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The Nitrogen Injection Fire Protection System (NIFPS) is designed to prevent and extinguish fires in oil-filled transformers, thereby safeguarding critical power infrastructure. This system operates on a “drain and stir” principle, effectively mitigating fire hazards through a coordinated sequence of actions. Working Principle of NIFPS As it is an protection system it first needs to … 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
A Milliken conductor is a specialized type of stranded electrical conductor used primarily in high-voltage (HV) and extra-high-voltage (EHV) power cables. It is designed to reduce the skin effect, proximity effect, and improve current distribution in large cross-sectional conductors, typically those exceeding 800 mm² (e.g., 1000, 1200, 1600, 2000, 2500, or even 3000 mm²). Structure … 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
Measuring soil resistivity is essential before designing a grounded earthing system for a substation because it determines how well the ground can dissipate fault currents. If the soil resistivity is high, the grounding system needs more dense earthing mesh and more number of conductive electrodes to ensure proper safety. A well-designed earthing system prevents intolerable … 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
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
Single Bus System with Bus Sectionalizer Because of cheapness and simplicity, single bus-bar is adopted with sectionalizing arrangements, as shown in the figure below. Full advantage of the scheme is realized if the incoming and outgoing circuits are distributed evenly on the sections. Where double feed is provided for any single load it is preferable … Read more
What type of circuit breaker is generally used for the 36KV class ?Ans: The 36KV class circuit breaker is normally an outdoor type Vacuum Circuit Breaker (VCB). Why is VCB Preferred in 33KV Outdoor Systems Over SF6 Circuit Breakers?Ans: VCBs are more economical for 33KV systems compared to SF6 circuit breakers due to simpler construction … Read more
A high voltage circuit breaker plays a crucial role in power systems by protecting electrical equipment from damage due to electrical faults in the system. One of the key challenges in circuit breaker design is dealing with the transient recovery voltage (TRV), a phenomenon that occurs immediately after current interruption. When a fault current gets … Read more