Technical Knowledge Sharing

33 kV Medium Voltage Switchgear: Common Types, Functional Configurations and Selection Guide

33 kV medium voltage switchgear is used to receive, distribute, control, protect and monitor electrical power in 33 kV distribution systems. Typical applications include industrial substations, utility distribution substations, power plants, and step-up substations for solar PV and wind farms. Common types and product ranges include KYN61-40.5, XGN□-40.5, PIX 36, F400/F400xe, 8DA10 and 8DB10. These […]

2026-11-08

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Distance Protection Relays (ANSI 21): Working Principle, Functions and Setting Calculations

Distance protection relays (ANSI 21) use fault-loop voltage and current phasors to calculate the apparent impedance seen from the relay location. They determine whether a fault lies within a protection zone by applying directional criteria, impedance operating characteristics and time coordination. For a uniform line under ideal conditions, such as a bolted fault, the measured […]

2026-11-08

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What Are the Advantages of Wall-Mounted DC Power Supply Systems?

The main advantage of a wall-mounted DC power supply system is its ability to integrate rectification and battery charging, battery-backed supply, DC distribution and intelligent monitoring within a compact installation. It provides a space-saving, manageable DC auxiliary power solution for applications with relatively low DC loads. Wall-mounted DC power supply systems are well suited to […]

2026-11-06

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Overvoltage Protection Relay (ANSI 59): Working Principle, Functions and Setting Calculations

An overvoltage protection relay is a digital protection device designed to detect abnormal voltage rises in electrical power systems and initiate alarms, circuit-breaker tripping or other control actions according to predefined voltage thresholds, operating delays and protection logic. The ANSI device function number for overvoltage protection is 59. This protection function is primarily used to […]

2026-11-03

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Substation Protection Relays : Types, Functions & Selection Guide

1. What Are Substation Protection Relays? Substation protection relays are essential components of electrical power system protection. They monitor the operating conditions of transmission lines, power transformers, busbars, capacitor banks and other electrical equipment within substations. When faults or abnormal conditions occur, such as short circuits, earth faults, overloads, abnormal voltages or frequency deviations, protection […]

2026-11-02

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Power Plant SCADA System: Architecture, Components, Functions and Applications

A Power Plant SCADA System (Supervisory Control and Data Acquisition System) is an essential part of modern power plant electrical automation. It provides real-time monitoring, data acquisition, supervisory control and operational management for generators, power transformers, switchgear, auxiliary electrical distribution systems and associated plant equipment. Modern power plant SCADA systems integrate equipment supervision, alarm management, […]

2026-10-29

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Undervoltage Protection (ANSI 27): Working Principle, Functions and Setting Calculations

1. What Is Undervoltage Protection (ANSI 27)? Undervoltage protection (ANSI 27) is a voltage-based protection function designed to detect when the measured system voltage falls below a configured threshold for a specified period. It is widely used in medium-voltage and low-voltage power distribution systems, industrial electrical installations, substations, motor control systems and power generation facilities. […]

2026-10-29

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Distributed DC Power Supply Systems: Working Principle, Advantages and Disadvantages, Applications and Selection Guide

1. What Is a Distributed DC Power Supply System? A distributed DC power supply system provides DC auxiliary power through individual supply units installed close to the equipment they serve. This localised approach can be particularly useful for medium-voltage switchgear, ring main units (RMUs), compact substations, distribution automation equipment and industrial power distribution systems. For […]

2026-10-29

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