Indepth Electrical engineering

Phase Sequence Change in 3-Phase Motors In electrical systems, there are certain applications where the phase sequence of a 3-phase motor needs to be changed. This usually happens in plants that rely on external power distribution companies instead of their own captive power supply, as utility-supplied phase sequence may vary at times. The phase sequence determines the direction of rotation of a 3-phase induction motor. By interchanging any two supply phases, the motor’s direction can be reversed. 1. Phase Sequence Change in Star-Delta Starter In a Star-Delta Starter , six motor leads are connected to the starter. Phase sequence can be changed by interchanging two phases in each group of three-phase connections . This ensures that the motor rotates in the desired direction when switching between star and delta modes. 2. Phase Sequence Change in DOL / Soft Starters For Direct-On-Line (DOL) Starters and Soft Starters , phase sequence can be easily changed at the...

📊 Electrical Parameters for Motor Installation & Testing For every motor installation, an electrical engineer must calculate certain parameters to ensure correct sizing, protection, and performance monitoring. The following formulas apply to Alternating Current (AC) motors in both single-phase and three-phase systems. 1. Current (Amperes) when Horsepower (HP) is known Single-phase: I = H P × 746 E × η × p f I = \frac{HP \times 746}{E \times \eta \times pf} Three-phase: I = H P × 746 1.73 × E × η × p f I = \frac{HP \times 746}{1.73 \times E \times \eta \times pf} 2. Current (Amperes) when Kilowatts (kW) are known Single-phase: I = k W × 1000 E × p f I = \frac{kW \times 1000}{E \times pf} Three-phase: I = k W × 1000 1.73 × E × p f I = \frac{kW \times 1000}{1.73 \times E \times pf} 3. Current (Amperes) when kVA is known Single-phase: I = k V A × 1000 E I = \frac{kVA \times 1000}{E} Three-phase: I = k V A × 1000 1.73 × E I = \frac{kVA \ti...

📘 Essential Induction Motor Formulas (Quick Reference for Electrical Engineers) 1. High Inertia Loads (Acceleration Time & Torque) Acceleration Time (t): t = W K 2 × rpm 308 × T a v t = \frac{WK^2 \times \text{rpm}}{308 \times T_{av}} Required Torque (Tav): T a v = W K 2 × rpm 308 × t T_{av} = \frac{WK^2 \times \text{rpm}}{308 \times t} W K 2 WK^2 = Inertia in lb·ft² t t = Accelerating time in seconds T a v T_{av} = Average accelerating torque in lb·ft 👉 Usage: Use first formula if you know torque and want to find acceleration time. Use second formula if you know acceleration time and want required torque. Inertia Reflected to Motor J m o t o r = J l o a d × ( N l o a d N m o t o r ) 2 J_{motor} = J_{load} \times \left(\frac{N_{load}}{N_{motor}}\right)^2 2. Synchronous Speed, Frequency, and Poles Synchronous Speed: n s = 120 × f P n_s = \frac{120 \times f}{P} Frequency: f = P × n s 120 f = \frac{P \times n_s}{120} Number of Poles: P = 120 ×...

Rules Of Thumb (Approximation) At 1800 rpm, a motor develops a 3 lb.ft. per hp At 1200 rpm, a motor develops a 4.5 lb.ft. per hp At 575 volts, a 3-phase motor draws 1 amp per hp At 460 volts, a 3-phase motor draws 1.25 amp per hp At 230 volts a 3-phase motor draws 2.5 amp per hp At 230 volts, a single-phase motor draws 5 amp per hp At 115 volts, a single-phase motor draws 10 amp per hp Mechanical Formulas Torque in lb.ft. = HP x 5250 rpm HP = Torque x rpm 5250 rpm = 120 x Frequency No. of Poles Temperature Conversion Deg C = (Deg F - 32) x 5/9 Deg F = (Deg C x 9/5) + 32 

Can ever imagine how dangerous are electrical faults??? Let me give you one fact about electrical faults and their levels. Temperature produced during electrical arc-flash can reach 35,000 _F (19,500 _C).  These extremely high temperatures will easily melt copper conductors. Copper expands by a factor of 67,000 times at such high temperatures Usually such faults occurred during Short circuit of copper bus bars. When Human comes directly short circuit with two phases. The dangers associated with these faults are:- 1. High pressures 2. High level of Sound 3. Very high currents These high pressures can easily exceed 100-1000  pounds per square foot. Such faults produce high sounds which seems like a bomb get blasted and even causes damages to ladders, Humans etc. The sounds associated with these pressures can exceed 160 dB. The electrical current levels associated with electrical shock are measured in milli-amperes or one-thousandth of ...

Both Cables are widely used in Industries: PVC - stands for polyvinyl chloride  XLPE - is cross linked polyethylene cable.  Main Thumb rule for differentiation is that XLPE cables can be used for both HT and LT lines. But PVC Cables can be used only for LT lines. XLPE can withstand a higher temperature than PVC without detriment. This means that more current can be conducted for the same cross sectional area of copper. This means a big saving in cables costs.  Visit link below for more details:- http://electrialstandards.blogspot.com/2014/04/66kv-to-132kv-tests-requirement.html http://electricalsystembasics.com/2014/04/xlpe-cables-advantages-oil-filled-paper-insulated-cables.html XLPE Cables useful properties are :- XLPE Cables construction:- 1.Temperature  resistance 2. Stress rupture resistance  3. Environmental stress crack resistance  4. Resistance to U .V light 5. Chemical resistance 6. Oxidation resistance ...

📘 Cable Nomenclature Explained (PVC & XLPE Cables) Cable designations like YWY, AYFY, A2XCY might look confusing at first glance. But once you understand the logic behind each letter , reading technical specs becomes straightforward. 1. Basic Conductor Material ·          A → Aluminium conductor ·          (If “A” is absent, it means Copper conductor) 2. Insulation Material ·          Y → TROPODUR = PVC insulation ·          2X → TROPOTHEN-X = XLPE insulation 3. Armouring Types ·          W → Round Steel Wire Armouring ·          WW → Double Round Steel Wire Armouring ·          F → Flat (formed) Steel Strip Armouring ·       ...

📘 Categorized IEC Standards Reference 🔌 Cables & Conductors IEC 60228 – Conductors of insulated cables IEC 60245 – Rubber-insulated cables IEC 60183 – Guide to selection of high-voltage cables IEC 60287 – Calculation of permissible current in cables (steady-state rating) IEC 60092-350 – Shipboard power cables (construction & test requirements) ⚡ Switchgear, Bushings & Transformers IEC 60137 – Bushings for alternating voltages above 1 kV IEC 60214 – On-load tap changers IEC 60296 – Mineral insulating oils for transformers & switchgear IEC 60298 – High-voltage switchgear in metallic enclosure 🔋 Semiconductors & Power Electronics IEC 60134 – Absolute maximum & design ratings of tubes and semiconductor devices IEC 60146 – Semiconductor converters 📡 Connectors & Insulators IEC 60169 – Radio-frequency connectors IEC 60233 – Tests on hollow insulators for use in electrical equipment 🔧 Relay...

🔹 Categorized IEC 60027- IEC 60099 Standards General & Vocabulary IEC 60027 – Letter symbols in electrical technology IEC 60038 – Standard voltages IEC 60050 – International Electrotechnical Vocabulary IEC 60063 – Preferred number series (resistors, capacitors) Components & Devices IEC 60062 – Marking codes for resistors & capacitors IEC 60065 – Audio, video & electronic apparatus safety IEC 60085 – Electrical insulation IEC 60086 – Primary batteries IEC 60094 – Magnetic tape sound recording systems IEC 60096 – RF cables IEC 60098 – Rumble measurement on vinyl disc turntables Machines & Transformers IEC 60034 – Rotating electrical machinery IEC 60044 – Instrument transformers IEC 60076 – Power transformers System Protection & Coordination IEC 60068 – Environmental testing IEC 60071 – Insulation coordination IEC 60073 – Basic safety principles (man-machine interface, marking, identif...