STUDY & VLOGS

10/08/2025

05/08/2025

Village vlogs

05/08/2025

In some generators, the coil sides does not exactly correspond to adjacent North (N) and South (S) poles of the rotor. If they do, they are called full-pitch coils.If the sides of the coils span an arc whose angle is less than the angle spanned by adjacent N & S poles, these coils are called fractional-pitch coil.The physical or mechanical angle spanned by adjacent N & S poles known as the pole pitch (ρp) is dependent on the number of poles (P) of the rotor but are always 180 electrical degrees apart.

01/08/2025

Coal-fired power station layoutA typical coal-fired power station functions through a continuous, integrated process, broadly categorized into four main circuits: Coal and Ash Circuit: Coal is delivered, stored, prepared (sized), and fed to the boiler. Ash produced during combustion is collected and stored/disposed.Air and Gas Circuit: Air is drawn from the atmosphere by fans, preheated by flue gases, and used for combustion in the boiler. The hot flue gases pass through various components (superheater, economizer, air preheater, dust collector), before being exhausted via the chimney.Feedwater and Steam Flow Circuit: Water is treated, pumped to the boiler, converted to high-pressure steam by burning coal, superheated, and then expanded through a turbine to drive a generator, producing electricity. The spent steam is condensed and recirculated as feedwater.Cooling Water Circuit: Cooling water, drawn from a source (river, lake) or cooling towers, condenses the steam from the turbine. The heated water is either returned to the source or cooled in cooling towers and recirculated. These four interconnected circuits work in sequence to convert the chemical energy of coal into electrical energy.

31/07/2025

In electrical engineering, the pitch factor (Kp), also known as coil span factor, is a measure of how much the EMF (electromotive force) generated in a short-pitch coil differs from the EMF generated in a full-pitch coil. It's a ratio that quantifies the effect of shortening the coil span (the distance between the coil sides) on the induced voltage.
Key points about pitch factor:
Full-pitch coil:
A coil where the coil span is equal to the pole pitch (180 electrical degrees).
Short-pitch coil:
A coil where the coil span is less than the pole pitch.
Formula:
Kp = cos(α/2), where α is the short-pitch angle (the angle by which the coil is short-pitched).
Always less than 1:
Because a short-pitch coil will always have a lower induced EMF than a full-pitch coil, the pitch factor will always be less than 1.
Purpose of short-pitching:
Short-pitching is used to reduce the harmonics in the generated EMF, improving the waveform quality of the output voltage.
In simpler terms: Imagine two coils in a generator. One coil spans the full distance between poles, and the other spans a shorter distance. The pitch factor tells you how much smaller the voltage is in the shorter coil compared to the longer coil.

29/07/2025

The term "CR characteristics" generally refers to Critical Characteristics within a product or system, while "SCR characteristics" specifically relates to the behavior of a Silicon-Controlled Rectifier (SCR). Critical characteristics are features that, if faulty, could lead to failure or malfunction. SCRs are power semiconductor devices used for controlling current in circuits, and their behavior is defined by their voltage-current (V-I) characteristics and gate characteristics.
CR Characteristics (Critical Characteristics):
Definition:
Critical characteristics are features of a product, component, or system that, if not within specified limits, could cause a failure or malfunction.
Examples:
These could be dimensions, tolerances, material properties, assembly procedures, or inspection processes.
Importance:
Identifying and controlling critical characteristics ensures the product or system meets its intended function and avoids potential issues.
SCR Characteristics (Silicon-Controlled Rectifier):
Definition:
SCRs are four-layer (PNPN) semiconductor devices that act as controlled switches in power electronic circuits.
Structure:
They have three terminals: anode, cathode, and gate.
Working Principle:
SCRs can be turned ON by applying a voltage or current to the gate terminal and will remain ON until the current drops below a certain level (holding current).
Forward Blocking State:
When the anode is positive with respect to the cathode and the gate current is zero, the SCR acts as an open switch (small leakage current).
Reverse Blocking State:
When the anode is negative with respect to the cathode, the SCR acts as an open switch (small leakage current).
Forward Conduction State:
Once triggered by the gate, the SCR conducts current from anode to cathode.
SCR Characteristics:
V-I Characteristics: The relationship between anode-cathode voltage (V) and anode current (I).
Gate Characteristics: The safe limits for gate voltage and current required to trigger the SCR.
Latching Current: The minimum anode current required to maintain the SCR in the ON state after the gate signal is removed.
Holding Current: The minimum anode current required to keep the SCR conducting.
Breakover Voltage: The voltage at which the SCR switches from the forward blocking state to the forward conduction state without gate triggering.
Turn-on Time: The time it takes for the SCR to switch from the blocking to the conduction state after triggering.
Turn-off Time: The time it takes for the SCR to switch from the conduction to the blocking state.
Current Ratings: Maximum forward current, RMS current, etc.
Applications:
SCRs are used in a wide range of power control applications, including motor speed control, power supplies, lighting control, and inverters.

28/07/2025

28/07/2025

Kharagpur Balaji temple

28/07/2025

Kharagpur Balaji temple

28/07/2025

Balaji mondir

30/07/2024

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