It is usually associated with system faults but can also be caused by energization of heavy loads or starting of large motors.
Voltage sag is the short reduction in the RMS voltage between 0.1 to 0.9 pu for a duration of 0.5 cycle to 1 minute
Bus Type - Known Parameter - Unknown Parameter
Load Bus -P, Q - V, phase angle
Generator Bus - P, V (magnitude) - Q, Voltage phase angle
Slack Bus Voltage - magnitude and phase angle - P, Q
The ratio of full load current to short circuit current = 1/5
Xsc = j/(1/5)
External reactance required = j*((1/5) - 0.05))
= j*0.15 pu
Full load current = (30*1000)/(√3*11)
= 1574.6 A
Per unit reactance = j*0.15 = (I*Xr)/V
j*0.15 = (1574.6*Xb)/((11/√3)*1000))
= 0.60 ohm
φ is firing angle
Voltage ripple for 3-phase bridge rectifier = cos(φ) = Cos(30)
Thermistors are ideal when measuring a single point temperature that is within 50°C of ambient.
If the temperatures are excessively high or low, a thermistor will not work.
Most thermistors work best in the range between -55°C and +114°C.
Sensitivity of thermistor is high.
Span value of thermistor is low.