The use of molded case circuit breakers varies widely. In this overview of some of the most common MCCB application examples, you’ll get a better understanding of how these breakers are used in residential, commercial, and industrial power systems.
What is MCCB and Its Working?
Before diving into the application of MCCB circuit breakers, let’s quickly see what MCCB is and how it works. A molded case circuit breaker (MCCB) is a type of electrical protective device that trips in response to an overload or other overcurrent situation such as short circuiting.
To enable that, the breaker is equipped with both thermal and magnetic fault detection mechanisms. The thermal detection system senses overloads while the magnetic mechanism senses and responds to, short circuits.
Some types of MCCB breakers will also often incorporate earth leakage current detection systems. An MCCB with this feature will monitor for stray current flowing to the ground and trip when it reaches a certain level.
MCCB application ranges from protecting feeder circuits to shielding the motors of industrial machines. In the following examples, we have listed (and explained) some of the 6 most popular situations where the application of MCCB circuit breakers is necessary or beneficial.
MCCB for Home
In residential homes, MCCB breakers are used to protect the various circuits throughout the house such as HVAC systems and lighting fixtures. The breakers are typically located in the main service panel and should be sized to meet the requirements the home system.
The MCCB for home wiring mainly ranges from 100 – 200 Amps. Most residential load centers come with either one or two-pole breakers, although three and four pole units are also available for applications that require extra protection.
Because molded circuit breakers are mostly rated for relatively high current systems, an MCCB for home systems is normally used in situations that exceed the capabilities of conventional MCB or mini circuit breakers.
MCCB for Motor Protection
In motor-driven applications, it is often necessary to protect the motor from overloads and other hazardous situations with an appropriately rated MCCB. For single phase motors, a one 2-pole MCCB breaker is usually sufficient while three and four pole units are needed for three phase systems.
In this MCCB application, it’s important to select an MCCB with a suitable rating for both the motor and the circuit. The breaker should be sized so that it trips in the event of an overload or short circuit, but allow normal current flow during start-up and running conditions.
A generator MCCB is used to protect the generator and connected circuits from faults that may occur in the system. This type of breaker is usually rated in relation to the generator output current to ensure that it can withstand higher than normal faults.
In order to properly protect the various circuits, it’s important to install a generator MCCB that has been designed with this application in mind. To do so, you should select one whose a trip range or trip class corresponds to the generator’s requirement for short circuit withstand delay.
In applications where multiple circuits are fed from a single panel board, it becomes important to protect the feeder circuit with an MCCB. The use of MCCB in electrical systems of this kind helps prevent overloads or other hazardous conditions from affecting all of the circuits downstream.
Just like in the motor protection and generator applications, a feeder MCCB is sized to match the current rating of the feeder circuit. That means the breaker should be rated for the full load current of the circuit, which is usually determined by the current of voltage carries by the feeder conductors.
MCCB for DC Applications
An MCCB for DC applications is similar to an AC MCCB, except that it must be specifically built for use with DC voltage. Some of the more common DC applications where an MCCB may be used include photovoltaic systems, battery banks, and electric vehicle chargers.
One of the reasons to use a DC MCCB is that DC arcs are more difficult to extinguish than AC arcs, making them more dangerous. An MCCB circuit breaker helps protect against these dangerous arcing conditions by providing a more effective method of interruption.
MCCB for Welding Machine
This MCCB application is necessitated by the fact that welding machines require higher levels of protection than the conventional MCB circuit breaker would provide. This is because the welding machine’s current ratings are typically higher, so it requires a larger MCCB breaker to handle the load without tripping unnecessarily.
An MCCB for welding machine protection should be sized to the machine’s rated current and should have a trip range that is suitable for the device. Additionally, it’s important to make sure the MCCB is compatible with the welding machine’s voltage.
MCCB for Capacitor Bank
The application of MCCB circuit breakers goes beyond the conventional power circuits and electrical equipment. It’s also possible to use MCCB breakers to protect capacitor banks and other components that store energy.
Capacitor banks are commonly used in power factor correction applications and can provide a great deal of energy that needs to be managed safely. An MCCB protection device is the ideal tool for this job, as it allows you to quickly shut off any excess current before further damage or injury occurs.
When using an MCCB for capacitor bank protection, it’s recommended to select one that is designed for the specific system. This type of breaker will be able to withstand the large current draw that occurs when a capacitor bank is initially energized or discharged.
MCCB application settings vary from home wiring to industrial operations, and the selection of an MCCB should be based on the specific application. It’s recommended, therefore, to choose an MCCB that is rated for the voltage, current, and type of protection needed in order to ensure safe operation. This is because molded case circuit breakers come in a wide range of ratings or trip range and features to suit different protection requirements.
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