A Website on Maintenance of Electrical Systems

  A Variable Frequency Drive (VFD) is an electronic device that vary the frequency and voltage of the power supplied to an electric motor to alter the speed and torque of the electric motor.  The primary purpose of a most VFDs is to adjust the speed of the motor to match process requirements. For example, in a gas processing plant there are various aftercooler fans driven by VFD-fed motors, the VFD increases or decreases the speed on the cooler fan in response to the process variable setpoint.  In this case, the temperature of the gas to be cooled is the process variable. HOW A VFD WORKS A VFD works in three stages namely, Rectifier Stage, DC bus and Inverter stage. In the rectifier stage , AC supplied to the VFD is converted to DC using diodes. The output from the rectifier is a pulsating DC. The Pulsating DC is smoothened out in the DC bus stage using capacitors and/or inductors. The Filtered DC from the DC Bus supplies electrical energy to the inverter stage of the VF...

Dual Speed Motor   Dual speed motors, also known as two-speed motors, are electric motors designed to operate at two distinct speeds. Most of these motors typically achieve their dual-speed capability through Pole-changing motor they also known as Dahlander motors because they were created by  Robert Dahlander (1870–1935). l Principle of operation. A  regular induction motor. works on the principle of electromagnetic induction where the alternating current passing through the stator winding induces a rotating magnetic field. This magnetic field then induces a current in the rotor winding, causing it to rotate and generate torque. The rotor of the induction motor rotates because it tries to catch the rotating magnetic field (Ns) generated in the stator. It can never catch this magnetic field because of the slip and it turns chases this field until power is removed from the stator coils and the rotating magnetic field disappears. The speed of the rotor depends on the speed ...

  A battery is a collection of one or more electrochemical cells that converts chemical energy contained within its active materials directly into electric energy. Many types of batteries are commonly used in modern day applications, and they are named by the elements that make up the electrochemical cell of the battery they include  1) Nickel Cadmium (Ni-Cd) 2) Lithium Ion (Li-Ion) 3) Nickel-Metal Hydride (NiMH) 4) Lead Acid The lead-acid battery was the first rechargeable battery created by Gaston Planté in 1859 it uses  lead and sulphuric acid to function. The lead is submerged into the sulphuric acid and controlled chemical reaction creates voltage potential. Components of an Electrochemical cell Anode: Oxidation occurs at the anode Cathode: Reduction occurs at the cathode. Electrodes: In order to hook up an external circuit you need have something to physically connect the wire to. There are two types of electrodes, active and inert. An  Inert electrod...

 In this article, we'll delve into the world of enclosure ratings, exploring hazardous area classification, explosion-proof ratings, and ingress protection ratings. From my experience in the industry i found out that there is some confusion in the minds of a few people in the industry they think that  Ingress Protection (IP) ratings-specifying the environmental protection the enclosure provides is also a  system of hazardous area classification  and an equipment classified for use in hazardous areas is automatically explosion proof.  My understanding is that they are not interchangeable, and we are going to delve deep into each of them. before we begin take a look at the image below to give you a broad understanding. Hazardous Area Classification: This is focused on clearly defining the risk zones . A hazardous area is a location within a petrochemical /gas processing plant or some other equally volatile plant an explosive atmosphere may form due to the presence...