Tricky but Easy Electrical Engineering!
As we know that the secondary voltages of a 3-phase transformer may undergo a phase shift of either +30° leading or -30° lagging or 0° i.e. no phase shift or 180° reversal with respective line or phase to neutral voltages. On the name plate of a three phase transformer, the vector group is written as … Read more
The main and basic difference between a Power transformer and a Distribution Transformer is that Power transformers are used in transmission network of higher voltages for step-up and step down application like 400 kV, 200 kV, 110 kV, 66 kV, 33kV and are generally rated above 200 MVA. Distribution transformers are used for lower voltage … Read more
The core type transformers have many advantages over shell type transformers as follows: The core is greater than shell but the circular coils that are used are easier to wind. Provide more mechanical strength especially when short circuit occurs. High space factor and reduced mean length of turns resulting in reduced copper losses. Longer mean … Read more
Please have a look at the below figures of Squirrel Cage Induction and Wound Rotor / Slip Ring Induction Motor. The figure itself depicts many difference between the two types of motors. Don’t worry, difference between Squirrel Cage and Slip Ring type Induction Motor is tabulated after the figure. Squirrel Cage Induction Motor: Slip … Read more
Slip rings are used in rotating electrical assemblies to make a continuous electrical connection between stationary and moving conductors. This enables the stationary power source to transmit electrical power to the rotating component. Basically, a slip ring is a band of electrically conductive material mounted on a shaft. Although insulated from the shaft itself, the … Read more
Output voltage of a Synchronous Generator cannot contain even harmonics. For understanding the reason, carefully observe the figure below. As shown in the figure, one full pitched coil a and a’ are placed. The fundamental component of field flux wave induce maximum emf in coil sides a and a’ as these are cutting the maximum … Read more
In this post we will discuss about how to eliminate or suppress the harmonics from the emf waveform of an Alternator. In an Alternator, the primary source of harmonics in the emf waveform is due to non sinusoidal field waveform. If the field waveform would have been sinusoidal then there have been no harmonics in … Read more
We have already discussed about losses in electrical machine in “Losses in Electrical Machine – Core Loss”. Under normal operating condition, the core loss in the Rotor of an Induction Motor is negligible. In this post we will discuss about this. Core loss consists of Hysteresis Loss and Eddy Current Loss. Hysteresis Loss … Read more
A Squirrel Cage Induction Motor (SCIM) only has a cage rotor winding, whereas a synchronous machine has both a cage (damper) and a wound DC field winding as shown in figure below. Synchronous Motor with Damper Winding: Squirrel Cage Induction Motor: In both cases, and when using only the … Read more
Not only Transformers, even Alternators are rated in VA, kVA or MVA etc. The rating of a Transformer depends on the winding or oil temperature reaching the specified limiting value which is decided by the type of insulation minus a safety margin, something like 170 – 20 =150 °C. Now the temperature rises because of … Read more