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Surya 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
What are the short circuit withstand levels for 400kV, 220kV, and 132kV transformers? Ans: 400 kV transformers must withstand 63 kA for 1 second. 220 kV transformers must withstand 50 kA for 1 second and 40 kA for 3 seconds. 132 kV transformers must withstand 40 kA for 1 second and 31.5 kA for 3 … Read more
Type Tests for above 33KV up to 220KV XLPE Copper Cable Tests on Conductor Tests on Insulation 3. Measurement of Thickness of Insulation4. Measurement of tensile strength and elongation at break5. Thermal ageing in air oven6. Hot set test7. Shrinkage test8. Void and contaminants test Tests on semiconductive layers of the insulation 9. Resistivity test … Read more
A Milliken conductor is a specialized type of stranded electrical conductor. We primarily use this type of conductor in high-voltage (HV) and extra-high-voltage (EHV) power cables. Its design reduces the skin effect and, the proximity effect. Therefore, it improves current distribution in large cross-sectional conductors, typically those exceeding 800 mm² (e.g., 1000, 1200, 1600, 2000, … Read more
Before discussing the types of sheath bonding used in high voltage cable let us recall our knowledge regarding sheath and cause of induced voltage and current in the sheath of a HV cable. Actually, all types of bonding are used to limit the unwanted, induced voltage and current in a cable sheath. What is a … Read more
Sheath Voltage Limiters (SVL) As I have already told, in high-voltage cables, the metallic sheath plays an important role in protecting the conductor from external physical, environmental and electromagnetic influences. But due to electromagnetic induction of the current flowing through the main conductor, a voltage is developed along the sheath, especially in long cable runs. … Read more