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Relay protection and overcurrent protection

time:2021/12/3   source:华天电力  reading:454 time

Relay protection is a very important test in power system testing. It is an important measure that can detect faults or abnormal conditions that occur in the power system, thereby issuing an alarm signal, or directly isolating and removing the fault. The instrument generally used in relay protection work is a microcomputer relay protection tester.


Because relays with contacts were mainly used to protect the power system and its components (generators, transformers, transmission lines, etc.) from damage during its development, it is also called relay protection.


Protection Relay Test Set.png

There are also many types of relay protection, including current protection, distance protection, differential protection, pilot protection, gas protection, etc. What does overcurrent protection look like?


Overcurrent protection is a protection method that causes the protection device to operate when the current exceeds a predetermined maximum value. It mainly includes two types of short-circuit protection and overload protection. Short-circuit protection has the characteristics of large set current and instantaneous action. The characteristics of overload protection are mainly reflected in its small setting current and inverse time action.


Electromagnetic current trips (relays) and fuses in short-circuit protection are often used as short-circuit protection components. The time-delay electromagnetic current relay in overload protection is often used as an overload protection element.


Overcurrent protection can handle different types of faults in sections and conditions. In each stage, an over-current protection switch is set, and a part of the circuit is selectively cut off according to the current size, location, duration, etc. In fact, it is operated by three characteristics: inverse time characteristic, definite time characteristic, and quick-break characteristic.


Combining these three types, install them in different positions and set them reasonably, then the line protection can be divided by current, time, and section.


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