Indepth Electrical engineering

Locked Rotor Current and Torque in Induction Motors What is Locked Rotor Current? Locked rotor current (LRC) is the maximum current drawn by an induction motor when its rotor is not rotating (locked condition) . At startup, since the motor speed is zero, the slip is 1 (100%), and the motor draws its highest current. This current is usually 3–8 times the full load current (FLC) . As the motor accelerates, the current gradually reduces until it stabilizes at the rated full load current. LRC depends on the motor design, type, and supply voltage (higher supply voltage → lower current for the same power). 👉 In other words, "locked rotor current" is the current drawn if the motor is energized but prevented from turning. Equivalent Circuit at Locked Rotor Condition At locked rotor, each stator phase behaves like a series R–L circuit . Resistance (R): Copper loss component. Inductance (L): Reactance due to leakage ...

For transmission of power at High voltage Transmission lines needed to be laid. For laying Transmission lines Transmission towers are most widely used in world. Transmission towers are used for following purposes:- 1.        To separate high voltage conductors from surroundings and from each other. 2.        To keep conductors at sufficient height for safe limits. An overhead transmission line usually consists of three conductors or bundles of conductors containing the three phases of the power system. The conductors are usually aluminum cable steel reinforced (ACSR), which are steel core (for strength) and aluminum wires (having low resistance) wrapped around the core. Tower designing is most important part as towers has to sustain natural calamities.  There are following parts in Transmission towers:- 1.        Tower top 2.        Cross a...

Cable Selection Guide: Voltage, Current Capacity, Insulation, and Installation Methods  Learn how to select the right electrical cables based on voltage level, current carrying capacity, insulation type, installation method, number of cores, and environmental conditions. Introduction Selecting the right power cable is crucial in electrical systems to ensure safety, efficiency, and long-term reliability. Cable selection depends on various factors such as voltage level, current carrying capacity (ampacity), insulation type, number of cores, installation method, and environmental conditions . Using the wrong cable can lead to overheating, excessive voltage drop, or even failure of the electrical system. 1. Cable Selection According to Voltage Level Cables are categorized based on their nominal voltage ratings. The classification is as follows: Low Tension (LT) Cables : Up to 1000 V High Tension (HT) Cables : Up to 11 kV Super Tension Cables : From 22 kV to 33 kV Ex...

High Tension (HT) Cables: Types, Components, and Insulation Levels High Tension (HT) cables are the backbone of modern electrical power systems. Electricity is transmitted and distributed over long distances using HT cables or conductors , making them an indispensable part of power networks. The most commonly used HT cables are XLPE (Cross-Linked Polyethylene) cables , which offer high insulation strength, thermal stability, and longer service life compared to traditional PVC cables. 🔹 Types of HT Cables HT cables are classified mainly into two types: Single Conductor HT Cable Contains a single conductor per cable. For a three-phase system, three separate cables are required. Three Conductor HT Cable Contains three conductors within a common jacket. Compact design, often used where space is limited. 🔹 Components of HT Cables Although HT cables may look different externally, they all share five essential parts : Conductor (Copper or Aluminum) ...

Cable Glands: Types, Applications, and Industrial Standards Cable glands are an essential component in electrical and instrumentation installations. They provide mechanical support, environmental protection, and safety for cables entering panels or enclosures. Functions of Cable Glands Cable glands are used for the following purposes: 1.       Strain relief – Prevents tension and stress at cable termination points. 2.       Earthing and grounding – In case of armored cables, they ensure effective bonding. 3.       Cable entry – Provides safe and sealed entry into electrical panels, junction boxes, and enclosures. Types of Cable Glands Different types of glands are used based on cable type and application: 1.       Indoor Glands (Brass material) – For general indoor use. 2.       Outdoor Glands (Brass material) – With wea...

Earth Leakage Circuit Breaker or ELCB As clear from the name these circuit breakers are used for protection against electrical shock in case of leakage currents. ELCB get tripped whenever there are leakage currents in circuit. There are two types of ELCB’s:-           Voltage ELCB 2.      Current ELCB Now let’s discuss the same:- 1.    Earth leakage circuit breaker Voltage Type:- As clear from the name these are voltage operated ELCB’s. These ELCB’s consists of relay coil . This relay coil is connected to the metallic body of equipment which is to be protected from earth leakage at one end and at other end it is connected to ground wire. If any fault occurs such as live wire touches the body than there will be voltage difference occur across the terminal of coil and earth. This voltage difference causes current to flow thus will operate relay and trips the ELCB. Voltage ELCB’s are available in various ranges thes...