Indepth Electrical engineering

🔋 Battery Rating Calculation for UPS Systems 1. Why Series Connection? Series Connection → Voltage adds up, current remains same. Example: 18 batteries × 12V each → 216V DC bus. 2. Formula for Battery Capacity (AH) Battery Capacity (AH) = D C   C u r r e n t × D u r a t i o n   ( H r s ) %   C a p a c i t y   U t i l i z a t i o n \text{Battery Capacity (AH)} = \frac{DC\ Current \times Duration\ (Hrs)}{\%\ Capacity\ Utilization} Where: D C   C u r r e n t = U P S   ( K V A ) × 1000 × L o a d   P F η i n v e r t e r × E n d   V o l t a g e DC\ Current = \frac{UPS\ (KVA) \times 1000 \times Load\ PF}{\eta_{inverter} \times End\ Voltage} V A H = A H × V n o m i n a l VAH = AH \times V_{nominal} 3. Worked Example (UPS = 5 KVA, 1 Hr Backup, 18 Batteries) Step 1 – Find DC Current: D C   C u r r e n t = 5 × 1000 × 1 0.95 × ( 10.5 × 18 ) = 27.85   A DC\ Current = \frac{5 \times 1000 \times 1}{0.95 \times (10...

Maximum Allowable Temperatures of Various Types of Insulation in Motors Insulation materials play a crucial role in determining the efficiency, safety, and lifespan of electrical machines such as motors and transformers. The permissible operating temperature of an insulation system is defined by its Insulation Class , and exceeding this limit drastically reduces the machine’s service life. Insulation Classes and Maximum Temperatures Insulation Class Maximum Permissible Temperature (°C) Typical Materials Used Y 90 Cotton, silk, paper A 105 Cotton, silk, paper impregnated with varnish, oil, or enamel E 120 Modified synthetic materials B 130 Mica, asbestos, glass fiber with varnish or adhesives F 155 Improved Class B with epoxy resins, mica, silicone varnish H 18...

🔑 Circuit Breaker Life (Mechanical vs Electrical Operations) 1. Mechanical Life (No-load ON/OFF cycles): ·          Refers to how many times a breaker can be operated (ON/OFF) without current load. ·          Purely mechanical endurance, limited by moving parts, springs, and latching systems. 2. Electrical Life (Load/Short-circuit switching operations): ·          Refers to the number of ON/OFF or trip operations under load/current. ·          Limited by arc-quenching capability and contact wear . 📊 MCCB (Moulded Case Circuit Breaker) Life Expectancy MCCB Rated Current Mechanical Life (Ops) Electrical Life (Ops) ≤ 100 A 8,500 1,500 100 A – 315 A 7,000 1,000 315 A – 630 A ...

Electrical Contactors Utilization Categories: AC1, AC2, AC3, AC4, and More Electrical contactors are one of the most important components in electrical power and control circuits. They are widely used for switching, controlling, and protecting loads such as motors, heaters, lighting, and capacitor banks. To ensure reliability and safety, contactors are classified into utilization categories based on their current making and breaking capacity. These categories are defined in IEC 60947-4-1 and depend on: Type of load (resistive, inductive, capacitive, motor, lighting) Operating duty (normal switching, frequent switching, inching, plugging, etc.) Current & voltage rating (AC or DC supply conditions) Understanding these utilization categories is essential for electrical engineers, designers, and maintenance teams while selecting the right contactor for an application. Common AC Utilization Ca...

There are two types of currents which every electrical engineer must know before selecting a Circuit breaker. These type of current are known as :- 1. Breaking current or Breaking capacity. 2. Making Current or Making Capacity. You may visit also at link below for MCB Characteristics:- http://electrialstandards.blogspot.in/2014/04/mcb-characteristics-and-applications-of.html Breaking capacity  :- Breaking capacity of a circuit breaker or fuse is defined as the interrupting capacity of Circuit breaker or fuse that they can interrupt without destroying that equipment . The   short circuit current   which can occur under   short circuit   conditions should not exceed the rated breaking capacity of the apparatus. If breaking. Otherwise breaking of the current cannot be guaranteed. Thus Breaking capacity of the circuit breaker refers to the maximum current in rms value the circuit breaker can interrupt. Breaking capacity is also in the orde...