with the electronic load.
  • Uninterruptible power supply (UPS): This is a complete test that requires an AC source, DC source, DC load, and AC load. The DC load uses the load bank to test the backup battery and charger within the UPS. An AC load tests the entire UPS system. A load bank test indicates the UPS’s ability to provide the necessary power, voltage stability, and efficiency of control systems under varying load conditions.
  • Batteries and fuel cells: Use constant loading to reduce the test time in comparison to resistor load banks. To test the capacity, use the CP mode to provide a consistent power drain as the battery voltage drops over time. The electronic load’s capability to program different load profiles with a fast transition enables profile testing for battery charge and discharge cycles.
  • Solar panels: This is a good solution for high-power photo voltaic testing as solar panels can sink high current at a lower cost. Use the CV mode to capture the I-V curve and incremental voltages to measure the current. With portable devices, program the e-load to simulate various device power states such as sleep, power conservation, and full power modes for a power consumption test.
  • Portable devices: Use the electronic load to simulate various device power states such as sleep, power conservation, and full power modes to test power consumption.

 How to Select the Right Electronic Load based on:

  • Form factor
    - Choose a modular, small form factor solution to give you the flexibility to scale for future expansion for automated test equipment (ATE).
  • Capacity rating
    - Ensure your electronic load safely manages the capacity of your power source.
    - Check that the electronic load range of operations cover your maximum voltage, current and power requirements.
  • Speed
    - Choose a load to emulate fast waveforms with the appropriate slew rate.
    - Verify the load can generate and measure the signals of your application with adequate bandwidth.
    - Choose a load with a programmable slew rate and ON|OFF delays to control sequencing.
    - Select a load with superior command processing time and output speed to improve and maximize your system throughput.
  • Operating modes
    - CC for a power consumption test
    - CR for replacing a resistor
    - CV to test current source
    - CP to test storage capacity
  • Dynamic testing
    - Identify a dynamic load with arbitrary function generation capabilities and built-in waveforms to test sine, pulse, step, ramp, or to import your profiles.
    - Ensure the load has sufficient sample rate to generate/ measure fast transient signals and sufficient memory.
    - Verify the load generates the arbitrary dynamic waveforms for necessary modes
  • Flexibility
    - Choose a modular system to mix and match different modules – electronic load and power modules – within the same unit.
    - Synchronize within a single environment to achieve a turnkey solution.
  • Protection features
    - Confirm the load has built-in protection features for overvoltage, overcurrent, overpower, and overtemperature.
    - Ensure shut down features to avoid hazardous conditions on your DUT.
  • Computer control
    - Load connectivity interfaces for remote programming and controlling of your instrument – GPIB, LAN, or USB.