Photoelectric devices typically contain solid-state output switches. A solid-state switch has no moving parts (contacts). A solid-state switch uses a triac, SCR, NPN (current sink) transistor, or PNP (current source) transistor output to perform the switching function. See Figure 1. The triac output is used for switching AC loads. The …

Read More »## Single Phase Motors Characteristics

This article covers Characteristics of several Single Phase Electric Motors such as Shade Pole Motor, Split-Phase, and Capacitor Start-Induction Run (CSIR) Motors, Permanent Split Capacitor (PSC) and Capacitor Start-Capacitor Run (CSR) Motors, and Brushless D.C Motors in detail. Shaded Pole Motors (SP) Shaded Pole motors exhibit low starting and operating torque; they are …

Read More »## Three-Phase Induction Motor Torque-Speed Characteristics

Similar to other types of electric machines, a three-phase induction machine can work as a generator and as a motor. For this machine, however, because the stator must be connected to the three-phase circuit, the difference between being a motor or functioning as a generator lies in the speed of …

Read More »## Electric Power Distribution System Basics

A one-line diagram for an electric power distribution system is an electrical drawing that uses single lines and graphic symbols to illustrate the current path, voltage values, circuit disconnects, fuses, circuit breakers, transformers, and panelboards. One-line diagrams use the most basic symbols because the intent of the drawing is to …

Read More »## Distribution Switchboard | Panelboard | Function & Components

Electrical power is delivered to industrial, commercial, and residential buildings through a distribution and transmission system. Once the power is delivered to a building, it is up to the building electrician to further distribute the power to where it is required within the building. Switchboard Definition A switchboard is a …

Read More »## Electrical Power: Transmission & Distribution | Distribution Substation Components

Today, most electrical power is distributed through a network of transmission lines (conductors), substations (transformers), and generating equipment from relatively large, centralized power-generating stations directly to the customer. These large, centralized power-generating stations are located near abundant energy sources such as coal, oil, and natural gas. Large, centralized power-generating stations …

Read More »## Thevenin’s Theorem | Thevenin Equivalent Circuit | Solved Examples

Suppose that the circuit of Figure 1(a) is sealed in a black box (represented by the thick line) with only the terminals A and B exposed. A high-resistance voltmeter connected across these terminals shows that the open-circuit output voltage of the circuit is 80 V. Similarly, connecting a very low …

Read More »## Nodal Analysis with Solved Examples

Nodal analysis is a circuit-analysis format that combines Kirchhoff’s current- law equations with the source transformation. Converting all voltage sources to equivalent constant-current sources allows us to standardize the way we write the Kirchhoff’s current-law equations. For nodal analysis, we consider source currents to flow into a node. If the …

Read More »## Mesh Current Analysis with Solved Problems

Mesh Current Analysis is a technique that simplifies and speeds up writing the simultaneous equations for solving various resistance networks. The format for mesh equations is straightforward, but it cannot handle some of the networks that we can solve with the loop procedure. A mesh is a closed loop that …

Read More »## Source Transformation Example Problems with Solutions

Source transformation is a circuit analysis technique in which we convert voltage source in series with resistor into a current source in parallel with the resistor and vice versa. For a given constant-voltage source, Rint in the equivalent constant-current source has the same value but appears in parallel with the ideal current source, …

Read More »## Series-Parallel Circuit: Definition & Examples | Series-Parallel Resistors

Considered as a whole, the circuit in Figure 1 is neither a series nor a parallel circuit. However, R2 and R3 are connected between the same two points in the circuit and must have the same voltage drop. Therefore these two resistors are in parallel, and we can calculate a …

Read More »## Parallel Circuit: Definition & Examples | Resistors in Parallel

Figure 1 shows two different ways of drawing a circuit diagram for the same simple parallel circuit. Circuit diagrams usually show interconnecting conductors as either horizontal or vertical lines, as in Figure 1(a). However, to illustrate the nature of a parallel circuit, we redraw the circuit diagram by combining the …

Read More »## Series Circuit: Definition & Examples | Resistors in Series

Series Circuit Definition A series circuit can be identified by the connection between components or by the current through them. For example, in the circuit of Figure 1, R1 and R2 are connected in series because no other component or branch is connected to the junction of R1 and R2. …

Read More »## Power & Efficiency: Definition, Unit, Formula, Examples

Power is the rate of doing work. The letter symbol for power is P. The watt (W) is the Si unit of power. One watt is equal to one joule per second: 1 W = 1 J/s Equation 1 shows the relationship between power and work: \[\begin{matrix} P=\frac{W}{t} & {} …

Read More »## Linear & Nonlinear Resistor | Definition | Characteristic Curve

For most conductors, a graph of current versus voltage is a straight line, indicating a constant resistance (see Figure 1). The smaller the resistance, the steeper the slope of the graph. Definition: A resistor that maintains a constant V/I ratio is a linear resistor. As the current through a resistor …

Read More »## Three-Phase Electricity Explained

In Figure 1 a single load connected to a source constitutes a simple circuit. The source is represented by a winding because all generators have windings in them. Figure 1 A single circuit consisting of a source and a load. Figure 2 illustrates three of these assumed AC circuits near each other. Intentionally, the generators …

Read More »## Parallel RLC Circuit: Analysis & Example Problems

In parallel RLC circuits the three basic components are in parallel with each other, and, therefore, all are subject to the same voltage. The current for each branch, however, depends on the impedance of the branch and can be individually determined by employing Ohm’s law. For a parallel RLC circuit, the voltage is common …

Read More »## Series RLC Circuit: Analysis & Example Problems

In a series RLC circuit, the three basic elements are in series with each other, which means that they all have the same current. The formulation covers the general case of three types of the load being present in a circuit. If any of the components is absent (usually, the inductor or …

Read More »## Capacitors in AC Circuits

When a capacitor is subject to a voltage across its terminals, it starts charging until its charge becomes at the level of the applied voltage. During the time that charging takes place a current flows in the circuit (wires connecting the capacitor to the power source). This current is due to …

Read More »## Inductors in AC Circuits

When a coil of wire (an inductor) is connected to DC electricity (Figure 1), a current is building up from zero, making a magnetic field. The wire, itself, is in that field, and therefore, a voltage is generated in it. This generated voltage is in the opposite direction of the …

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