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 you perform an

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.Within

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 character

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 ClassProtection-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 Primary Curren

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 MethodPre - 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 grounded) + ground electrode