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

Fault PhenomenonOn June 23, 2020, a fault occurred in the 35 kV feeder bay that was on hot standby at a 220 kV substation. This triggered the operation of the first - stage, first - time - limit voltage - restrained overcurrent protection of the low - voltage backup protection of the No. 2 main transformer and the second - stage overcurrent protection of the 350 bus tie protection. Consequently, the 352 circuit breaker on the low - voltage side corresponding to the No. 2 main transformer and the

Outdoor vacuum circuit breakers (referred to as breakers hereinafter) are widely used in the distribution network due to their advantages such as small size, light weight, fire - and explosion - proof nature, smooth operation, low noise, small open - contact clearance, short arcing time, and easy maintenance. As atmospheric pollution becomes increasingly severe, in adverse weather conditions like heavy fog, drizzle, condensation, or ice melting, partial discharge (PD) is likely to occur on the s

Outdoor vacuum circuit breakers are predominantly utilized in the Medium High Voltage (MHV) segment. They serve as a crucial component in the distribution sector, especially within 11kV and 33kV grids. A variety of composite materials are employed in the construction of these breakers. Among them, the vacuum interrupter stands out as the most vital component. For outdoor circuit breakers, the vacuum interrupter is typically encased in a porcelain housing.These breakers are connected to the opera

IntelligenceIntelligent Monitoring and Diagnosis Multi - parameter Real - time Monitoring: Outdoor vacuum circuit breakers will be extensively integrated with various high - precision sensors, which are like the "sensory nerves" of the circuit breaker. For example, displacement sensors are used to accurately measure the contact travel, keeping track of the position changes of the contacts during the opening and closing processes in real - time; speed sensors are utilized to monitor the opening a

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

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

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 theelectrical 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 into

Lightning impulse voltage (LIWL) tests and switching impulse voltage tests are carried out to assess the dielectric stress resulting from transient over - voltages induced by lightning strikes and switching operations respectively. An impulse voltage generator produces a steep - front voltage waveform, which is then applied to the test object. A measurement system, consisting of a voltage divider and a digital recorder, is used to measure and analyze the test voltages and their waveforms.The fig

This test just apply to 3 pole operation circuit breakers.As Fig these circuits use a three-phase current source and, generally, two voltage sources. one voltage source provides the TRV for the first pole-to-clear and the other gives the recovery voltage for the second- and third poles-to-clear, in the case where these poles clear simultaneously as in non-effectively earthed systems.This system have following components: A three phase current source (G) Voltage source 1 with current injection pa

This test serves to ascertain the length and condition of the current - carrying section of the arcing contacts within SF6 circuit breakers. DRM (Dynamic Resistance Measurement) tests are carried out by passing DC current through the breaker's main contacts during the breaker's operation. Subsequently, the breaker analyser computes and plots the resistance as a function of time. When contact movement is concurrently recorded, the resistance at each contact position can be determined. Through DRM