An RCIM sensor is a sensor that results in a change in electrical resistance, capacitance, inductance, electrical field, or magnetic field when it is exposed to a physical, chemical, or biological stimulus. Its output could be a voltage, current, electrical charge, time, or frequency to reflect these changes. Following are the most important characteristics of […]
For supplying a load in excess of the rating of an existing transformer, another transformer is usually connected in parallel with it since replacing it with a single larger unit is a costly alternative. The cost of a spare smaller rating transformer is also lower. Also, it is preferable to have a parallel transformer in
Printed circuit boards are the building block of most modern electronic devices. They are created to provide mechanical and electrical support for the components. Compared to traditional circuits, printed circuit boards have many advantages. For instance, they are small and light, making them suitable for many modern devices. In addition, the low cost of production
Overheating is a major cause of insulation and bearing failure. 3 phase motor overheating reasons are as under: Line-Caused Motor Overheating Reasons There are four causes of line-caused overheating: overvoltage, low voltage, unbalanced voltage, and a high-resistance connection. Overvoltage: Overvoltage can cause a normally loaded motor to overheat. NEMA standard specifications allow motors a voltage
Encoders are non-contact, optical-based digital devices that are used for measuring displacement. They can be used to measure both linear and rotary displacement. We will concentrate on rotary-type encoders, which are widely used in motion-control applications. Rotary encoders are available as incremental or absolute type. An incremental encoder measures changes in rotation from some datum
An encoder is a sensor that converts rotational or linear displacement into digital signals. As shown in Figure 1, a typical optical encoder consists of: (1) light source (LED), (2) code disk, (3) stationary mask, (4) light detector (photodetector), and (5) signal conditioning circuit. The disk sits between the light source and the photodetector. As
The relay operation is a function of the input quantities, such as current, voltage, impedance, and/or phase angle. The relay can be made to respond to either a single quantity or a combination of two or all input quantities. When the relay is operated by a single quantity, its response is strictly a function of
Instrument transformers are essential parts of many electrical metering and relaying systems. The quality of instrument transformers will affect directly the overall accuracy and performance of these systems. Instrument transformer performance is critical in protective relaying since the relays can only be as good as the instrument transformers. They serve two basic functions: To change
The main tests that are conducted on instrument transformers are as follows: Polarity Test of Instrument Transformers Instrument transformers are marked to indicate the instantaneous direction of primary and secondary currents. Usually, one primary and one secondary terminal are marked with a cross (×) or a dot (•) or a square (■) to indicate the
A perfect cable can be electrically modeled by a single capacitor. The longer the cable, the larger the capacitance of this capacitor. As the insulation of the cable degrades, losses in this capacitor increase which can be measured by tan delta testing of the cable. The measurements can be compared with previous test measurements and