Electronic Loads have wide applications from production lines for cell phone chargers, cell phone batteries, electronic vehicle batteries, switching power supplies, linear power supplies, and LED drivers, to research institutes, automotive electronic, aeronautic and astronautic, maritime, solar cell and fuel cell, etc. test and measurement applications.

In this context, we will list some frequently asked questions about electronic loads.

Question:

The electronic load has no response and no display when it is turned on. What should I check?

Answer:

First, check if the plug is loose. Second, check whether the 110V/220V power supply toggle switch matches the power grid and check the power supply voltage of the power grid. At last, check the fuse for damage. If these items are normal, please contact us.

Question:

The test data is unstable, what is the reason?

Answer:

Currently, our electronic load is a DC electronic load, in addition to requiring the voltage and current to be unidirectional, the voltage ripple should not be too large. A large voltage ripple may cause the circuit to oscillate and not work. If the test data is unstable, it is necessary to distinguish whether the output of the power supply itself is unstable or whether the electronic load test mode is not applicable.
For the first case, try to connect the electronic load with a stable linear power supply to test whether it is normal; then connect an appropriate filter capacitor in parallel with the positive and negative electrodes of the electronic load to test. If it is a SEL8 series product, please try SHIT+▲ to use LED mode. For the second case, different power supply products have applicable test modes, please contact us for technical support.

Question:

Does the load support pc communication? What communication lines are there? Can the customer program control it himself?

Answer:

Saluki’s electronic loads support pc communication, and we provide general control software. There are three optional types of communication cables: M131 (RS232), M132 (RS485), and M133 (USB). The communication protocol adopts the industry-standard Modbus RTU protocol. If customers need to program and control themselves, please contact us for technical support.

Question:

When do you need to use the remote measurement function?

Answer:

The remote measurement function is used to compensate for voltage drops on the leads. If the test current is large, the voltage drop on the wire and the actual output voltage of the power supply are relatively large, it is recommended to use the remote measurement function. The remote measurement function requires an additional two compensation connection leads. For details, please refer to Remote Test Function in the manual.

Question:

How to calculate the precision of readback value?

Answer:

Taking the SEL711 as an example, the accuracy of the measured value in CC mode is ±0.03%+0.05%FS, assuming the actual current is 20A, and FS is expressed as the full-scale current value (current gear), then the accuracy of the measured value is ±0.03%×20+ 0.05%×30=±0.021A. That is, when the actual test current is 20A, the test error does not exceed ±0.021A.

Question:

Can electronic loads be used in series and parallel? Are there any usage restrictions?

Answer:

Electronic loads can be used in parallel, not in series. Since the voltage is the same when connected in parallel, it is recommended that the voltage range of the electronic load be the same to avoid damage to the electronic load due to misoperation. The CV mode cannot be used for parallel testing, except for a few customized special models.

Question:

Which common power supply categories are the working modes of electronic loads suitable for?

Answer:

Generally speaking, the constant voltage source can be tested in CC mode, and the constant current source can be tested in CV mode. Batteries and super capacitors are tested in CC mode; chargers use CC and CV modes; LED drive power uses CV and CR modes; solar photovoltaic modules use CV mode; hydrogen fuel cells and thermoelectric systems generally use CC and CR modes.

Question:

Can the electronic load test storage battery use CV mode? What should be paid attention to when using?

Answer:

No, you can’t use the CV mode. Storage batteries, as the name implies, can store electrical energy and provide a steady stream of electrical energy within a certain period of time. The CV mode of the electronic load is to achieve the purpose of constant voltage by adjusting the loop current. The instantaneous power of the battery has far exceeded the power upper limit of the electronic load. Using CV mode with a storage battery without a protective plate may damage the electronic load. When in use, wire correctly when the electronic load is OFF, and test using CC mode.

Question:

How to use the external trigger function of electronic loads?

Answer:

There are trigger terminals on the rear panel of the electronic load, which are divided into TRI trigger input and TRQ trigger output.

TRI is a passive trigger mode, short-circuit and then disconnect GND to complete a trigger operation. TRI can trigger ON/OFF switch, or as a trigger function for LIST and AUTOTEST. TRQ can be used as the trigger output function of AUTOTEST to indicate the test result (PASS or FAIL); there is no voltage when it is not output, and there is 5V voltage after the trigger output, and it can be connected to an optocoupler or relay to output an alarm.

Question:

The electronic load can be used to test solar module products, how to use it?

Answer:

The test of solar modules can be carried out with the CV mode. We have a paid solar module test system. The test items include maximum output power (Pmax); current value at maximum power (Imax), voltage value (Vmax), short circuit current (Isc), open circuit voltage (Voc), filling factor (FF), series resistance (Rs), parallel resistance (Rsh), irradiance (E), cell area (S), current density (Jsc) and conversion efficiency (η). Contact us for details.