Electrical4U 
After installation of power transformer, several pre-commissioning tests must be performed before putting the transformer into service. Additionally, various instruments associated with the transformer should be checked. Common Pre-commissioning Tests of Transformer Insulation resistance values of various winding should be checked. During measurement of insulation resistance, the transformer must not be connected with any external … Read more
The order of a control system is determined by the power of ‘s’ in the denominator of its transfer function. A control system is classified as second order when the highest power of ‘s’ in the transfer function’s denominator is 2. The general expression of the transfer function of a second order control system is … Read more
Let’s discuss the simplest way to draw the phasor diagram for a synchronous motor and its advantages. First, we need to understand the notations for each quantity:Ef to represent the excitation voltageVt to represent the terminal voltageIa to represent the armature currentΘ to represent the angle between terminal voltage and armature currentᴪ to represent the … Read more
In this article we discuss one of the easiest methods of making a phasor diagram for a synchronous generator. Now, let’s list all the notations in one place to clarify the phasor diagram. In this diagram, we use: To draw the phasor diagram, we use Vt as the reference point. Consider the following two important … Read more
AC series motors are also known as the modified DC series motor as their construction is very similar to that of the DC series motor. Before we discuss these modifications, here it is essential to discuss what is the need and where do we need to do modifications. In order to understand this, consider this … Read more
We will discuss here the simplest way of drawing the phasor diagram for an AC series motor. Before we draw phasor diagram, let us write the various notations for each quantity at one place. Here we will use:Rs to represent the resistance of the series fieldRp to represent the resistance of the inter pole circuitRc … Read more
In order to derive various conditions for power in both alternators and synchronous motors, let us consider the general problem of power flow through inductive impedance. The circuit diagram shown below consists of voltage source E1, voltage source E1 and load which consists of one resistor in series with an inductor. Now if we assume … Read more
What is a Block Diagram in a Control System? A block diagram is used to represent a control system in diagram form. In other words, the practical representation of a control system is its block diagram. Each element of the control system is represented with a block and the block is the symbolic representation of … Read more
A signal flow graph of a control system is a simpler version of a block diagram. It replaces blocks, summing symbols, and take-off points with branches and nodes.The transfer function is referred as transmittance in signal flow graph. Let us take an example of equation y = Kx. This equation can be represented with block … Read more
Various routine tests are performed for ensuring the quality, performance of a circuit breaker and these are Let us discuss them one by one. Power Frequency Over Voltage Withstand Test Power system can experience temporary overvoltage conditions due to various reasons, like sudden load changes or incorrect tap changer operations. The power frequency over voltage … Read more