Posted on: July 1, 2014

What are Electronic Load?

An electronic device designed to provide a load to the outputs of a power supply, usually capable of dynamic loading, and frequently programmable or computer controlled.

Real loads are complex and deviate from being purely resistive, inductive or capacitive. The electronic load mimics the real load that a power source sees in the actual application, but unlike the real load which can be unpredictable and random in value, the electronic load provides an organized, contained and a fully controllable load.

The electronic loads help designers to test electronic power products and ensure quality, reliability, and performance.

Electronic loads are available for both ac and dc supply testing. Most electronic loads have capabilities to emulate various modes including dynamic, constant power, constant-voltage, constant current, constant resistance, power factor, crest factor or short circuit modes. The loads can be programmed to dynamically change the mode to emulate changing load conditions.

Type of Electronic Loads

There are four common types of electronic loads:

  • Benchtop: These are entry level, inexpensive electronic loads, but are limited in range and accuracy.
  • Slot: Measures a single set of variables, similar to benchtop
  • System: For near-continuous duty, consists of an integral transient generator, provides a variety of features and are more expensive.
  • Modular: These consist of a computer chassis and designed for dynamic loads. These vary depending on the number of loads per chassis. The modular loads are capable of testing several different supplies connected in parallel, in just a single pass. (i.e. a computer power supply with multiple outputs)

The electronic loads differ in their input voltage, current, power, and frequency. They are available in various configurations to cater for almost any load, whether high current, high voltage or high power, dynamic or any type of load. To increase capacity, the loads are connected in parallel to get powers of as high as 120KW. Where extra cooling is required forced air or water cooling is used.

The electronic loads may include an analog display, a PC interface such as the USB, RS 232, or GPIB. These are used to record tests data, and controlling the parameters of the DC load.

The seven common measurements types include:

  • Voltage
  • Current
  • Peak-current
  • Frequency
  • Crest-factor
  • Power-factor
  • True power

The selection of an electronic load is based on the desired application and the testing to be done, some of the factors considered include:

  • Highest and lowest voltage points that the electronic load should read
  • Kind of measurements required
  • Highest current operating point
  • Whether the testing will be on one unit per test or several units at a time
  • Whether the load is dynamic and easily configurable to accommodate changing applications

Electronic loads have various applications including design verification, power supply and converter testing, current modulation, voltmeter fuse, troubleshooting devices for repairs, etc.

  • DC loads are used for testing DC power supplies, fuel cells, batteries, battery chargers, converters, telecommunications rectifiers, etc.
  • AC loads are used to test single phase and 3 phase ac power systems such as power inverters, UPS systems, automatic fuses and switches; and from renewable energy sources like the solar panels and windmills.