Electrical4U What are T Parameters? T-parameters are the ABCD (transmission) parameters of a transmission line two-port, also written as ABCD parameters of a two-port network. Port-1 is the sending end. Port-2 is the receiving end. For that two-port, the T-parameter equations are \begin{equation} V_S=AV_R + BI_R \end{equation} \begin{equation} I_S=CV_R + DI_R \end{equation} Where VS = sending-end … Read more
What is a Filter Bank? In image or signal processing, a filter bank is a set of bandpass filters that split one input into analysis signals, each occupying one frequency sub-band of the original. Two-channel wavelet banks are one class of filter bank: they generate a scaling function and wavelets. The figure below is the … Read more
What is Power Factor Correction? Power factor correction (PFC) raises the power factor of an AC circuit by cancelling some of the reactive power. For a given kW, that cuts the current drawn from the supply and the ohmic loss in feeders. Shunt capacitors and over-excited synchronous motors supply leading vars that cancel lagging vars … Read more
What is Thevenin’s Theorem (Thevenin Equivalent)? Thevenin’s theorem (Helmholtz–Thévenin) says a linear network of voltage sources, current sources and resistances, seen from two load terminals, equals one voltage VTh in series with one resistance RTh. That pair is the Thevenin equivalent. Linear dependent sources are allowed. Nonlinear devices are not, except as a small-signal linearization. … Read more
What is Open Circuit Voltage? Open-circuit voltage is the potential between two terminals with no load connected, so no current leaves those terminals. Call that the voltage of an open circuit at that pair of nodes. In linear network analysis it is the Thevenin Voltage. Symbols: OCV or VOC. With the load off those terminals, … Read more
What is an Open Circuit? An open circuit is a break in an electric circuit so there is no complete loop. Current in that path is zero. A closed circuit is the opposite: a complete path. An open switch, a cut wire or a loose terminal are everyday opens. The two sides of the break … Read more
What is a Wound Rotor Induction Motor? A wound-rotor induction motor (also called a slip-ring motor, not a “would round” motor) is a three-phase induction machine. External resistance in the rotor circuit raises starting torque and limits starting current. Other names are phase-wound motor and slip-ring induction motor. Like any induction motor it runs below … Read more
What is CSST Bonding? CSST (corrugated stainless-steel tubing) bonding is a jumper from the metal gas piping to the building grounding-electrode system. That jumper gives a low-impedance path so nearby metal stays nearer the same potential in a lightning event. Yellow (standard) CSST makers require this extra bond. Arc-resistant (often black) CSST may follow a … Read more
What is a 1900 Electrical Box? A 1900 box is a 4-inch (4’’) square metal outlet box, also called a 4-square. The old catalogue name was a combination gas-and-electric fixture box, and that number stayed as trade slang. Today the box is electrical only and gives more room than a single-gang switch box. Makers sell … Read more
What is a Cut Sheet? A cut sheet (also called a spec sheet or specification sheet) is a maker’s one- or few-page data sheet for one product. It lists ratings, sizes, options and features. Electricians and designers use them for motors, circuit breakers, and transformers. On many commercial jobs the designer or owner reviews product … Read more