The difference between short circuit, overload and undervoltage protection

Encyclopedia
09/21/2024

Short circuit protection


Short circuit protection means that when there is a short circuit fault in the circuit, the protection device can quickly cut off the power supply to prevent the equipment and line from being damaged by too much current. A short circuit is usually caused by the direct shorting of the wires in the circuit, resulting in a direct reflux of current without the load.


Peculiarity


  • High current: Short circuit will cause the current to increase sharply, usually far more than the normal working current.


  • Fast response: Short-circuit protection devices (such as circuit breakers, fuses) must cut off power in a very short time (milliseconds).


  • Protection objective: To prevent equipment and lines from being damaged by excessive current.


  • Protection equipment: Common protection equipment includes circuit breakers, fuses, etc.



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  • Home circuitry: Protects home circuitry from fire risks caused by short circuits.


  • Industrial equipment: Protect motors, transformers and other equipment from short-circuit damage.


Overload protection


Overload protection means that when the current in the circuit exceeds its rated current but does not reach the short-circuit level, the protection device can cut off the power supply in time to prevent the device from overheating and damage due to long-term overload operation.


Peculiarity


  • Long-term overload:The overload current is usually slightly higher than the rated current, but the duration is longer.


  • Delay response: Overload protection equipment (such as thermal relays, overload protectors) will cut off the power after a period of time to prevent instantaneous overload resulting in misoperation.


  • Protection objective: To prevent equipment from overheating and damage due to long-term overload operation.


  • Protection equipment: Common protection equipment includes thermal relays, overload protectors, etc.


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  • Motor protection: Protect the motor from overheating damage caused by overload operation for a long time.


  • Heating equipment: Protect the heating equipment from overheating and damage caused by overload operation.



Undervoltage protection


Undervoltage protection means that when the voltage in the circuit is lower than a certain predetermined value, the protection device can cut off the power supply to prevent abnormal work or damage caused by the device operating under low voltage.


Peculiarity


  • Low voltage: Undervoltage protection usually occurs when the voltage is below the minimum required voltage for normal operation of the equipment.


  • Delayed response: Undervoltage protection devices (such as undervoltage relays) will cut off power for a period of time after the voltage falls below a predetermined value.


  • Protection objective: To prevent abnormal operation or damage caused by equipment operating at low voltage.


  • Protection equipment: Common protection equipment includes undervoltage relay, undervoltage lock out device, etc.


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  • Motor protection: Prevent overheating and damage caused by starting or running the motor at low voltage.


  • Control system: Protects the control system from misoperation or damage caused by low voltage.


Encyclopedia

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