Electrical4U 
A transfer function is the Laplace ratio of a linear control system output to its input, taken with all initial conditions at zero. A block diagram draws that ratio as a block. Arrows carry the input and output signals. The reference input (the excitation or cause) passes through that transfer function and becomes the controlled output … Read more
What is a Nyquist Plot? A Nyquist plot is a polar or Cartesian graph used in control engineering and signal processing to judge closed-loop stability from an open-loop transfer function G(jω). In Cartesian form the real part of G(jω) is X and the imaginary part is Y. Frequency ω is the parameter along the curve. … Read more
An electrical motor becomes a servo motor only when a servomechanism closes the loop around it. A DC motor used that way is a DC servo motor. Among types of DC motor you will see a shunt wound DC motor, a series DC motor, a separately excited machine, a permanent magnet DC motor and a … Read more
An electrical circuit breaker makes and breaks current-carrying contacts under load, overload or fault. Operating time on close is counted from the close-coil current to first contact touch. Tripping time on open is counted from the trip-coil current to arcing-contact part. A circuit breaker sits closed for most of its life and only rarely travels. … Read more
Boiler feed water treatment strips dissolved salts, silica, suspended solids and dissolved gases from make-up so tubes do not scale or corrode. Natural sources all carry some of those loads; how much depends on the catchment.Why it is necessary to treat the raw water?Untreated raw water will deposit hardness salts on the boiler.Because- That is … Read more
Prospective short-circuit current is set by the source and the impedance up to the fault, not by the circuit breaker (CB). While that current still flows through a closed CB, the poles take thermal I2t heating and electrodynamic force. The formulas below estimate those stresses from a known short-circuit current. If the conducting parts are … Read more
Multimeters, as the name suggests, are instruments used to measure multiple electrical quantities. The most basic analog multimeter measures voltage, current and resistance, often referred to as an AVO meter (Amperes, Volts, Ohms). There are two types of multimeters: analog and digital multimeter. This article focuses on analog multimeters. An analog multimeter is a PMMC … Read more
Vacuum switchgear interrupts in a sealed vacuum bottle rather than in gas or oil. In medium voltage switchgear the usual voltage window is 3 to 36 kV. On that band vacuum now outsells air, SF6 and oil for new indoor boards, because a vacuum circuit breaker copes with frequent fault and load switching with little … Read more
A 3 kV to 36 kV switchgear system is classed here as medium voltage switchgear or MV switchgear. IEC practice can run MV from 1 kV to 52 kV, so this band is a common indoor and outdoor range rather than the only definition. These switchgears come as metal enclosed indoor type switchgear, metal-enclosed outdoor … Read more
Armature reaction is the armature mmf acting on the main field. At no load the magnetic neutral axis sits on the geometrical neutral axis, so the brushes sit there too. On load the armature flux lies along the interpolar axis and looks roughly triangular. That brush-axis mmf cross-magnetizes the main field. Flux crowds at the … Read more