The statements of Kirchhoff’s laws are shown in Art. For DC networks except that instead of algebraic sum of currents and voltages, we take phasors or vector sums for AC networks. 1. KIRCHHOFF’S CURRENT LAW: According to this law, in any electrical network, the phasors sum of the currents meeting
Year: 2015
Following are few characteristics of Moving Coil Meter Movement. (1) Full-scale deflection current (Im), (2) Internal resistance of the coil (Rm), (3) Sensitivity (S). 1. FULL-SCALE DEFLECTION CURRENT (IM) It is the current needed to deflect the pointer all the way to the right to the last mark on the
All instruments, whether electrical or electronic, are calibrated at the time of manufacture against a measurement standard. 1. INTERNATIONAL STANDARDS These are defined by international agreement and are maintained at the international Bureau of Weights and Measurements in Paris. 2. PRIMARY STANDARDS These are maintained at national standards laboratories in
Electrical isolation by means of transformers is needed in switch-mode dc power supplies for three reasons: SAFETY: It is necessary for the low-voltage dc output to be isolated from the utility supply to avoid the shock hazard. DIFFERENT REFERENCE POTENTIALS: The dc supply may have to operate at a different
There are several deleterious effects of high distortion in the current waveform and the poor power factor that results due to it. These are as follows: Power loss in utility equipment such as distribution and transmission lines, transformers, and generators increases, possibly to the point of overloading them. Harmonic currents
Power electronic converters are switch-mode circuits that process power between two electrical systems using power semiconductor switches. The electrical systems can be either DC or AC. Therefore, there are four possible types of converters; namely DC/DC, DC/AC, AC/DC, and AC/AC. The four converter types are described below: DC/DC CONVERTER: is
The concept of the ideal switch is important when evaluating circuit topologies. Assumptions of zero-voltage drop, zero-leakage current, and instantaneous transitions make it easier to simulate and model the behavior of various electrical designs. Using the characteristics of an ideal switch, there are three classes of power switches: UNCONTROLLED SWITCH:
The aim of power electronics is to optimize the power efficiency, minimal size, minimal weight and meeting the requirements for user loads by modifying the voltages and currents. Fig.1 shows a block diagram of a power electronic system. Power processors, depending on the application, the output of the load may
Stability is a notion that describes whether the system will be able to follow the input command, that is, be useful in general. In a non-rigorous manner, a system is said to be unstable if its output is out of control. To investigate the effect of feedback on stability, from
Feedback is used to reduce the error between the reference input and the system output. Feedback also has effects on such system performance characteristics as stability, bandwidth, overall gain, impedance, and sensitivity. Feedback affects the gain G of a non-feedback system by a factor of 1 + GH. The system
