Author: John Mulindi
-
Gamma Spectroscopy Measurement Technique
Gamma spectroscopy is a radiochemistry measurement technique that determines the energy and count rate of gamma rays emitted by radioactive substances. A detailed analysis of gamma ray energy spectrum is used to determine the identity and quantity of gamma emitters present in a material. The apparatus used in gamma spectroscopy includes a detector, a pulse…
-
Hierarchical Control Strategies for a Process Plant
In a process plant, we typically have a number of control goals that require different algorithms and types of information from the process; from the level closest to the process to the plant-wide control. All these activities ought to be connected; hence some kind of hierarchy is necessary. Local Control Local control uses information directly…
-
Permanent Magnet DC Motors – Operation & Applications
Permanent magnet dc motors employ a permanent magnet instead of stationary field winding (as with the case of some other types of dc motors) for producing the required magnetic flux. These stationary magnets are normally fixed to the outer shell of the motor as illustrated in Figure 1.0. Features of a Permanent Magnet DC Motor…
-
Passive vs. Active Sensors
Sensors are normally used to convert physical variables like pressure to signal variables. Sensors are also often termed to as transducers since they are devices that convert input energy of one form into output energy of another form. Sensors can be classified into two broad classes depending on how they interact with the environment they…
-
Principle of Operation and Applications of a Laser Diode
Laser diodes are PN junction devices under a forward bias. LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. Laser Diode Structure The laser diode structure can be divided into two categories: An example of an edge-emitting laser diode structure is shown in Figure 1.0 below. This type of structure is termed…
-
Features of Optical Modulators in Telecommunication Systems
Light emitting PN junction devices such as LEDs and laser diodes are easily modulated by superimposing signals on to the injected current. This is direct modulation. Laser diodes in high-bit rate and long-span optical communication systems are often used under direct modulation. The downside of direct modulation is that, it results in chirping which limits…
-
How to Perform a Brake Test on a DC Motor
Testing is usually performed on DC machines to establish efficiency and power losses. A brake test is a direct technique that involves applying a brake to a water-cooled pulley mounted on the motor shaft as demonstrated in Figure 1.0. This brake test method is typically used on small motors. The brake band is fixed with…
-
Transformer Substations in an Electric Power Supply System
The greater part of the substations in the power systems are focused on changing of the voltage level of the electric supply. These are termed to as transformer substations since the transformer is the key component used to change the voltage level. Transformer substations may be classified further into the following substations depending on the…
-
How the Photoelectric Effect Influences Semiconductors
A photoelectric effect is any effect in which light energy is converted to electricity. When light strikes certain light-sensitive materials, it may cause them to give electrons or change their ability to conduct electricity or may cause them to develop an electrical potential or voltage across two surfaces. When a surface is exposed to electromagnetic…
-
Features and Classification of Substations
A substation can be defined as an assembly of apparatus used to change some characteristics like voltage, AC, DC, frequency, power factor, etc., of electric supply. Substations play a key role in power systems. The continuity of supply depends largely upon the successful operation of substations. Thus, it is imperative to exercise utmost care while…