- Input voltage
- 0 to 150 V on four models; 0 to 500 V on four models
- Input current
- 0.1 mA to 60 A, 120 A or 240 A depending on model
- Input power
- 600 W, 900 W, 1200 W or 1500 W depending on model
- Load modes
- Constant voltage, constant current, constant power, constant resistance, short circuit and open circuit
- Sampling
- 500 kHz analogue-to-digital conversion, with Vpp, Ipp, Vp+ and Vp- measured in real time
- Dynamic test
- Up to 50 kHz, with settable current slope and pulse width from 0.010 ms to 999 s
- Battery test
- Capacity to 9999 AH, discharge time to 4294967295 s, with internal resistance and curve plotting
- Stored setups
- 100 internal and 500 external on a USB drive
- Interfaces
- RS232C, electrically isolated, with SCPI commands; USB host for data export and firmware
- Body
- 430 × 88 × 450 mm
An electronic load is the instrument that lets a power supply be tested at the current it was designed for, without a bank of resistors and without the heat they produce. This range sinks up to 240 A or 500 V, in eight combinations of voltage, current and power, with the test functions a modern supply needs.
Product overview
Eight models divide into a 150 V class and a 500 V class. Within each class the power rises from 600 W to 1500 W, and the current rises with it, so a low-voltage bench can have 240 A while a high-voltage bench stops at 60 A or 120 A.
The front panel is a 4.3 inch colour screen with a numeric keypad, four soft keys and an adjustment knob, and the interface can be set to English or Chinese. The rear carries the input terminals, a current monitor, the RS232C connector and the voltage selector.
How the programmable DC electronic load works
The load is a power stage that sinks current from the source under test. In constant current mode it holds the current at the set value whatever the source voltage does; in constant voltage, constant resistance and constant power modes it holds that quantity instead, and in short and open modes it presents the two extremes.
The measurement is taken at the terminals, by a converter sampling at 500 kHz. That rate is fast enough to report peak-to-peak values and the positive and negative peaks, not just an average, which is how the ripple of a switching supply and the transient of a load step are seen rather than smoothed away.
Dynamic testing switches between two current levels at up to 50 kHz with a settable slope. It is the test that shows whether a supply recovers from a load step cleanly or rings, and the slope matters because a supply can pass a slow step and fail a fast one.
Battery mode discharges the pack at a set current to a cut-off voltage, integrating the current over time to report capacity, and recording internal resistance and a discharge curve along the way.
How to select the right programmable DC electronic load
The three ratings apply together, and the lowest one decides. A 48 V supply at 100 A is 4.8 kW, which no model here can sink; a 1500 W unit reaches only about 31 A at 48 V. Starting from the power rather than from the current avoids specifying an instrument that cannot run the test.
The second question is voltage. A 500 V model costs current for the same power, so it is the right choice only where the source has a high-voltage bus: a power-factor-corrected supply, an LED driver or a piece of equipment with a 400 V DC link.
The third is the test function. Battery discharge, dynamic stepping, OCP and list testing are all built in, so the choice is about which are needed rather than about add-ons. A bench that only checks steady-state regulation does not need the battery function; one that qualifies chargers needs all of them.
The fourth is recording. RS232C is standard and the PC software is optional, so a bench that logs results to a computer has to specify the software or write its own commands against the SCPI set.
Measurement limitations and selection considerations
The power rating is not available at every voltage and current. It is the product of the two, and the instrument reaches its power limit before its voltage or current limit at the extremes of the range. The derating curve matters at the top of the current range, and the material states that 120 A or 240 A is reached only under defined cooling conditions while the curve itself is not supplied.
The load dissipates everything it sinks as heat. At 1500 W the bench has to be able to remove that heat, and a unit installed in a rack with other equipment may not reach its rating. The installation conditions are part of the specification, not an afterthought.
The leads between the load and the source carry the full current and drop voltage. At 120 A a metre of ordinary cable drops a significant fraction of a volt, which appears as an error in the voltage reading and as a limit on the current actually reached. Four-terminal sensing at the load terminals is the reason the sense pair exists.
Finally, the load tests the source, not the product it powers. A supply that holds its voltage into a programmed current can still fail in the application, and the load’s job is to characterise the supply so that the application test can be designed.
Every value below is taken from source documentation. Where a parameter is not stated in the available material it is marked as information required rather than estimated.
