As an indispensable component in the power system, protection relay silently guards the safe and stable operation of the whole system. The next article will introduce you to the definition of the protective relay, the principle of operation, classification and its important role in the power system, so that you understand this key electronic components.
The definition and basic principle of the protection relay.
Protection relay is a power system can automatically detect the operating state, when anomalies or faults, rapid action and signal or the implementation of the corresponding protection measures of automation appliances. Its working principle is based on real-time monitoring and analysis of various electrical quantities in the power system, such as current, voltage, power, frequency and so on.
When these electrical quantities deviate from the normal range to a certain extent, the protection relay will be based on the preset action value and logical relationship, start the protection device, such as cutting off the circuit, in order to prevent further expansion of the fault, to protect the power equipment and personnel safety.
The structure of the protective relay analyzes
1. Measuring element
Measuring element is the “sense organ” of the protection relay, responsible for collecting electrical quantities in the power system and converting them into signals suitable for subsequent processing. Examples include current transformers and voltage transformers, which respectively convert large currents and high voltages in the system proportionally into small currents and low voltages for accurate measurement and analysis by the measuring element.
2. Logic elements
3. Execution element
The execution element is the “executor” of the protection relay, when receiving the control signal from the logic element, the execution element will act quickly to realize the protection of the power system. Common execution elements are relay contacts, which control the tripping or closing of circuit breakers through the closure or disconnection of the contacts, thus cutting off the faulty circuit.
Classification and characteristics of protective relays
1. current protection relay
Current protection relay mainly according to the size of the current to determine whether there is a fault in the power system. When the system current exceeds the set value of the action current, the current protection relay will act, commonly used in short-circuit fault protection. It is characterized by simple principle and quick action, but is greatly affected by the system operation mode. Resistor color code
2. Voltage protection relay
3. Differential protection relay
Differential protection relay by comparing the current size and phase of the two ends of the protected equipment, when the difference between the two exceeds the allowable range of action. It is sensitive to the internal faults of the protected equipment, can quickly remove the fault, widely used in transformers, generators and other important equipment protection.
The importance of protective relays in the power system
In the power system, the protective relay plays a vital role. It can quickly and accurately detect faults, take timely protective measures to avoid the expansion of the scope of the fault, and reduce power outage time and economic losses. For example, when a short-circuit fault occurs in a high-voltage transmission line, the protective relay can make the circuit breaker trip in a very short time, cut off the fault line, and guarantee the stable operation of other normal lines.
Meanwhile, protective relay is also an important part of power system automation and intelligence, which provides a solid guarantee for the reliable operation of power system.
At MobikeChip, we offer a wealth of knowledge about electronic components and quality products. Understanding protective relays will help you better understand the operation and maintenance of power systems. If you have any questions about the selection and application of protective relays, please feel free to visit MobikeChip's website and our professional team will be happy to serve you.
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