Constant resistance is an operating mode where a load maintains a fixed resistance value while voltage and current vary according to Ohm’s Law.

In a constant resistance load:

• Resistance remains fixed
• Current changes proportionally with voltage
• Power changes depending on both voltage and current

Constant resistance operation is commonly used in:

• Electronic loads
• Power supply testing
• Battery testing
• Load simulation applications

How Constant Resistance Works

A constant resistance load behaves similarly to a physical resistor.

The relationship between voltage, current and resistance follows Ohm’s Law:

I=RV​

Where:

• $I$I = Current
• $V$V = Voltage
• $R$R = Resistance

If the voltage increases while resistance remains fixed, the current increases proportionally.

Example of Constant Resistance

For example:

• A 10Ω constant resistance load connected to 10V will draw 1A
• If the voltage increases to 20V, the current increases to 2A

The resistance remains constant throughout.

Constant Resistance vs Constant Current

Constant resistance and constant current are different operating modes.

Constant Resistance (CR)

• Resistance stays fixed
• Current changes with voltage

Constant Current (CC)

• Current stays fixed
• Resistance changes dynamically

Constant Resistance vs Constant Power

In constant resistance mode:

• Power changes as voltage changes

In constant power mode:

• The load adjusts current automatically to maintain fixed power

Constant Resistance in Electronic Loads

Electronic loads often include constant resistance mode to simulate real-world resistive loads.

This is useful for testing:

• Power supplies
• DC-DC converters
• Batteries
• Chargers
• Voltage regulators

The load dynamically adjusts current draw to maintain the programmed resistance value.

Why Constant Resistance Is Useful

Constant resistance mode provides realistic testing conditions because many real electrical loads naturally behave resistively.

Examples include:

• Heating elements
• Incandescent lamps
• Basic resistive circuits

It helps engineers evaluate:

• Voltage stability
• Current capability
• Regulation performance

Constant Resistance and Power Dissipation

As voltage increases across a constant resistance load:

• Current increases
• Power dissipation increases rapidly

Power follows the equation:

P=RV2​

This means even small voltage increases can produce significantly higher power dissipation.

Applications of Constant Resistance Mode

Constant resistance mode is commonly used in:

• Electronic load testing
• Battery discharge testing
• Power supply evaluation
• Circuit simulation
• Laboratory testing
• Educational electronics

It is especially useful where predictable resistive behaviour is required.

Advantages of Constant Resistance Testing

Benefits include:

• Simple load simulation
• Realistic resistive behaviour
• Stable testing conditions
• Easy comparison between systems

It is also useful for evaluating:

• Voltage regulation
• Output stability
• Thermal performance

People Also Ask

What is constant resistance?

Constant resistance means a load maintains a fixed resistance value while current changes with voltage.

How does constant resistance work?

The load follows Ohm’s Law, where current changes proportionally as voltage changes while resistance remains fixed.

What is constant resistance mode in an electronic load?

Constant resistance mode allows the electronic load to behave like a fixed resistor during testing.

What is the difference between constant current and constant resistance?

Constant current keeps current fixed, while constant resistance keeps resistance fixed.

Why is constant resistance important in testing?

It helps simulate realistic resistive loads when evaluating power supplies and electronic systems.