The difference between thermal magnetic and electromagnetic types of molded case circuit breakers

07 Apr 2024

The main differences between thermal magnetic circuit breakers and electromagnetic circuit breakers are reflected in triggering time, protection sensitivity, overload resistance, working principle, and applicable scenarios.

The rmomagnetic

Electronic

Here is a detailed introduction:

a. Trigger time. The triggering time of electromagnetic circuit breakers is relatively short, usually only a few tens of milliseconds, and is suitable for situations where the circuit current increases sharply in a short period of time; The triggering time of thermal magnetic circuit breakers is relatively long, requiring several seconds or more, and is suitable for situations where the circuit current exceeds the operating limit for a long time.

b. Protection sensitivity. Electromagnetic circuit breakers have high protection sensitivity and can operate as long as the current exceeds the rated value, providing good short-circuit protection; The sensitivity of thermal magnetic circuit breakers is relatively low, requiring a current exceeding the rated value and lasting for a certain period of time before they can operate, and cannot provide good short-circuit protection.

c. Anti overload capability. The overload resistance of thermal magnetic circuit breakers is stronger than that of electromagnetic circuit breakers, and they can withstand long-term overload currents, making them suitable for circuits that require long-term continuous operation; Electromagnetic circuit breakers have relatively poor overload resistance and are easily affected by short-term overload currents, making themsuitable for circuits that require short-term operation.

d. Working principle. Electromagnetic circuit breakers rely on electromagnets to achieve circuit breaker protection. When the current exceeds the set current value, the electromagnet generates a magnetic field, causing the contact to detach from the circuit breaker base, achieving circuit breaker protection; The thermal magnetic circuit breaker combines electromagnetic and thermal effects, and the thermal magnetic element detects the magnitude of the load current and overload current, generating heat. When the current is overloaded, the heat causes the thermal fuse inside the thermal magnetic element to melt, achieving overload protection.

e. Applicable scenarios. Thermal magnetic circuit breakers are suitable for low voltage and high current scenarios, such as household electricity, industrial production, etc; Electromagnetic circuit breakers are suitable for medium and high voltage scenarios, such as power systems, transformers, motors, etc.

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