Author: John Mulindi
-
Sweep Frequency Generator: Function, Features & Applications
Function & Features of a Sweep Frequency Generator A special type of signal generator which generates a sinusoidal output whose frequency is automatically varied or swept between two chosen frequencies is referred to as sweep frequency generator. One complete cycle of the frequency variation is termed as a sweep. The rate at which the frequency…
-
Switchgear Terminology & IEC Standards
Switchgear generally refers to the switching devices and their combinations, with the related control, measuring, protective and regulating equipment. The switchgear equipment basic purpose is switching and interrupting currents either under normal or abnormal operating conditions. Modern power systems, power lines and other apparatus operate at high voltages and carry large currents. When a short…
-
Electron/Vacuum Tubes vs. Semiconductor Devices
Electronic circuitry has undergone tremendous changes since the advancement of a triode, a type of electron tube that consists of three elements namely filament, grid and plate. In a triode, the amount of current from the cathode to the plate (i.e. controlled current is a function of both the grid to cathode voltage (the controlling…
-
Fault Protection & Diagnostics in Power ICs using Temperature Sensors
Fault conditions sensing for example, the detection of a short circuit is an integral part of many smart power integrated circuits (ICs)/power ICs. The ability to get temperature sensors in the semiconductor process provides protection and diagnostics as part of the features of these devices. The main function of the power IC is to provide…
-
Voltage-Controlled Attenuator: Function, Features & Application
Function of a Voltage-Controlled Attenuator The function of a voltage-controlled attenuator is to produce an output signal vo(t) that is a variable fraction of the ac input signal vin(t). The process of reduction of the amplitude of a signal is called attenuation. Features of a Voltage-Controlled Attenuator Let’s consider a circuit of a voltage-controlled attenuator…
-
Microwave Active Devices: Types, Features & Operation
Generally microwave devices can be categorized as either passive components or active components. We have already talked about microwave passive components in this other article. This article focuses on microwave active devices. They may be classified into two types: low-power solid-state devices and high-power vacuum tube devices. Communications involving the gigahertz bandwidths cannot employ conventional…
-
Air-Blast Circuit Breakers: Features, Operation & Applications
Air-blast circuit breakers utilize a blast of compressed air typically at a pressure of 25–75 bar, which is directed across the path to cool and eliminate the ionized gas, in other words the air-blast is employed as the quenching medium. The air-blast cools the arc and sweeps away the arcing products to the atmosphere. This…
-
Testing & Commissioning Protective Schemes
Generally protective equipment testing may be divided into three stages: Factory and commissioning tests confirm the performance of equipment during its development and fabrication, and its operational environment. Periodical maintenance ensures that this performance is maintained. For example, the relay manufacturer must provide sufficient testing of protective gear before it is accepted and commissioned. The…
-
Digital Multimeter: Principle of Operation and How it is used
A Multimeter or volt-ohm-milliammeter (VOM) is an instrument used to measure current, voltage, and resistance. It can be used for measuring dc as well as ac voltages and currents. The two common types of multimeters include the analog multimeter and the digital multimeter. Analog multimeters employs a moving pointer mechanism that swings a long a…
-
The Principles of Power System Protection
The Function and Principles of Power System Protection The objective of power system protection is to detect faults or abnormal operating conditions and initiate corrective action. Principles of Power System Protection There are different principles used in accomplishing power system protection, we have discussed them in the following sections: Discrimination by Time In simple radial…