engineering

Programmable load

Programmable load is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Programmable load rather than just read about it. In short: A programmable load is a type of test equipment or instrument which emulates DC or AC resistance loads normally required to perform functional tests of batteries, power supplies or solar cells. By virtue of being programmable, tests like load regulation, battery discharge curve measurement and transient tests can be fully automated and load changes for these tests can be made without introducing switching transient…

Key takeaways

Programmable load belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Programmable load to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Programmable load from memory before moving on to harder problems.

Reference excerpt

A programmable load is a type of test equipment or instrument which emulates DC or AC resistance loads normally required to perform functional tests of batteries, power supplies or solar cells. By virtue of being programmable, tests like load regulation, battery discharge curve measurement and transient tests can be fully automated and load changes for these tests can be made without introducing switching transient that might change the measurement or operation of the power source under test.

Implementation Programmable loads most commonly use one transistor/FET, or an array of parallel connected transistors/FETs for more current handling, to act as a variable resistor. Internal circuitry in the equipment monitors the actual current through the transistor/FET, compares it to a user-programmed desired current, and through an error amplifier changes the drive voltage to the transistor/FET to dynamically change its resistance. This 'negative feedback' results in the actual current always matching the programmed desired current, regardless of other changes in the supplied voltage or other variables. Of course, if the power source is not able to supply the desired amount of current, the DC load equipment cannot furnish the difference; it can restrict current to a level, but it cannot boost current to a higher level. Most commercial DC loads are equipped with microprocessor front end circuits that allow the user to not only program a desired current through the load ('constant current' or CC), but the user can alternatively program the load to have a constant resistance (CR) or constant power dissipation (CP).

References

Worked examples

Example 1 — a first encounter with Programmable load

Start with the simplest possible case. Write down what Programmable load claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Programmable load before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Programmable load ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Programmable load

In research: Programmable load appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Programmable load in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Programmable load is common in secondary-school and first-year university syllabi. It links to neighbouring topics Electronic engineering, Electronic test equipment, Hardware testing, so understanding it makes those chapters shorter.
In everyday life: Look for Programmable load outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Programmable load in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Programmable load means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Programmable load out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Programmable load in simple terms?

Why does Programmable load matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Programmable load?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Programmable load.