Voltmeters and Ammeters are used to measure the voltage and current in the circuits. Using instrument transformers, ranges of these devices to measure can be increased. A current transformer is basically a step-down transformer; hence it steps down the current. When used in conjunction with the low range ammeter, a current transformer (CT) increases the range … Read more
The operation of moving coil meters depends on the electromagnetic effect of the current (a force is exerted on the current carrying conductor when placed in a magnetic field). Moving coil instruments are of two types Permanent magnet type Dynamometer type Permanent magnet type moving coil instruments can be used only in dc circuits whereas … Read more
Advantages of PLCs 1. Higher Reliability Once the program was written and tested it can be easily downloaded into other PLC’s memory. It requires lesser and simpler wiring compared to conventional hard-wired circuits employed. Hence reliability of the system increases significantly with PLCs. 2. More Flexibility It is easier to create a new program module … Read more
Programmable Logic Controllers (PLCs) have basic architecture compared to normal general purpose computers. A normal computer can be converted to PLCs by providing a way that the computer can able to receive information or signal from the field devices such as push buttons, switches and valve positions. The computer requires some software to process the information … Read more
Applications of SCADA SCADA (Supervisory Control and Data Acquisition) systems have a wide range of applications. SCADA technology is widely used where the process systems spread in the wide range of area away from the control center. These process system applications require control, monitor and frequent intervention for better operation of the system. In these … Read more
Master Terminal Units (MTU) role Master terminal units (MTU) in SCADA system is a device that issues the commands to the Remote Terminal Unit (RTUs) which are located at remote places from the control, gathers the required data, stores the information, and process the information and display the information in the form of pictures, curves … Read more
Constant Voltage Transmission Voltage in a long distance transmission line drops from sending end to receiving end due to the presence of line losses in the system ( except on no-load conditions). Voltage regulation and power handling capability are two important features of the transmission line for delivering the power. The voltage of the transmission … Read more
For transmission of more power for long distances to load centers, Extra High Voltage (EHV) transmission is employed. Implementing EHV has an advantage of the reduction in the copper losses and improves efficiency. However, transmission of voltage beyond 300kV will pose some problems such as Corona effect which causes significant power loss and interference with … Read more
Insulation materials used in transformers and motors are classified based on the temperature withstand capability. Some of the insulation classes used in transformers and induction motors are: Class Y, Class A, Class E, Class B, Class F, Class H and Class C. Class Y Maximum hot spot temperature for this type of insulator is 90°C. … Read more
When a transformer is energized after a short interruption, the transformer may draw high inrush currents from the system due to core magnetization being out of synch with the voltage. The inrush currents will be as high as short-circuit currents in the transformer (almost 20 to 40 times the rated normal full load current of … Read more