DC electronic load from TTi

The LD300 has maximum input levels of 80 A and 80 V, with a maximum power dissipation of 300 W at 40°C, rising to 360 W at 25°C. It is designed to have very low internal resistance, allowing operation at high currents with low voltage drop.

TTi claims that the low cost of the unit makes it a viable alternative to in-house constructed passive loads, particularly as it can be re-configured to suit future requirements.

Load conditions are displayed using high-accuracy 4-digit meters. The voltage of the source can be sensed either at the terminals for convenience or at the load for better accuracy. A current monitor output provides a voltage proportional to the current flowing, allowing the behaviour of a source to be viewed on an oscilloscope or external meter.

The unit offers five different operating modes: constant current, constant voltage, constant power, constant resistance and constant conductance. The value of the chosen constant parameter is set by 10-turn controls on the front panel. Alternatively, an external control voltage can also be used to set the level of the load. Any desired waveform can be applied, allowing complex load conditions to be simulated.

An internal transient generator can repeatedly switch the load between two different operating levels set on separate 10-turn controls. The frequency and duty cycle of the transients can be set over a wide range. The transients can also be initiated by an external logic signal. The transitions between the levels have a true linear slewing characteristic in all modes, with the slew rate adjustable over a wide range.

The LD300 is fully protected against excessive current, power dissipation or internal temperature, and minimises audible noise by automatically controlling the fan speed according to the power dissipation. The unit is housed in a compact case measuring 130 x 212 x 435 mm (half rack width, 3U height) with a weight of 6 kg.