ELECTRICAL EASY

Variable Frequency Transformer or simply VFT is quite a new technology to connect two asynchronous Grids. Asynchronous Grids mean two power systems operating at two different frequencies. The world’s first VFT was installed and commissioned in the year of 2004 at Hydro- Quebec’s Langlois substation, where it is used to exchange up to 100 MW of power between the asynchronous power grids of Quebec (Canada) and New York (USA).  First thing to note here that though the name suggests it to be Transformer but construction wise it is like a Slip Ring Induction Motor. The basic concept behind the VFT is a rotary transformer with three phase windings on both rotor and stator. A motor and drive system are used to adjust the rotational position of the rotor relative to the stator, thereby controlling the magnitude and direction of the power flowing through the VFT. VFT is a controlled bi-directional device allowing flow of power in both directions i.e. from one Grid to another and vice ...

There are two types of winding in a Conventional DC Motor, namely Filed Winding and Armature Winding. The purpose of Field Winding is to produce the working magnetic flux in the air gap and wound on the stator of the motor whereas armature winding is wound on the rotor. But in Permanent Magnet DC Motor or PMDC Motor, we do not use field winding rather permanent magnet is used to have the working flux in the air gap. The construction of rotor of PMDC is same as that of the Conventional DC Motor i.e. rotor of PMDC Motor consists of armature core, armature winding and commutator. Stationary Carbon Brushes are kept pressed on the commutator as in conventional DC motor. PMDC Motors are extensively used in automobiles for windshield wipers and washers, for blowers used in air conditioner and heaters, to raise and lower windows, in personnel computers disc drives etc. As millions of automobiles are manufactured per year, PMDC motors are also produced in millions. Maximum power rating...

What is SATACOM? STATCOM or Static Synchronous Compensator is a power electronic device using force commutated devices like IGBT, GTO etc. to control the reactive power flow through a power network and thereby increasing the stability of power network. STATCOM is a shunt device i.e. it is connected in shunt with the line. A Static Synchronous Compensator (STATCOM) is also known as a Static Synchronous Condenser (STATCON). It is a member of the Flexible AC Transmission System (FACTS) family of devices. The terms Synchronous in STATCOM mean that it can either absorb or generate reactive power in synchronization with the demand to stabilize the voltage of the power network. Working Principle of STATCOM: To understand the working principle of STATCOM, we will first have a look at the reactive power transfer equation. Let us consider two sources V1 and V2 are connected through an impedance Z = Ra + jX as shown in figure below. In the above reactive power ...