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

In power systems, voltage transformers in GIS (Gas Insulated Switchgear) play a crucial role in voltage measurement and relay protection. Selecting the right model and installing it correctly is vital for the stable operation of the equipment. The following points should be noted regarding selection and installation.I. Key Points for Selection(1) Matching Rated Parameters Voltage Level: It must be consistent with the voltage level of the GIS system. For example, 110kV and 220kV GIS systems requi

1. Accident Overview1.1 Structure and Connection of 35kV GIS Switchgear Voltage TransformerThe ZX2 gas-insulated double-bus switchgear, manufactured in March 2011 and officially put into operation in July 2012, is configured with two groups of bus voltage transformers (PTs) for each bus section. The two PT groups of the same bus section are designed in one switchgear cabinet with a width of 600 mm. The three-phase PTs are arranged in a triangular formation at the bottom of the cabinet.The PTs ar

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

Automatic backup switching (ABTS) devices are core components ensuring the safe, reliable, and stable operation of factory power grids. Their startup logic strictly follows the dual criteria of "loss of voltage in the working power supply + no - current detection", effectively avoiding misjudgments caused by secondary disconnection of voltage transformers (VTs) or maloperations of ABTS due to secondary circuit faults of current transformers (CTs). The activation condition requires both "no volta

By Echo, 12 Years in the Electrical IndustryHi everyone, I'm Echo, and I've been working in the electrical industry for 12 years.From early involvement in commissioning and maintenance of distribution rooms to later participation in electrical system design and equipment selection for large-scale projects, I’ve witnessed how voltage transformers have evolved — from traditional analog devices to intelligent, digital components.The other day, a new colleague from a power compan

With the rapid development of power systems, electronic voltage transformers (EVTs), as key measurement devices in power systems, their performance stability and reliability are crucial for the safe and stable operation of power systems. The electromagnetic compatibility (EMC) performance, as one of the core indicators of EVTs, is directly related to the ability of the device to work normally in complex electromagnetic environments and whether it will cause electromagnetic interference to other

What is Arc Interruption Theory?Arc Interruption Theory DefinitionArc interruption theory is defined as the process of stopping electrical arcs that occur when circuit contacts open.Methods of Arc InterruptionThere are two main methods: the high resistance method, which increases resistance to zero current, and the low resistance method, which uses the natural zero point of AC current.Restriking VoltageRestriking voltage is the voltage across breaker contacts at the moment an arc is extinguished

Doping DefinitionDoping is the process of adding impurities to a semiconductor to change its conductive properties.Donor ImpuritiesDonor impurities are pentavalent atoms added to semiconductors, contributing extra free electrons, creating n-type semiconductors.N-Type SemiconductorWhen n-type or donor impurities are added to a semiconductor, the forbidden energy gap in the lattice structure narrows. Donor atoms introduce new energy levels just below the conduction band. These levels are discrete