How to Select Low-Voltage Electrical Apparatus: Two Key Principles and Four Important ConsiderationsWhen selecting low-voltage electrical devices, two fundamental principles must be followed: safety and economy. Additionally, there are several critical factors to consider. Those unfamiliar with the process should refer to the guidelines below.I. Two Core Principles for Selecting Low-Voltage Electrical Apparatus Safety PrincipleThe selected low-voltage devices must operate accurately and reliably

In substations, the number of isolating switches is generally 2 to 4 times that of circuit breakers. Due to their large quantity, the workload for installation and commissioning is considerable. For voltage levels below 110 kV, the GW4-type isolating switch serves as the dominant equipment. If the installation workmanship and mechanical dimensional adjustments of the isolating switch do not meet requirements, issues such as incomplete opening/closing, overheated contacts, or even porcelain insul

When performing switching operations, operating personnel must carefully verify that the circuit breaker is indeed in the open position. For three-pole interlocked isolating switches, all three phases must move simultaneously, with a maximum allowable vertical discrepancy of no more than 3 mm, before any opening or closing operation of the isolating switch is permitted.1. Key Points for Closing an Isolating SwitchFor manual operation, operating personnel should first remove the interlock pin bef

Installation Requirements for Isolating SwitchesBefore installing an isolating switch, a thorough visual inspection must be carried out. The main items to check include:(1) Verify that the model and specifications of the isolating switch match the design requirements.(2) Inspect all components for damage and check whether the blade or contacts are deformed. If deformation is found, it should be corrected.(3) Examine the contact condition between the movable blade and the contacts. Any copper oxi

IEEE Std C37.20.9™ defines the design, testing, and installation requirements for metal-enclosed gas-insulated switchgear (MEGIS) using gas at pressures above ambient as the primary insulation medium for alternating current systems rated from 1 kV to 52 kV. This includes, but is not limited to, circuit breakers, switches, bushings, busbars, instrument transformers, cable terminations, meters, and control/protection relays. In these switchgear assemblies, vertical compartments—some or all of the

High-voltage disconnectors require operating mechanisms with fast response and high output torque. Most current motor-driven mechanisms rely on a series of reduction components, yet motor-operated mechanism control systems effectively meet these requirements.1. Overview of the Motor-Operated Mechanism Control System for High-Voltage Disconnectors1.1 Basic ConceptThe motor-operated mechanism control system primarily refers to a system that employs a dual-loop PID control strategy to regulate moto

1.Working Principle and Structural Features of GW4-126 DisconnectorThe GW4-126 disconnector is suitable for AC 50/60 Hz power lines with a rated voltage of 110 kV. It is used to disconnect or connect high-voltage circuits under no-load conditions, enabling circuit switching, operational mode changes, and safe electrical isolation of busbars, circuit breakers, and other high-voltage equipment during maintenance. Disconnectors typically feature a clearly visible open point to ensure safe current i

High-voltage vacuum circuit breakers are widely used across China’s power industry—in urban and rural power grid upgrades, chemical plants, metallurgy, railway electrification, mining, and other sectors—thanks to their excellent arc-quenching characteristics, suitability for frequent operations, and long maintenance-free intervals. They have received widespread acclaim from users.The primary advantage of vacuum circuit breakers lies in the vacuum interrupter; however, a long maintenance-free int

Selection Guidelines for 36 kV Disconnect SwitchesWhen selecting the rated voltage, ensure that the disconnect switch’s rated voltage is equal to or higher than the nominal voltage of the power system at the installation point. For example, in a typical 36 kV power network, the disconnect switch must have a rated voltage of at least 36 kV.For rated current, selection should be based on the actual long-term load current. Generally, the switch’s rated current must be no less than the maximum conti

First, the installation of 10 kV high-voltage disconnect switches must meet the following requirements. The first step is to select an appropriate installation location, typically near the switchgear power supply in the power system to facilitate operation and maintenance. At the same time, sufficient space must be ensured at the installation site to accommodate equipment placement and wiring.Secondly, equipment safety must be fully considered—for example, lightning protection and explosion-proo