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We also refer to the Core Balance Current Transformer or Core Balance CT (CBCT) as Working Principle of Core Balance CT (CBCT) A Core Balance Current Transformer (CBCT) is a special type of current transformer. Specifically, it works on the principle of imbalance detection. It monitors the imbalance current of a three-phase cable system. When … Read more
Type Tests of Capacitive Voltage Transformer (CVT) These tests are done according to IS: 3156 (Part-1) Routine Tests These tests are done according to IS: 3156 (Part-1)
As the name suggests, ferroresonance is a resonance phenomenon related to iron. Ferro means ‘iron’. Before understanding the ferroresonance, let us recall the concept of resonance first. Suppose, we have a series RLC circuit, across which a voltage source is connected. Say a current I flowing through the circuit. VL is the voltage developed across … Read more
Conductor of an EHV Cable This is the main part of the cable. The one and only purpose of a cable is to carry electric current. The conductor performs that task. The conductor of an EHV XLPE cable is normally stranded. It is needless to say that the stranding is done to reduce the skin … Read more
Some the important parameters are listed here for the reference only. The actual technical parameters of a potential transformer may be somewhat different depending on the actual requirements.
An Oil Surge Relay, or OSR, is a type of mechanical relay. It operates in response to a sudden oil surge. Need for Separate Diverter Tank Every modern power transformer includes an On-Load Tap Changer (OLTC). During tap-changing operations, some arcing always occurs at the diverter switch contacts. It is desirable to change tap positions … Read more
XLPE stands for Cross Linked Polyethylene. This is a type of polymer insulation widely used in electrical power cables, especially in high voltage (HV) and extra-high voltage (EHV) applications. It is derived from polyethylene but has been chemically modified to improve its thermal, mechanical, and electrical properties. Key Features of XLPE Cross-Linking Process: In standard … Read more
The Nitrogen Injection Fire Protection System (NIFPS) prevents and extinguishes fires in oil-filled transformers. Thereby, it safeguards critical power infrastructure. We also commonly call it the Nitrogen Injection Fire Prevention & Extinguishing System (NIFPES). This system operates on a “drain and stir” principle, effectively mitigating fire hazards through a coordinated sequence of actions. Working Principle … Read more
Type Tests on a Lightning Arrester as per IS 3070 Routine Tests on a Lightning Arrester as per IS 3070 Routine Tests on a Surge Monitor Acceptance Tests on a Lightning Arrester Acceptance Test on a Surge Monitor
A power transformer has high cost, large size, and complex design. So, identifying defects at the final stage of manufacturing can lead to significant delays, expenses, and operational challenges. Therefore, standards always recommend performing different tests and inspections during various stages of manufacturing. That means the standards always prefer to perform stage inspections of a … Read more
Type Tests of Isolators as per IS 9921 (Part 4) – 1985 The type tests of isolators are conducted to ensure that the isolators meet the performance criteria under standard operating conditions. According to IS 9921 (Part 4) – 1985, the type tests of isolators can be broadly categorized into the following: These type tests … Read more
What is the Rated Voltage Factor in voltage transformers, and how is it determined? This is the ratio of the maximum operating voltage to the rated primary voltage of the PT. We have to multiply this factor by the primary rated voltage. This determines the maximum operating voltage of the PT. In other words, this … Read more
What is the definition of the rated voltage of a lightning arrester? As per IS 3070, the definition of the “rated voltage of a Lightning Arrester” is given below.The maximum permissible r.m.s. value of power-frequency voltage between the line and earth terminal under temporary over-voltage conditions for a duration of 10 seconds as established in … Read more
Type Tests on Capacitor Bank Routine Tests on Capacitor Bank Acceptance Tests on Capacitor Bank The type tests and routine tests are repeated on samples as factory acceptance tests.
The clearance requirements for HV and LV terminals in the air are as follows:For 66 kV side, the phase-to-phase and phase-to-earth clearance should be 700 mm, and 660 mm respectively.For 12 kV side, the phase-to-phase and phase-to-earth clearance should be 280 mm, and 140 mm respectively. The following points should be noted for designing winding … Read more
A Digital Teleprotection Coupler (DTPC) is often referred as a Digital Protection Coupler (DPC). It serves as a high-speed, reliable interface for transmitting protection commands between substations over a communication medium (OPGW). Typically it is used for carrier protection of transmission lines. Working Principle First, a protective relay such as a digital distance relay or … Read more
What is a partial discharge in an insulation system? A partial discharge (PD) in an insulator system is a localized electrical discharge that occurs when the electric field within the insulation exceeds its dielectric strength in specific areas, without completely bridging the insulating material between conductors. When high voltage is applied to an insulation system, … Read more
A miniature circuit breaker, or MCB, is an essential protective device in low-voltage electrical systems because it protects the circuit from both overload and short-circuit faults. Let us explore the constructional details and the working of an MCB. Introduction to MCB An MCB has two main functions. We can use it as a toggle switch … Read more
Power transformers are critical to electrical systems, and their failure can lead to major disruptions. Sweep Frequency Response Analysis (SFRA) is a powerful diagnostic tool used to detect mechanical and electrical issues inside a transformer before they cause serious problems. It helps identify winding movement, core displacement, insulation failure, and structural deformations by analyzing how … Read more