Understanding the Different Types of Low Voltage Circuit Breakers

Understanding the Different Types of Low Voltage Circuit Breakers

by Ohm Engineering Works | Oct 01, 2024 | Electric Company 

Circuit breakers are essential safety devices in electrical systems, designed to protect circuits from overloading, short circuits, and other electrical faults. In low voltage applications, various types of circuit breakers are used, depending on the system’s requirements. Below, we’ll explore four common types of low voltage circuit breakers and discuss how to select the right one for your needs.

1. Miniature Circuit Breaker (MCB)

The Miniature Circuit Breaker (MCB) is widely used in residential and commercial applications to handle small to medium electrical currents. They are typically installed in sub-panels to protect lighting circuits and socket outlets. MCBs can manage current ratings up to 125 amps, providing protection against overloads and short circuits.

Applications:

• Household circuits (lighting, outlets)

• Small commercial setups

• Low to medium power distribution

2. Moulded Case Circuit Breaker (MCCB)

For larger electrical loads, Moulded Case Circuit Breakers (MCCBs) are commonly used. MCCBs can handle up to 1600 amperes, making them suitable for industrial applications and circuits with larger equipment like motors. They provide protection from overloads, short circuits, and ground faults.

Applications:

• Industrial plants

• Main and sub-distribution boards

• High-power electrical systems

3. Air Circuit Breaker (ACB)

Air Circuit Breakers (ACBs) are designed for very high current loads, typically up to 6300 amperes. They are used in main distribution boards in industrial facilities to handle large-scale power distribution. ACBs are crucial for protecting circuits from high fault currents and ensuring safe operation in critical environments.

Applications:

• Large industrial facilities

• Main power distribution

• High-current electrical systems

4. Residual Current Circuit Breaker (RCCB/ELCB)

Residual Current Circuit Breakers (RCCBs), also known as Earth Leakage Circuit Breakers (ELCBs), are essential for personal safety. They detect ground faults and disconnect the circuit when a leakage current is detected, preventing electric shocks. RCCBs are rated for currents up to 100 amperes and are commonly used in residential and commercial setups to protect individuals from electrical hazards.

Applications:

• Residential buildings

• Commercial properties

• Safety-focused installations

How to Calculate the Right Circuit Breaker for Your System

Selecting the appropriate circuit breaker for your electrical system requires calculating the current load and considering a safety margin.

1. Calculate the Total Circuit Current

Use the formula:

I = P / (V × pf)

Where:

• I is the current (in amperes),

• P is the total power (in watts),

• V is the voltage (in volts),

• pf is the power factor.

This will give you the total current required for the circuit.

2. Choose a Breaker with an Adequate Rating

Select a circuit breaker with a nominal current rating higher than the calculated current. For instance, if your calculated current is 25 amps, you might select a 32-amp breaker to ensure the breaker handles normal fluctuations without tripping.

3. Add a Safety Factor

Add a safety factor of 20-25% to the calculated current to accommodate surges or temporary increases in load. This precaution helps avoid nuisance tripping while ensuring safe operation.

Summary of Common Circuit Breakers and Their Applications

• MCB: Up to 125 amps, ideal for residential and small commercial sub circuits.

• MCCB: Handles up to 1600 amps, suitable for larger industrial loads.

• ACB: Rated for up to 6300 amps, used in large industrial systems.

• RCCB: Protects against ground faults, with ratings up to 100 amps, ensuring personal safety.

Conclusion

Selecting the right circuit breaker for your low-voltage electrical system is critical to ensure both the safety and reliability of your setup. By understanding the different types of low voltage circuit breakers—such as MCBs, MCCBs, ACBs, and RCCBs—and knowing how to calculate the appropriate breaker size, you can protect your circuits from overloads, faults, and potential hazards. Choosing the right breaker not only enhances electrical safety but also ensures the long-term reliability of your equipment and installations.