In modern power system, circuit breakers and surge protector are indispensable protective devices. However, when designing a distribution system or selecting a device, many customers often ask: is it necessary to have a surge protectors now that a circuit breakers is in place?
As a professional manufacturer of surge protector, we believe that understanding the difference is critical to improving the safety of electrical systems and the reliability of equipment.
What is a circuit breaker?
Circuit breakers are switching devices used to protect circuits from overload and short-circuit failures.
When the circuit current exceeds the rated value, the circuit breaker will automatically disconnect the circuit, preventing cable from overheating, equipment damage or even fire.
Circuit breakers address two main types of problems:
Overload current
Short circuit current
Therefore, the core task of circuit breaker is to protect the safety of circuit and distribution system.
What is a surge protector?
Surge protector (SPD) is a protective device used to limit transient overvoltage and discharge surge currents.
Lightning strike, power grid switching, large motor startup, transformer switch, etc., will produce transient high-voltage pulse. Although these voltage surges are extremely short in duration, they are powerful enough to damage internal components of electronic devices.
SPD protects the device from overvoltage surges by rapidly directing the overvoltage surge current into the grounding system.
Its main protection targets include:
PLC control system
Server and data center equipment
Communications base station equipment
Video surveillance systems
Photovoltaic inverters
Industrial automation equipment
Smart distribution equipment;
Core differences between circuit breakers and a surge protector:
1. Different Protected Objects
Circuit breaker main protection:
Cable
Distribution lines
Electricity distribution equipment
Surge savers mainly protect:
Precision electronics
Control system
Communications equipment
2.They deal with different types of glitches
Circuit breaker treatment:
Overload
Short circuit
Surge saver treatment:
Lightning overvoltage
Operating overvoltage
Induced surges
3.Different response times
The response time of circuit breakers is usually within milliseconds.
Surge savers usually response time in nanoseconds.
Due to the extremely short lifespan of lightning surges, circuit breakers often don't have enough time to operate and therefore can't replace SPD protection.
4. Different working principles
Circuit breaker disconnects the circuit through a a mechanical tripping mechanism.
SPDS (Susceptible Power Distribution Devices) rapidly conduct electricity through components such as inverters and gas discharge tubes, discharging surging energy into grounding system.
Why is SPD still needed even with circuit breaker?
This is one of the most overlooked problems in many engineering projects.
For example:
A nearby lightning strike can generate thousands or even tens of thousands of volts.
Although the surge is only a few microseconds, it is enough to break us:
PLC input module
Communications interface
Power supply Module
Control board
Due to the short duration of current, circuit breaker cannot detect and interrupt faults in a timely manner.
As a result:
The circuit breaker doesn't jump, but the equipment was damaged.
As a result, an increasing number of data centers, industrial automation systems, photovoltaic power stations and communications base stations are using solid-state drives as standard equipment.
Why a circuit breaker before SPD?
Many users see SPD itself as a protective device that doesn't require additional circuit breaker.
In fact, short circuits can occur when SPD fails due to long-term aging or excessive surge impact.
At this point, it is necessary to use the front circuit breaker or backup protection device to interrupt off the fault current in time to prevent equipment damage and safety accidents.
Therefore, a complete surge protection plan usually includes:
Grid → Circuit breaker → SPD → Load equipment
This structure prevents overloading and short circuits, as well as lightning surges.
How to choose the right SPD?
In selecting SPD, it is recommended to focus on the following parameters:
Maximum continuous operating voltage (Uc)
Nominal discharge current (in inches)
Maximum discharge current (Imax)
Voltage protection level (above)
Response time
Installation environment
At the same time, type 1, type 2 or type 3 surge protectors should be selected according to the level of lightning protection in the building and the structure of the distribution system.
Conclusion:
While circuit breakers and surge protectors are electrical, their roles are completely different. Circuit breakers are responsible for preventing overload and short-circuit failures, and surge protectors are responsible for preventing lightning strikes and transient overvoltages. The two are complementary and indispensable.
With the rapid development of industrial automation, smart grid, data centers and new energy system, electronic equipment demands more and more power supply quality and security. Proper configuration of circuit breakers and SPD can not only improve system reliability, but also reduce equipment failure rate and maintenance cost, and create more long-term value for enterprises.