The meaning of the trip characteristic curve is different in different applications (current-trip time).
B characteristic is suitable for pure resistive load and low-inductance lighting circuit;
C characteristic is suitable for inductive load and high-sensitivity lighting circuit;
D characteristic is suitable for high inductive load and large inrush current power distribution system;
The K characteristic is suitable for motor protection and transformer power distribution systems;
Their thermal tripping characteristics and electromagnetic tripping characteristics are different. The number after the letter refers to the rated current.
If you want to have a deeper understanding, please refer to GB10963 instantaneous overload capacity, B: 2 times, C: 5 times, D: 10 times, the level III current limit requirements specified in the IEC60898 standard
Type B curve: Protect the load with small short-circuit current (protect the load with small short-circuit current). Tripping characteristics: Instantaneous tripping range (3～5) In.
Type C curve: Protection of conventional loads and power distribution cables (distribution protection) port tripping characteristics: instantaneous tripping range (5~10) In.
D-curve: Protect the impact load with large starting current (such as motors, transformers, etc.) (power protection) tripping characteristics: instantaneous tripping range (10~14) In.
For miniature circuit breakers, there are four types of magnetic tripping curve circuit breakers, the tripping curve A/B/C/D:
1. Type A tripping curve: The magnetic tripping current is (2-3) In, which is suitable for protecting semiconductor electronic circuits, measuring circuits with low-power power transformers, or systems with long lines and low currents;
2. Type B tripping curve: The magnetic tripping current is (3-5) In, which is suitable for protecting the household power distribution system, the protection of household appliances and personal safety protection; Author: Electrical Design Teacher Di 3. Type C tripping curve ：The magnetic tripping current is (5-10) In, which is suitable for protecting power distribution lines and lighting lines with higher on-current;
4. Type D tripping curve: The magnetic tripping current is (10-20) In, which is suitable for protecting equipment with high inrush current, such as transformers and solenoid valves.
A feature: 2 times the rated current, rarely used, generally used for semiconductor protection;
B feature: 2~3 times the rated current, generally used for secondary circuit protection on the transformer side;
C characteristic; 5~10 times the rated current, this characteristic is the most commonly used, generally used for building lighting, etc.