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Detailed Working and Components of Circuit Breakers

by Manan Shah - 30 May 2022, Monday 76 Views Like (0)
Detailed Working and Components of Circuit Breakers

Circuit breakers are unique safety devices that detect excessive current flow in circuits and open the circuit as soon as the current flow exceeds a certain threshold. Because the circuit breaker does not function alone, but rather with a relay, these are incredibly beneficial in safeguarding the entire ship from serious electrical threats. When the relay detects a malfunction and sends a signal to the circuit breaker, the circuit breaker trips, safeguarding the entire circuit.

Many times in the ship, there are unexpected electrical failures that, if not treated immediately, can cause substantial damage to the electrical infrastructure of the location, as well as severe accidents and fires that can have fatal consequences. Several safety methods are employed in electrical installations to prevent these circumstances, including the fuse, the surge arrester, and the circuit breaker, the latter being the core component of a well-protected electrical system. Since ships are in the sea for most part of the year, it becomes extremely important to safeguard the entire region from electrical hazards as no help would be available if major accidents happen onboard.

What exactly does a circuit breaker do in ships

A ship's primary electrical circuit is made up of a number of smaller circuits.

The electric current is controlled within safe limits or voltage limitations under typical circumstances. This is required because an excess of electric charge might harm the structure's various components. However, the electrical charge can occasionally exceed what a circuit can take for different reasons, causing damage to the circuit and the devices and equipment linked to it, as well as igniting a fire.

Fire in an onboard ship or damage to vital devices in a ship can prove to be extremely dangerous. Circuit breakers' primary job is to continually "check" that the electrical charge does not exceed the safety limits and, if it does, to immediately shut down the electrical circuit to prevent accidents.

Basic design of a circuit breaker

Most of the circuit breakers typically have almost the same components in their design and below are those components


The frame is the circuit breaker's exterior shell, which is commonly formed of moulded insulating materials. If a danger arises, this protects the internal components as well as everything on the outside of the breaker.


The terminal is a metal block with a bolt protruding from the exterior. Here are linked the wires that transport electrical current from the power source, via the breaker, and to a load.


The trip unit is attached to the lever (switch), which permits a breaker to be turned on or off. When a circuit breaker trips, the lever will be in the middle, allowing you to readily determine which one requires attention.


The contacts are two metal parts that move to close (interrupt) or open (close) the circuit. The actuator mechanism is connected to one contact, while the main panel is connected to the other.

Actuator Mechanism

The circuit breaker's actuator mechanism is a metal arm. The lever is attached to one end, while the contact is linked to the other. When the lever is flipped, the actuator mechanism pushes or pulls the contacts together.

Trip Unit

In the case of an overload, short circuit, or malfunction, a trip unit notifies the breaker when to trip automatically.

Working of circuit breakers

Circuit breakers are made up of pairs of fixed and movable metallic contacts, as well as an operational coil, on the inside. Under normal circumstances when the circuit is closed, these contacts are in contact with one another, allowing electric current to flow. The mechanical pressure applied by another device such as a spring or compressed air keeps these moving contacts together. The potential energy stored in the above mentioned pressure mechanism allows for this pressure on the moving contacts. When the electrical circuit is overloaded, the operational coil is charged with energy, and a plunger attached to the moving contact mechanism allows the energy stored in this mechanism to be released, allowing the moving contacts to separate as well.

The circuit within the circuit breaker opens when the moving contacts separate, preventing the flow of electricity and safeguarding the system from further harm. A plasma discharge known as arc happens when electrical current travels through an air gap from an energised component to a neutral component. Arcing may occur in domestic electrical wiring, as well as within circuit breakers during operation, causing damage and fires if the arc is not regulated. As a result, the mechanism of circuit breakers is to avoid or regulate the creation of these electric arcs as much as feasible.

 When a circuit breaker's lever is turned to the "on '' position, electricity may freely flow from the power source (usually the electrical panel or main), via the trip unit, contacts, and out the upper terminal to power the circuit's loads. In an incident such as an overload, the bi-metallic strip of a thermal magnetic trip unit overheats, forcing it to bend and open the circuit (automatically cutting off power). The electromagnetic force causes the contacts within the circuit breaker to separate during a defect or short circuit, tripping the breaker and cutting off the electricity to the circuit with the problem.

Common causes of tripping of circuit Breakers

In ships, there might be various reasons for the tripping of circuit breakers which are discussed below

  • The most prevalent cause of circuit breakers tripping is overloaded circuits. This occurs when there is too much on a single circuit and everything demands more power than the circuit can safely handle.The most prevalent cause of circuit breakers tripping is overloaded circuits. This occurs when there is too much on a single circuit and everything demands more power than the circuit can safely handle.
  • When a "hot" and "neutral" wire come into contact with one another, a short circuit occurs. This is potentially harmful and creates a lot of heat, tripping a circuit breaker.
  • Ground fault surges occur when a "hot" comes into touch with a ground or the metal on a box linked to a ground, similar to a short. This results in a rush of power that exceeds the circuit's safe capacity, tripping the breaker.