What function does a circuit breaker have?
Circuit breakers are an indispensable protective device in power systems and are widely used in households, industries and businesses. Its main function is to automatically cut off the current when an abnormality occurs in the circuit, thereby protecting equipment and personal safety. The following are the core functions and detailed analysis of circuit breakers.
1. Overload protection
When the current in the circuit exceeds the rated value, the circuit breaker will automatically trip to prevent the wire from overheating and causing a fire. Overloading is usually caused by having too many appliances connected or a device with too much power.
| Overload current multiple | Trip time |
|---|---|
| 1.13 times rated current | More than 1 hour |
| 1.45 times rated current | Within 1 hour |
| 3 times rated current | seconds to minutes |
2. Short circuit protection
A short circuit means that the current forms a loop directly without passing through the load, causing the current to increase sharply. Circuit breakers can cut off circuits in milliseconds to avoid equipment damage or fires.
| short circuit current | Trip time |
|---|---|
| 5 times rated current | Within 0.1 seconds |
| 10 times rated current | Within 0.01 seconds |
3. Leakage protection (leakage circuit breaker only)
When leakage occurs in the circuit (such as electric shock to the human body), the leakage circuit breaker will quickly cut off the power supply to protect personal safety. Usually the operating current is 30mA and the operating time is less than 0.1 seconds.
4. Manual control function
The circuit breaker can be used as a switch for the circuit. It can be opened and closed manually to control the on and off of the circuit to facilitate equipment maintenance or emergency power outage.
5. Isolation function
The circuit breaker can provide an obvious disconnection point in the open state to ensure that maintenance personnel are isolated from live parts and comply with safe operating regulations.
Types of circuit breakers and applicable scenarios
| Type | Features | Application scenarios |
|---|---|---|
| Miniature circuit breaker (MCB) | Miniaturization, overload/short circuit protection | Home and office power distribution |
| Molded case circuit breaker (MCCB) | Adjustable protection parameters, large capacity | Industrial power distribution, motor protection |
| Air circuit breaker (ACB) | Extra large current breaking capacity | Substations, large factories |
| Residual current circuit breaker (RCBO) | Integrated leakage protection function | Bathrooms, kitchens and other humid places |
How to choose the right circuit breaker?
Consider the following factors when selecting a circuit breaker:
1.Rated current: Should be slightly larger than the maximum operating current of the line. Common household specifications include 10A, 16A, 20A, etc.
2.Breaking capacity: Refers to the maximum short-circuit current that can be safely cut off. 4.5kA-6kA is commonly used in households and higher in industry.
3.Number of poles: Unipolar (control live wire), bipolar (live wire + neutral wire) or three-pole (three-phase electricity).
4.special needs: If leakage protection is required, choose the RCBO model.
Maintenance points of circuit breaker
1. Periodic testing: Press the "TEST" button on the leakage circuit breaker every month to check whether the function is normal.
2. Cleaning and maintenance: remove dust after power off and check whether the wiring is loose.
3. Replacement standards: If the circuit breaker trips frequently or the handle is loose, it should be replaced in time.
As the "guardian" of circuit safety, the correct selection and use of circuit breakers is directly related to electrical safety. With the development of smart homes, there are now smart circuit breakers that can be remotely controlled, further improving the convenience of power management.
check the details
check the details
en
