A transformer ratio-arm bridge circuit is used as shown in the simplified diagram of Figure1. The circuit consists of a standard reference capacitor (CS) and the insula- tion under test (CX). A special multiwinding transformer is the characteristic feature of the circuit. A voltage is applied to bothCSandCX. The ratio arms, NSandNXare adjusted to balance capacitive current, and the variable resis- tor (RS) is adjusted to
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balance resistive current. The null indicator is used to determine when the bridge circuit is balanced. The values ofNSandNXare used to determine capacitance and the value ofRScorrelates to power (dissipation) factor of the test insulation. Model CB-100 is a low voltage (LV) bridge which is manually balanced for both capacitance and DF, but it is direct reading. The semiautomatic models require manual balancing for capacitance, but they provide a direct digital readout of DF. Model Delta-3000 is automatic balancing for both capacitance and PF, and can also display DF directly (Figure 2). It is simple to operate, providing automatic balancing and digital display for voltage, current, dielectric loss (in watts), capacitance, and PF. Readings are adjusted to equivalent values of 10 or 2. 5 kV The formulas used for calculating the PF or DF are illustrated by using an example (Figure 3) with an insulation of PF = 1. 0%. The value of PF is given by the cosine of the q angle, or the equation can be written as For specific operating instructions for any Megger test set, the reader is advised to follow the instructions given in the appropriate test set operating manual. This section briefly describes the Doble Engineering Company test equip- ment, its theory, and operation for performing PF tests. The description of theory and operation is based on the MEU test set, but the theory and opera- tion of the other test sets is the same...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
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The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
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This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
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