What is Overcurrent Relay?DefinitionAn overcurrent relay is defined as a relay that activates only when the current value exceeds the relay's set value. It safeguards the equipment in the power system from fault currents.Classification Based on Operation TimeBased on the time it takes to operate, the overcurrent relay can be categorized into the following types: Instantaneous Overcurrent Relay Inverse Time Overcurrent Relay Definite Time Overcurrent Relay Inverse Definite Time Overcurrent Relay

In most types of Gas - Insulated Switchgear (GIS), the Ultra - High - Frequency (UHF) energy is concentrated within the frequency range of 100 MHz to 2 GHz. The frequency response of the sensor is contingent upon its size, shape, and the connection method employed. Most sensors are, in themselves, resonant structures at UHF frequencies, and this characteristic can be exploited to enhance performance. Typical sensors are depicted in the figure.Internal sensors are typically installed in a recess

What is Static Relay ？Definition: A relay that has no moving parts is referred to as a static relay. In this type of relay, the output is generated by static components such as magnetic and electronic circuits. Even if a relay combines static elements with an electromagnetic relay, it is still called a static relay. This is because the static units are responsible for sensing the input and generating a response, while the electromagnetic relay is merely utilized for the switching operation.The c

The partitioning of a Gas - Insulated Switchgear (GIS) is significantly influenced by the service continuity requirements during maintenance, repair, and extension activities. Additionally, local health and safety regulations must be taken into account.GIS should be divided into compartments in a way that:During various operations that necessitate the de - energization of certain parts of the GIS, such as maintenance, repair, and extension, the compartments taken out of service adhere to the use

Rogowski coils offer highly accurate secondary outputs without the risk of saturation since they do not incorporate an iron core. The air - core design ensures linear measurement, although it generates only a relatively small voltage (1V as opposed to 100V). This characteristic enables a compact equipment layout and allows for easy integration into Gas - Insulated Switchgear (GIS) with minimal space requirements due to the absence of an iron core. Additionally, Rogowski coils exhibit high immuni

Oil Circuit BreakerAn oil circuit breaker is a type of circuit breaker that utilizes oil as a dielectric or insulating medium for arc extinction. In an oil circuit breaker, the breaker's contacts are designed to separate within an insulating oil. When a fault occurs in the electrical system, the contacts of the circuit breaker open beneath the insulating oil, and an arc is generated between them. The heat of this arc causes the surrounding oil to vaporize. Oil circuit breakers are classified int

High - Speed Earth Switches (HSES) have two rated operating sequences:C–ti1–OC–ti1–O–ti2–C–ti1–Owhere:ti1 represents a time period that is longer than the time needed for secondary arc extinction and for the dielectric recovery of air insulation at the fault location. ti1 is determined by users while taking system stability into account. The recommended value of ti1 is 0.15 s.ti2 is the intermediate time specified by the system protection. ti2 enco

General Rules for GIS Grounding and bondingIn most Gas - Insulated Switchgears (GIS), there are two grounding grids:The station grounding grid, which is analogous to that in a typical Air - Insulated Switchgear (AIS) installation.The GIS grounding mesh, a closely - spaced grounding grid embedded in the concrete slab where the GIS is installed.Typical rules for GIS grounding and bonding are as follows:All grounding conductors should be kept as short as feasible.The grounding mesh and its intercon

Very Fast Transient Over voltage(VFTO) wave common characteristics in HV& EHV GISSteep wavefront, with a rise time typically ranging from 2 to 20 nanoseconds: When restriking occurs in the contact clearance of a disconnector, the arc - reignition process is extremely rapid. As a result, the voltage waveform injected into the power grid exhibits a very high ascending or descending steepness.Theoretically, the amplitude of Very Fast Transient Overvoltage (VFTO) can reach up to 3.0 per - unit.

Ground switches feature a moving contact that creates or closes a gap between the high - voltage conductor and the enclosure. At the enclosure and the conductor, sliding contacts equipped with suitable electric - field shields are incorporated.A “maintenance” ground switch can be operated either manually or via a motor drive. It takes several seconds to open or close, and when fully closed, it can carry the rated short - circuit current for the specified time period (either 1 or 3 seconds) witho