Circuit breaker, full name automatic air circuit breaker, also known as air switch, is a commonly used low-voltage protection electrical appliance, which can realize short-circuit, overload and other functions.

Circuit breakers are used as main power protection switches or branch line protection switches in household power supply.

When a short circuit or overload occurs in residential wiring or household appliances, it can automatically trip and cut off the power supply, thereby effectively protecting these equipment from damage or preventing accidents from expanding;

Households generally use two-pole (ie 2P) circuit breakers for main power protection, and single-pole (1P) for branch protection;

If the rated current of the circuit breaker is selected too small, the circuit breaker is likely to trip frequently and cause unnecessary power outages. If the selection is too large, the expected protection effect will not be achieved. Therefore, the correct selection of the rated capacity current of the home improvement circuit breaker is very important. important.

The general miniature circuit breaker specifications are mainly divided into 6A, 10A, 16A, 20A, 25A, 32A, 40A, 50A, 63A, 80A, 100A, etc. according to the rated current; then how does the average family choose or check the total value of the total load current?

1. First, calculate the value of each branch current

①For purely resistive loads, such as light bulbs, electric heaters, etc., the indicated power is directly divided by the voltage.

Formula I=power/220v;

For example, a 20w bulb, the branch current I=20W/220=0.09A

Electric fans, electric irons, electric blankets, water heaters, electric water heaters, electric heaters, rice cookers, electric frying pans, vacuum cleaners, air conditioners, etc. are resistive loads. [How to choose household circuit breaker and air switch? 】

②Inductive loads, such as fluorescent lights, televisions, washing machines, etc. The calculation is slightly complicated, and the power consumption should be considered, and the specific calculation should also consider the power factor. To facilitate the estimation, the author gives a simple calculation method, that is, the general inductive load. It is sufficient to indicate that the calculated power of the load is doubled. For example, indicate that the branch current of a 20W fluorescent lamp is I=20W/220v=0.09A, which is doubled to 0.09A*2=0.18A (than the exact calculated value of 0.15A , 0.03A more)

Fluorescent lamps, refrigerators, TVs, etc. are classified as perceptual

2. The total load current is the sum of each branch current

Knowing the branch current and total current, you can select the specifications of the branch circuit breaker and the main switch circuit breaker, the main fuse, the main electric meter and the branch wires, or check whether the specifications of the designed electrical components meet the safety requirements;

In order to ensure safety and reliability, the rated working current of electrical components should generally be greater than 2 times the required maximum load current; in addition, when designing and selecting electrical components, the possibility of future increase in electrical load should be considered, so as to reserve for future requirements. There is margin.