MGVCL Exam Paper (30-07-2021 Shift 1)
Determine maximum permissible load which a 15 MVA, ONAN cooled transformer to IS : 2026 can take for 6 hr, if the initial load on it was 12 MVA. The weighted ambient temperature is 20˚C. Assume the permissible load kVA as a fraction of rated kVA is 1.25.
Power factor for purely inductive circuit is 0 and power factor angle is 90 degree. Power factor for purely capacitive circuit is 0 and power factor angle is 90 degree Power factor for purely resistive circuit is 1 and power factor angle is 0 degree
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.
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
Symmetrical breaking current: It is the rms value of a a.c component of the current in the pole at the instant of contact separation.
Asymmetrical breaking current: It is the rms value of the total current comprising the a.c and d.c components of the current in the pole at the instant of contact separation.
EXAMIANS