Electrical4U 
What is Medium Transmission Line? A medium transmission line is a transmission line model that includes shunt charging current but represents the parameters as lumped elements. Length from 80 km to 250 km is one teaching convention, not a universal boundary. A short transmission line may neglect shunt capacitance, while long transmission lines use distributed … Read more
A Junction Field Effect Transistor (JFET) is a depletion-mode field-effect transistor whose reverse-biased gate-channel p-n junction controls a conducting channel. N-channel and p-channel devices use opposite carrier types and voltage polarities. MOSFETs are another common field-effect transistor family.Engineers describe a JFET as voltage controlled because gate-source voltage sets channel depletion and drain current. Channel current … Read more
What is a Synchronous Motor? A synchronous motor is an AC machine whose rotor turns in step with the stator’s rotating magnetic field during steady operation. Mechanical speed is related to electrical frequency through the number of poles. This operating principle distinguishes a synchronous motor from an induction motor, whose rotor requires slip to produce … Read more
Electric flux is defined as the total number of electric lines of force emanating from a charged body. An electric field is represented by electric flux. Unlike magnetic flux, electric flux lines are not always closed loops. This is because an isolated magnetic north pole or an isolated magnetic south pole does not exist practically, … Read more
What is Long Transmission Line? A long transmission line uses a distributed-parameter model for a transmission line. A length greater than 250 km (150 miles) is one teaching convention, not a universal boundary. Unlike short transmission lines and medium transmission lines, the long-line model represents series impedance and shunt admittance continuously along the route. Its … Read more
What is Power Factor? Power factor (PF) is the ratio of active power P, measured in watts or kilowatts, to apparent power S, measured in volt-amperes or kilovolt-amperes. It shows how much source and conductor capacity is required for the transferred active power. Its magnitude is from 0 to 1. Some meters use a signed … Read more
Type tests, routine tests and special tests confirm the specification and performance of an electrical power transformer. Some of those tests are done at the manufacturer’s premises before the transformer is delivered. Transformer manufacturers run two main factory groups: type tests on a representative unit and routine tests on every unit. Some transformer tests are … Read more
What is Short Transmission Line? A short transmission line is a transmission line model that neglects shunt capacitance because charging current has little effect on the required calculation. Length below 80 km or voltage below 69 kV are common teaching guides, not universal limits. medium transmission lines include lumped shunt admittance, while long transmission lines … Read more
What is Ferranti Effect? The Ferranti effect is the rise in voltage from the sending end to the receiving end of an energised long transmission line. It occurs under no-load or light-load conditions, when the receiving-end voltage can exceed the sending-end voltage. Engineers express the rise as a voltage ratio or percentage. Under normal load, … Read more
Transient rotor-angle stability is the ability of interconnected synchronous machines to remain in synchronism after a severe disturbance, such as a short circuit, line trip or rapid change in generation or load. A fault changes electrical power transfer and can cause machines in the power generation system to accelerate or decelerate relative to one another.First-swing … Read more