Indepth Electrical engineering

Power Saving with VFDs in Induction Motors – Myths vs Facts Variable Frequency Drives (VFDs) are widely used in industries for speed control of fans, centrifugal pumps, compressors, and other variable torque applications . They not only regulate speed but also help in energy saving , depending upon the load requirements. However, there are a lot of myths around VFDs —especially the assumption that they always save power. Let’s break it down with facts, laws of affinity, and practical scenarios. Power Saving with VFDs – How It Works For variable torque loads like fans and pumps, the laws of affinity apply: Flow ∝ Speed Torque ∝ (Speed)² Power (Horsepower) ∝ (Speed)³ 👉 This means that even a small reduction in speed leads to a significant reduction in power consumption . For example: Reducing speed by 20% can cut power consumption by nearly 50%. VFDs can deliver up to 33% energy savings depending on the load profile. But below this limit, reducing speed...

In starters such as Star- Delta Starters, DOL Starters, Soft Starters whenever there is need of  changing  the direction of motor than that will be done by changing I/P leads, output leads of supply. This will leads to lot of effort making. This will also leads to loose connections.  There are also phase change-over's available in market for changing direction of motor.  In VFD connected motors if motors direction is need not be changed then there is no need to changing input and output connections. Below will explain the same:- Most often question comes in mind that is how to change direction of motor in VFD’s?? In VFD’S we can’t change the direction of motor by changing phase sequence from I/P supply. As in VFD’S motor I/P get converted into DC supply thereafter AC O/P will be generated through inverter. As any phase sequence of AC supply will get converted into DC thereafter that will converted into AC supply so Phase sequence will always remains same...

Variable frequency drives are most widely used for starting and running of Induction motors. The basic function of VFD’s is to control speed of motor according to load requirement which will also lead to power saving along with speed control. Although VFD’S cost initial cost is very high in comparison to Star- Delta and Soft- Starters but due to power saving application of VFD will leads to cover it’s extra cost very easily. Now let’s discuss how VFD’S work; VFD’S consists of following parts:- 1.Full wave rectifier 2.Filter circuit 3.Control circuit  4. Inverter circuit.  Circuit diagram consists of all parts is shown below:- VFD Circuit Diagram VFD circuit working is as discussed below:- First of all AC 3-Phase supply given at VFD I/P that I/P will get converted into DC through full wave rectifier if VFD is given 430 Phase to phase voltage then DC voltage that we get after full wave rectifier will be around about 690V. That voltage...

Basic Concepts of 3-Phase Induction Motor – An Electrical Engineer’s Perspective Introduction In modern industries, more than 80% of electrical drives rely on  induction motors , especially the  3-phase induction motor . Known as the “workhorse of the industry,” this machine is widely used due to its  rugged design, low cost, self-starting capability, and minimal maintenance needs . To understand why it is so popular, let us explore its  fundamental concepts, construction, and working principle . What is a 3-Phase Induction Motor? A  3-phase induction motor  is an  AC machine  that converts  electrical power into mechanical power . It works on the principle of  electromagnetic induction  discovered by Michael Faraday. That’s why it is called an  induction motor —because the rotor current is induced (not directly supplied) by the stator’s rotating magnetic field. Construction of a 3-Phase Induction Motor The motor has two major ...

Transformer Applications & Facts Transformers are among the most important electrical machines, widely used in power systems and electronics. They serve multiple functions depending on the requirement: 🔹 Main Applications of Transformers Voltage Transformation (Step-Up & Step-Down) Step-Up Transformers : Used at the transmission end to increase voltage and reduce current. This minimizes I 2 R I^2R losses in long-distance power transfer. Step-Down Transformers : Used at the distribution end to bring down voltage to safer, usable levels for consumers. Impedance Matching Transformers can match the load impedance with the source impedance. This ensures maximum power transfer to the load (commonly used in electronic and audio systems). Circuit Isolation Transformers provide galvanic isolation between circuits. They allow AC to pass while blocking DC, thereby preventing faults from propagating between circuits. Use in Electronics Power su...

Losses in Induction Motors: Constant and Variable Losses Explained Like transformers, induction motors also suffer from losses , which reduce efficiency. While transformers have only iron (core) losses and copper losses , induction motors additionally have mechanical losses because of their rotating parts. Thus, induction motor losses are broadly classified into two categories: Constant (Fixed) Losses Variable Losses Let’s study them in detail. 1. Constant (Fixed) Losses These are independent of motor load and remain nearly constant whether the motor runs at no-load or full load. (a) Core (Iron) Losses Hysteresis Loss Caused by magnetization and demagnetization of the core during each AC cycle. Reduced by using high-grade silicon steel laminations . Depends on supply frequency and maximum flux density. Eddy Current Loss Induced circulating currents in the core cause unwanted heating. Reduced by laminating the stator core , which increases r...

We have often seen in our routine that 3rd pin of plug top has larger length and diameter then other pins there is technical reasons behind the see below we will clear the same. This is due to following reason:- Resistance = Resistivity X Length                           Area larger will the area of earthing contact lower will be the resistance. You can see from the image below that earth pin has larger area then other pins. There are following reasons which we will derive from the larger 3rd pin are:- 1. It will provide protection to both human being and appliance by ensuring that 1st earth get connected before any appliance get supply and during disconnection of appliance earth will remains connected until supply get disconnected. 2. Due to larger area of earthing pin resistance get lower which will divert all fault current to earth quickly before it get passed to other system and may cause a...