MGVCL Exam Paper (30-07-2021 Shift 1)
Case 1: The PV connected to the DC bus was injecting 20 kW of power constituting of 1 kW of loss Case 2: The same PV is connected to the AC bus constituting to 1.5 kW loss. Find out the change in efficiency from Case 1 to Case 2?
In DC microgrid system, Efficiency α 1/Pin For 1 kW loss injecting power is 20 kW For 1.5 kW loss injecting power will be proportional to 30 kW So, Efficiency will be reduced 0.025
The electrostatic stress in a cable is not uniformly distributed. The potential gradient is inversely proportional to the distance from the centre of the cable. Hence, it will be maximum (gmax) at the surface of the conductor and goes on decreasing until it becomes minimum (gmin) at the surface of the sheath. That means electrostatic stress in the dielectric of a cable is maximum at the surface of the conductor and minimum at the surface of the sheath.
Voltage sag: 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
Intern turn winding fault can be easily detect by differential protection relay. Also detect by buchholz relay (gas operated relay), cause buchholz relay is used to detect the internal fault of transformer.
As per the key statistics data of IEA With electricity consumption reached to 1,164 TWh in the country till November 2019, India ranked third among the top ten electricity consuming countries across the globe.
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