Under normal conditions, it is necessary to select the appropriate working mode according to the AC power supply test content.

500kW load bank
 

In the test of AC power supply, dc power supply, battery, DC-DC converter, etc., it is necessary to have a "virtual load" corresponding to the actual load (circuit) that consumes current. Before the popularization of electronic load devices, sliding resistors, power-consuming bulbs, general use of electric heaters, etc. However, these devices also come with inconveniences. For example, AC power supplies are difficult to perform dynamic tests such as load change testing. More importantly, the actual load in its working state is very different, so fine working verification is not possible.

Therefore, if a device has a circuit structure "similar to the actual load mode", it is very convenient to test the AC power supply. Based on this idea, an electronic load device is developed. The initial operation mode of the electronic load device is only constant resistance (CR) and constant current (CC). Later, rechargeable batteries were added to test the required constant voltage (CV) and constant power (CP) modes. These four modes constitute the basic working mode of AC power load device.

However, even the AC power load device operates only in a similar mode to the actual load and is still different from the actual load.