Circuit Breakers & Fuses

FAQs

In electrical engineering, can molded case circuit breakers provide overcurrent protection for electrical equipment in electrical systems?

Yes, molded case circuit breakers (MCCBs) can provide overcurrent protection for electrical equipment in electrical systems, safeguarding against maximum fault current and short circuit current.

What is "voltage drop" in control circuits?

In control circuits, "voltage drop" refers to the reduction in voltage that occurs as electrical current flows through the resistance or impedance of the conductors and components within the circuit​.

Breakers vs Fuses 

Fuses

Fuses are safety devices that are intended to provide protection to both equipment and people in the event of a power surge or an overcurrent situation. A fuse can provide this protection by using a small piece of wire that is sacrificial, and is intended to burn up when too much current is passed through it. When this happens, the fuse eliminates the flow of electricity in that circuit until it is replaced. The size and type of wire that is used in the fuse will dictate how much current can pass through that individual fuse. So the main thing to remember is, when a fuse blows, it must be replaced and cannot be reused. 

Circuit breakers

Circuit breakers are intended to be reused after they are “tripped” during a power surge or an overcurrent situation. Much like fuses, circuit breakers are designed to trip at a certain current level. This is intended to protect both equipment and anyone in the area of that particular circuit. Circuit breakers can be found in just about any variation from single phase, low current applications to three phase, and high current applications.

As a general rule: fuses are more simplistic and reliable. They cost less initially and are better suited for individual circuit protection. However, they can create more cost over time with each use and may create hazards due to the exposed connection points. Whereas circuit breakers offer better branch circuit protection and do not need to be replaced after each use. They are more expensive initially and, because of their complexity, are more prone to failure over time.