How To Choose A Circuit Breaker?

Posted by Perry Harper on March 29th, 2021

You can't buy a machine with a damaged case, with visible cracks, chips. It is also impossible to use a machine with a rating greater than the current one. First of all, the circuit breaker is selected based on the characteristics of your wiring and load.

The way to choose a circuit breaker

Automatic machines have to be purchased at specialized stores and well-known circuit breaker manufacturers. The cost of such a machine is of course higher, but it will go into the background when it comes to your safety. The choice of the circuit breaker is carried out by criteria such as:

The number of masts of the engine;

The length of the operating voltage ;

The maximum permissible operating current of the switch;

Breaking capacity;

Engine selectivity.

Determination of the number of engine poles

The choice of the number of automatons depends on the type of power grid. With a single-phase network the  number of poles can be 1 or 2, that is, the automaton can be single or multiple poles.

Single pole connection and three pole circuit breaker

In everyday life, with a single-phase network at the input and for individual machines, a single mast structure is used. Bipolar machines can be used at the input. In this case, the operating probability of a double pole automaton is doubled, the three-phase network uses automata on three or four poles. When you wish to find out details about circuit breaker, you must check here at EletronicoBlog.com website.

Rated engine voltage

The plastic case of the machine contains information about its characteristics and its operating voltage.

The consumed current of the electric circuit must not exceed the rated current of the automatic machine, at the same time the rated current of the automatic machine should not be more than the rated current for the wiring section of the power cable. The over current from the circuit breaker must be 1.45 times less than the maximum rated current in the wire.

Circuit Breaker Selectivity

The circuit breaker selectivity value indicates the ability of the circuit breaker to disconnect only those parts of the electrical circuit where short circuit or overload occurs. In order for the machine to have good selectivity, you need to make the right choice according to the parameters and class of the machine.

An example of the selectivity of a circuit breaker

For good selectivity, the input automaton should have a rated current value greater than the automata in the group, but not exceeding the maximum current of the mains cable. Within the group, the automata are selected according to the load flow of this group. That is, if there is a short circuit in the kitchen, the kitchen socket panel will automatically turn off, and not the lighting.

The thermal load of several machines is installed sequentially

When the circuit breaker is located on the electric panel successively, the temperature of the automata will increase and the nominal current of the automaton will decrease by the correction factor.

Calculation of short circuit current is necessary for the correct selection and removal of protective equipment. Short circuit current occurs when the phase carrier parts of the phases are connected to each other or to an electrical receiver that is earthed in the circuit with the neutral wire and the neutral wire off.

Selection of circuit breakers

Circuit breakers are   selected mainly at nominal values of voltage and current. Then, the setpoint currents of the thermal and electromagnetic discharge are determined.

Automatic machine buffer thermal protects electrical installations from prolonged overcurrent. The current setting of the thermal release is assumed to be 15-20% more than the operating current:

Electromagnetic automatic travel machine unit protects electrical installations from short circuit. The current electromagnetic discharge setting is determined from the following considerations: the machine should not operate from the starting current of the electric installation motor we launch.

The selected circuit breaker is checked for sensitivity and breaking capacity. Automata with rated current up to 100 A must operate under these conditions.

Circuit Breaker Selection Criteria

The main indicators referred to in choosing a machine are:

Number of poles;

Rated voltage;

Maximum operating current;

Breaking capacity (short circuit current).

Number of poles

The number of poles is determined by the number of network phases. For installation in single-phase networks, use single pole or double pole. For three-phase networks, apply three and four poles (network system) neutral TN-S grounding In the residential sector, single or double mast machines are usually used.