Free Expert Guides on Power Systems, Circuit Design & Electrical Troubleshooting

Hey everyone, I'm Oliver, and I've been working with current transformers (CTs) and voltage transformers (VTs) for 8 years.From assisting my mentor on site to leading high-voltage testing teams and conducting error calibrations independently, I’ve dealt with all kinds of instrument transformers — especially those used in GIS systems. The error test for voltage transformers is something I perform regularly.A few days ago, a friend asked me: “Oliver, how exactly do yo

1. Accident OverviewA newly - built 110kV substation’s GIS exploded during commissioning due to a PT secondary circuit short - circuit. Though the cause was simple, consequences were severe, warranting reflection.2. Accident ProcessOn the power - transmission day: The upper - level power supply charged the 110kV GIS (a combined appliance). 20s after closing the incoming switch and first live - impacting the 110kV bus, white smoke emerged between the PT compartment and control cabinet.

1. Causes of ResonanceA 500kV GIS switching station is designed following the principle of “primary equipment intelligence and secondary equipment networking”. The PT high - voltage side has no disconnector and is directly connected to the bus GIS. Through the analysis of fault recording diagrams, when the 5021 circuit breaker opens, the fracture capacitance and PT form a series circuit. Moreover, the bus voltage, after being paralleled by the PT inductance, shows inductive c

Hi everyone, I'm James, and I've been working with current transformers (CTs) for 10 years. Today, I’ll talk about what you need to watch out for when selecting and installing GIS current transformers.Part 1: Key Considerations During Selection1. Accuracy Class Protection-grade CTs: Used for relay protection — focus on overload capacity and transient response. Metering-grade CTs: Used for billing purposes — require high accuracy, usually 0.2S or 0.5S class.2. Rated

In UHV GIS, current transformers are key to electric energy metering. Their accuracy determines power trade settlements, so on - site error verification perJJG1021 - 2007is needed. On - site, use power supplies, voltage regulators, and current boosters. Due to encapsulation in GIS, build test circuits via exposed grounding knives, bushings, and return conductors; right circuits simplify wiring and boost accuracy.Challenges like large test current, long circuits, and high impedance exist, but rea

I’m Oliver, an 8 - year current transformer testing pro. Today, let’s break down new and old polarity test methods for GIS current transformers—how they work and their pros/cons.1.Testing Methods1.1New Method Pre - test ops: Open FDS21/FDS22 fast disconnectors + DS23 disconnector. Close CB21 breaker, then ES21/ES22 grounding disconnectors. Disconnect ES21’s SF6 - shell ground. Wiring: Connect battery between ES21’s moving contact (negative ground

1.Design and Application Example of Photoelectric Current Transformer in GISThis article takes a 126kV GIS project as a specific example to deeply explore the design ideas and practical application of photoelectric current transformers in the GIS system. Since this GIS project was officially put into operation, the power system has remained stable, with no major failures occurring, and the operation status is relatively ideal.1.1 Design and Application Ideas of Photoelectric Current TransformerI

I'm Oliver, with 8 years of experience in current transformer testing. These are all practical experiences, shared with you1 Maintenance of Current TransformersHaving been in the business of current transformer testing for 8 years, I know a thing or two about their maintenance! The maintenance of current transformers is divided into minor repairs, intermediate repairs, and major overhauls.Minor repairs mainly involve opening the cover (if necessary) and changing the oil, usually carried out once

Gas - insulated switchgear (GIS) , often called “SF6 combined electrical apparatus”, is widely used in power systems for its high reliability, small footprint, low noise, and low loss. It encloses high - voltage devices like circuit breakers, fast grounding switches, current transformers, and busbars in a grounded metal shell filled withSF6gas. Each device sits in a separate gas chamber with different pressures. The CT terminal block divides gas chambers, connects components,

Modularization of High - Voltage SwitchgearDue to the miniaturization measures taken for each component and part, as well as the overall miniaturized layout, the size of high - voltage switchgear has been continuously decreasing. There is a wide variety of switchgear combinations, with flexible combination methods and very compact structures. Gas - insulated metal - enclosed switchgear (GIS) encompasses most high - voltage electrical appliances and protective detecting devices, integrating the f