The difference between short circuit, overload and undervoltage protection

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.

Apply

• 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.

Apply

• 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.

Apply

• 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.