Power in AC Circuit The instantaneous power of an AC waveform is given by p(t) = v(t) · i(t) Power in a Resistance The current and voltage are in phase on the resistor (Fig. 1). For a sinusoidal voltage, the instantaneous power is Here V and I are the RMS values of the voltage and …
Generally, it can be stated that a circuit breaker is intended to protect the electrical conductors in the circuit from overheating. It can also be stated that the equipment grounding conductor (EGC) is required by the NEC to be connected so that a low impedance fault current path is provided for the main purpose of …
Molded Case Circuit Breakers or MCCB circuit breakers are black plastic–cased automatic switches. They are designed to primarily protect insulating materials from overheating. Molded case circuit breakers (MCCB) are by far the most commonly used breakers in residential, commercial, and industrial facilities. When an MCCB has opened (or “tripped”) to protect the circuit, it can …
The term “power factor” (PF) is an expression of the relationship between the peak voltage and the peak current. Stated differently, the power factor is an expression of how far out of phase the voltage and current are to each other. What is power factor? Figure 1 shows both voltage and current peaks occurring at …
The fuse provides protection by melting away a thin metal link in the faulted circuit. The metal link may be of silver, copper, or nickel, silver being more common for long-term performance stability. The fuse body is generally filled with a sand-type filler (Figure 1) to suppress sparks when the fuse link melts and interrupts the …
Thevenin’s theorem is very useful in solving electrical networks which may not be easily solved by other methods. In this article, I will discuss this theorem and show some of the thevenin theorem examples to make this theorem easily understandable. Thévenin’s theorem is a circuit analysis technique that reduces any linear bilateral network to an equivalent …
The Kirchhoff’s Laws are very useful in solving electrical networks which may not be easily solved by Ohm’s Law. In this article, I will describe the Kirchhoff’s current law and will show some kirchhoff’s current law examples to make this law easily understandable. Kirchhoff’s current law states the following: The summation of currents entering a node …
The superposition theorem is a method that allows us to determine the current through or the voltage across any resistor or branch in a network. The advantage of using this approach instead of mesh analysis or nodal analysis is that it is not necessary to use determinants or matrix algebra to analyze a given circuit. …
Latching relays typically use a mechanical latch or permanent magnet to hold the contacts in their last energized position without the need for continued application of coil power. They are especially useful in applications where power must be conserved, such as a battery-operated device, or where it is desirable to have a relay stay in …
Timer relays are a variation of the standard instantaneous control relay in which a fixed or adjustable time delay occurs after a change in the control signal before the switching action occurs. Timers allow a multitude of operations in a control circuit to be automatically started and stopped at different time intervals. The use of …
