Siemens Industry Online Support
Siemens AG
Entry type: FAQ Entry ID: 30550697, Entry date: 07/28/2008

Difference Between Overcurrent Protection and Overload Protection

  • Entry
  • Associated product(s)


What is the difference between overcurrent protection and overload protection?


Overcurrent protection is protection against excessive currents or current beyond the acceptable current rating of equipment. It generally operates instantly. Short circuit is a type of overcurrent. Magnetic circuit breakers, fuses and overcurrent relays are commonly used to provide overcurrent protection.

Overload protection is a protection against a running overcurrent that would cause overheating of the protected equipment. Hence, an overload is also type of overcurrent. Overload protection typically operates on an inverse time curve where the tripping time becomes less as the current increases. Overload relays as well as “slow blow” fuses are commonly used to provide overload protection.

Some devices provide both overcurrent and overload protection. A thermal-magnetic circuit breaker has both thermal (overload) and magnetic (overcurrent) elements. Both elements operate as described above. Likewise the dual element fuse has both instantaneous and inverse time characteristics in the same fuse providing both overcurrent and overload protection.


Security information
In order to protect technical infrastructures, systems, machines and networks against cyber threats, it is necessary to implement – and continuously maintain – a holistic, state-of-the-art IT security concept. Siemens’ products and solutions constitute one element of such a concept. For more information about cyber security, please visit
Rate entry
no rating
Requests and feedback
What do you want to do?
Note: The feedback always relates to the current entry / product. Your message will be forwarded to our technical editors working in the Online Support. In a few days, you will receive a response if your feedback requires one. If we have no further questions, you will not hear from us.