Electronic DC Loads

Programmable electronic DC loads simulate defined electrical loads by drawing controlled current from a power source or device under test (DUT). Depending on the model, they operate in constant current (CC), constant voltage (CV), constant resistance (CR), or constant power (CP) mode. This enables stable and reproducible testing of power supplies, batteries, fuel cells, DC/DC converters, and other power electronic devices in development, laboratory, production, and automated test equipment (ATE).

The ET System portfolio includes compact benchtop electronic loads, multi-channel DC loads, high-current DC loads, high-speed electronic loads, and high-voltage DC loads above 600 V. Available solutions range from compact low-power instruments to scalable high-power systems.

The appropriate electronic load is selected according to the required voltage, current, and power range as well as minimum operating voltage, dynamic response, number of channels, measurement accuracy, communication interfaces, and mechanical integration. For supplying a DUT, explore our programmable DC power supplies. Applications requiring both power sourcing and energy absorption may benefit from a bidirectional DC power supply.

How to Select an Electronic DC Load

Selecting a suitable electronic DC load starts with the electrical characteristics of the source or device under test (DUT). In addition to maximum voltage, current, and power, the complete operating range, minimum input voltage, dynamic behavior, measurement requirements, automation interfaces, and mechanical integration should be considered.

• Voltage, current, and power: Define the required voltage, current, and power combinations across the complete test sequence. Maximum voltage, maximum current, and maximum power may not always be available simultaneously. The operating area and applicable derating limits should therefore be checked.
• Minimum operating voltage: An electronic load requires sufficient input voltage to draw the specified current. For low-voltage, high-current applications such as fuel-cell or battery-cell testing, verify that the required current can be achieved at the minimum DUT voltage.
• Operating modes: Common operating modes include constant current (CC), constant voltage (CV), constant resistance (CR), and constant power (CP). Depending on the application, combined modes, short-circuit simulation, battery discharge, or LED simulation may also be relevant.
• Dynamic performance: For transient testing, check the current slew rate, rise and fall times, minimum pulse duration, switching frequency, and support for programmable dynamic sequences. High-speed DC loads are particularly suitable for testing the transient response of power supplies and DC/DC converters.
• Channels and isolation: Multi-channel electronic loads are suitable when several outputs, circuits, or DUTs must be tested independently. Check the number of channels, power available per channel, channel isolation, and whether channels can be operated in parallel.
• Accuracy and measurement: Consider the accuracy and resolution of voltage, current, power, and resistance measurements. Low-current applications may require additional measurement ranges or higher resolution for leakage-current testing.
• Interfaces and automation: For automated test equipment (ATE), verify the available communication interfaces, remote-control commands, sequence functions, trigger options, data acquisition, and software compatibility. Depending on the series, relevant interfaces may include LAN, CAN, RS232, RS485, USB, SCPI, analog control, and digital I/O.
• Protection and safety: Check the available overvoltage, overcurrent, overpower, and overtemperature protection as well as reverse-polarity protection, external shutdown, interlocks, and status outputs.
• Mechanical integration and cooling: Determine whether a portable or benchtop unit, a multi-channel chassis, or a 19-inch rack-mount system is required. High-power dissipative loads also require sufficient ventilation and may generate considerable heat.
• Parallel operation: For higher current or power requirements, verify whether the selected series supports parallel or master-slave operation and which limits apply to the combined system.
• Dissipative or regenerative operation: Conventional electronic loads convert the absorbed electrical energy into heat. Regenerative systems return the absorbed energy to the mains and can reduce heat generation and cooling requirements. If the DUT must both receive and return energy, a bidirectional DC power supply may be the more suitable solution.

For application-specific test benches, ET System can combine electronic DC loads, power supplies, measurement equipment, safety components, and control systems through test system integration. For support with selecting a suitable electronic load, contact our technical sales team.