Last Updated on October 22, 2023 by Kevin Chen
Probably you know about a circuit breaker. It is a protective device designed to protect circuits from the dangers of current overload. It is a device that you will have to install in every electric wiring project.
What about motor circuit protector? Well, it is also a protective device, but has slightly different features from a circuit breaker.
The purpose of this guide is to break down the differences between a motor circuit protector and a circuit breaker.
At the end of it, you will know which one to buy for your project, and what you should look out for when buying either a motor circuit protector or a circuit breaker.
Definition: Motor Circuit protector vs circuit breaker
To start us off, let’s define what these two electronic components are.
A Motor circuit protector (MCP) is a special type of circuit breaker that is specifically designed to protect electrical circuits that drive an electrical motor. They are also known as instantaneous trip (IT) circuit breakers and you are likely to find them in industrial set ups where motors are used to run machines.
Most Motor circuit protectors have the protection features of electrical fuses and they are strategically positioned on the starters of motors.
What is a circuit breaker?
A circuit breaker is a device that will automatically trip to prevent the normal flow of current in an electric circuit. It does this to prevent any serious damage on the electrical device or system as a whole.
Circuit breakers are positioned at strategic points of a circuits, like on the panel board that is directly connected to the mains electric line. They have a specific rating and in case the current from the mains exceeds that limit, the breaker will trip to cut off the electric supply to the load or appliances.
After the circuit breaker has tripped, you will have to manually reset it to its original position and the supply of the electric current will resume. Circuit breakers are used in both domestic and industrial applications.
How does a motor circuit protector work?
The working principle of a MCP is slightly similar to that of a typical circuit breaker. It also cuts off the power supply in case it detects a current overload. Just like a circuit breaker, the MCP comes with a predetermined current and will trip in case the power to the motor goes beyond the designated current.
The bimetallic strip of an MCP is super sensitive to the heat changes. The excessive supply of current will cause this bimetallic strip to heat up and bend. As it does so, it will activate the magnetic trip mechanism which will eventually disconnect power to the motor.
Just like in the case of a circuit breaker you will manually reset the MCP to its original position, only after you have corrected the cause of the current overload.
One of the differences between motor circuit protectors and circuit breakers is based on their tripping mechanism.
The tripping mechanism of the MCP combines both the thermal and magnetic elements. The device has a thermal element that is sensitive to heat generated due to the current overload. The magnetic element on the other hand will react due to the overcurrent caused by short circuit.
Also, the tripping mechanism of MCP gives a special allowance of inrush current generated when the motor starts. This allowance ensures that the protector does not cause a false tripping.
On the other hand, while the tripping mechanism of a circuit breaker comprises of thermal-magnetic elements, it is fast and super sensitive. It does not give any allowance and will trigger instant reaction to the circuit in case of an overcurrent.
However, modern CBs have microprocessors that monitor the level of current and can delay in case of a false overcurrent. In short, this tripping mechanism does not have a time-delay characteristic as we have seen in the motor circuit protector.
This is another area where typical circuit breakers differ with the MCPs. While circuit breakers come with different current ratings, they will always be lower than that of MCPs. This is mainly due to the fact that MCPs are designed to handle large current levels that drive motors.
Physical design and dimensions
MCPs are generally larger than the circuit breakers. This mainly stems from the fact that they are designed to handle large amounts of current.
Motor circuit protectors are also characterized with heavy duty construction. They feature extra layers of material that offer protection against vagaries of nature such as extreme temperature. This also means that they should be handled by professionals.
On the other hand, most circuit breakers are small and compact. They have simple designs and can be handled with ease. You only need to read the basic instructions to install them to the breaker panel.
What about the cost?
Well, it is obvious that MCPs are more expensive than circuit breakers. However, the cost may vary depending on the model and specifications of the individual device that you are buying. Always ensure that you buy from a reputable supplier to get the best prices.
At this point, you know the similarities and differences between a motor circuit protector and a circuit breaker.
You have a clue on which one is the perfect solution for your circuit.
MCP is designed for protecting the connected motors while circuit breakers give the normal circuits the required protection.
Both have the protection functionality but deliver it in different manners.
When it comes to buying motor circuit protectors and circuit breakers, ensure that you choose one that meets the technical requirements of your products. It should be compatible with your product.
Also, ensure that you buy from reputable electronic components suppliers. This way, you can be sure of ending up with high-quality products.
Otherwise, we at ICRFQ are always committed to supplying electronic components in China.
Whether you want motor circuit protectors or circuit breakers, just talk to us and we will get you what you want, even if you want to buy electronic components in China wholesale.
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