Electrical Machines Minimum allowable resistivity of power transformer insulating oil is generally taken as 4 X 1012 Ω - cm at 27°C and 0.4 X 1012 3 X 1012 Ω - cm at 27°C and 0.3 X 1012 2 X 1012 Ω - cm at 27°C and 0.2 X 1012 1 X 1012 Ω - cm at 27°C and 0.1 X 1012 4 X 1012 Ω - cm at 27°C and 0.4 X 1012 3 X 1012 Ω - cm at 27°C and 0.3 X 1012 2 X 1012 Ω - cm at 27°C and 0.2 X 1012 1 X 1012 Ω - cm at 27°C and 0.1 X 1012 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines For a DC Shunt Motor having armature resistance of 0.5 Ω and 2A armature current at no-load, when the armature current is changed to 20A at loaded condition the speed is 1000 r.p.m. What is the speed at no-load? 1130 r.p.m. 1037.5 r.p.m. 4575.4 r.p.m. 963.8 r.p.m. 1130 r.p.m. 1037.5 r.p.m. 4575.4 r.p.m. 963.8 r.p.m. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a dc machine 4 pole lap winding is used. The number of parallel paths are? 8 4 1 2 8 4 1 2 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Under which of the following conditions is a dc motor provided with compensating winding used ? 1. Wide range of speed control above normal 2. Wide range of steady load variation with no speed control 3.Wide range of rapid variation in load Select the correct answer using the codes given below : Codes : 1, 2 and 3 2 and 3 1 and 3 1 and 2 1, 2 and 3 2 and 3 1 and 3 1 and 2 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A series generator is connected in series to a feeder having 0.5Ω resistance to boost the voltage. The induced voltage is given by Eg = 0.6Ia, Ra = 0.2Ω and Rs = 0.3Ω. Find the voltage boosted by the generator, when delivering 400 Amp? 30 V. 40 V. 90 V. 60 V. 30 V. 40 V. 90 V. 60 V. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In case the conditions for maximum power for DC motor are established, the efficiency of the motor will be Any where between 75 % and 90 %. Around 90 % Around 100 %. Less than 50 % Any where between 75 % and 90 %. Around 90 % Around 100 %. Less than 50 % ANSWER DOWNLOAD EXAMIANS APP
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