Circuit Breakers

What is the role of a circuit breaker?

The thermal-magnetic circuit breaker plays an essential role in protecting an electrical installation. It protects both the equipment to which it is connected and all the electrical circuits and cables in the installation. 

Why is the tripping curve of a circuit breaker important?

If the defined current is surpassed, the circuit breaker must trip to prevent damage to the electrical installation and equipment. The important consideration is therefore the value of the current that the protection device can withstand for a time. The trip curve sets the circuit-breaker tripping threshold and varies according to the equipment to be supplied. This indicator should not be overlooked when purchasing a circuit breaker.

The standard NF EN 60898 defines 5 tripping curves:

• B Curve: the circuit breaker trips between 3-5 times the full load current. This curve is mainly used for electrical circuits with long cable runs. 
• Curve C: the circuit breaker trips between 5-10 times the full load current. This is the curve most commonly used to protect domestic installations. 
• Curve D and K: the circuit breaker trips between 10-14 times the full load current. Mainly used to protect circuits and cables with very high current peaks when powered up, such as motors, heat pumps, and ventilation units. 
• Curve Z: the circuit breaker trips between 2.4-3.6 times full load current. For protecting electronic circuits and drives.

What are the 3 types of circuit breaker devices?

There are 3 main families of circuit breakers on the market and all can be found here at One-Elec:

• The main circuit breaker, a large circuit breaker, has a crucial role in the electrical system by disconnecting power to the entire panel and shutting off power to the entire house. This is the starting point for the electrical circuit, separating the private installation from the public network.
• Circuit breakers, including MCBs, are the most numerous in the electrical panel, as they protect each electrical circuit. 
• Differential circuit breakers or RCDs are placed upstream of circuit breakers and their primary function is to protect people from the risk of electrocution from current leakage.
  

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Schneider Electric, Legrand, Hager and ABB thermal-magnetic circuit breakers at One-Elec

One-Elec's online catalogue features circuit breaker brands that are known and trusted for their quality, reliability, and easy installation. 

From 2 to 3200 A, 1-pole, 2-pole, 3-pole and 4-pole devices, with trip curves B, C, D, K or Z, the wide range of products on offer meets all the needs of the residential, commercial and industrial sectors.

Why do we call them thermal-magnetic circuit breakers?

This type of circuit breaker uses 2 technologies:

• Magnetic technology, which protects against short circuits. The circuit breaker, fitted with an electromagnetic coil, reacts instantly (20 ms) to a very sudden increase in current (short circuit current > 3 to 10  times full load current.). It converts this increase into mechanical energy, opening the circuit and tripping the circuit breaker.

• Thermal technology protects against electrical overloads. The circuit breaker, fitted with a bimetallic strip, deforms when heated by a low over current, (1.2 to 5 times the full load current load) lasting between 30 seconds and 10 minutes. It transforms the increase in current into mechanical displacement, in this case opening the circuit and tripping the circuit-breaker.

Resi9 and Acti9, Schneider Electric's flagship circuit-breaker ranges

One-Elec offers electricians the 2 most popular circuit breaker ranges on the market: Resi9 for the residential sector up to 63 A and Acti9 to meet other needs up to 125 A.

One-Elec's range of commercial and industrial circuit breakers

One-Elec is developing a range of medium and high-power circuit breakers for currents above 125 A and up to 3200 A. A low-voltage solution addresses the demand for compact circuit breakers with hyper-concentrated performance.