$latex \Rightarrow &s=2 &bg=ffffff$ The steady state stability limit is defined as the maximum power that can be transmitted to the receiving end without loss of synchronism. $latex \displaystyle P_m - P_e = M \frac{d^2\delta}{dt^2} &s=2 &bg=ffffff$ All quantities are in Per Unit $latex \displaystyle P_e = P_{max} sin(\delta) &s=2 &bg=ffffff$ $latex \Rightarrow &s=2 &bg=ffffff$ Let the system be … Continue reading Steady State Stability Analysis

# Category: Power System Analysis

# Swing Equation

$latex \Rightarrow &s=2 &bg=ffffff$ The problem of stability can understand electrically as well as mechanically if there is an imbalance between mechanical input torque and electrical output torque, the rotor will either accelerate or deaccelerate. Accelerating Torque $latex \rightarrow &s=2 &bg=ffffff$ $latex T_a = T_m - T_e &s=2 &bg=ffffff$ $latex \displaystyle T_m - T_e = J \frac{d^2 \theta}{dt^2} &s=2 … Continue reading Swing Equation

# Ferranti Effect

A long transmission line draws a substantial quantity of charging current. If such a line is open circuited or very lightly loaded at the receiving end, the voltage at the receiving end may become higher than the voltage at the sending end. This is known as Ferranti effect. $latex \Rightarrow &s=2 &bg=ffffff$ Ferranti effect will occur … Continue reading Ferranti Effect

# Optimum placing of an Intersheath

Now let us consider a cable with one intersheath only. Let r = Radius of core or conductor R = Overall radius r1 = Radius of intersheath Let V1 = Potential difference core and Intersheath V2 = Potential difference between Intersheath and lead sheath. To find the optimum placing of an intersheath > … Continue reading Optimum placing of an Intersheath

# Economical Core diameter

In practice, the maximum stress value should be as low as possible. When the voltageV and sheath diameter D are fixed, the only parameter to be selected is the core diameter d. So d should be selected for which gmax value is minimum. The value of gmax , will be minimum when ∂gmax / ∂d = 0 For high … Continue reading Economical Core diameter

# Capacitance Grading

The grading done by using the layers of dielectrics having different permittivities between the core and the sheath is called Capacitance grading. In intesheath grading, the permittivity of dielectric is same everywhere and the dielectric is said to be homogeneous. But is case of capacitance grading, a composite dielectric is used. Let d1 = Diameter of … Continue reading Capacitance Grading

# Intersheath Grading

In this method of grading, in between the core and the lead sheath number of metallic sheaths are placed which are called intersheats. All these intersheaths are maintained at different potentials by connecting them to the tappings of the transformer secondary. These potentials are between the core potential and earth potential. Generally lead is used … Continue reading Intersheath Grading

# Grading of Cables

We have seen that the stress in the insulation is maximum at the conductor surface and minimum at the sheath. To avoid the breakdown of the insulation , it is necessary to have uniform distribution of stress all along the insulation. Practically some methods are used to obtain uniform distribution of stress. The process of … Continue reading Grading of Cables

# Stress in Insulation

The electric stress in insulation is the electric field intensity acting at any point P in insulation. The stress is maximum at the surface of the conductor i.e. when x = r. Similarly the minimum stress will be at the sheath i.e. x = R hence, The variation of stress in the electric material … Continue reading Stress in Insulation

# Capacitance of a Single Core Cable

A single core cable is equivalent to two co-axial cylinders. The inner cylinder is conductor itself while the outer cylinder is the lead sheath. The lead sheath is always at earth potential. Let d= Conductor diameter D = Total diameter with sheath The co-axial cylindrical form of cable and its section are shown in the … Continue reading Capacitance of a Single Core Cable