Electrical Machines Minimum allowable resistivity of power transformer insulating oil is generally taken as 2 X 1012 Ω - cm at 27°C and 0.2 X 1012 3 X 1012 Ω - cm at 27°C and 0.3 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 2 X 1012 Ω - cm at 27°C and 0.2 X 1012 3 X 1012 Ω - cm at 27°C and 0.3 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 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A DC motor with armature resistance of 0.5 ohms connected directly to a 220 Volt supply. If the armature is stationary then the current flowing through the armature is 340 A. 440 A. 570 A. 250 A. 340 A. 440 A. 570 A. 250 A. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Consider the following statements : Interpoles in dc machines 1. reducearmature reaction effects in the interpolar region 2. have the same dimension as main polls 3. have their windings connected in series with the armature 4. have same number of turns as the armature 5. have the polarity same as that of the main pole ahead in a motor From these, the correct statements are 1, 2 and 3 1, 3 and 5 1 and 3 1, 2, 3 and 5 1, 2 and 3 1, 3 and 5 1 and 3 1, 2, 3 and 5 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If the field circuit of a DC shunt motor is opened The speed of motor will be reduced. DC Shunt Motor The motor will attain dangerously high speed. The armature current will reduce. The speed of motor will be reduced. DC Shunt Motor The motor will attain dangerously high speed. The armature current will reduce. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The commutator segments of DC machines are made up of copper alloy copper hard-drawn copper brass copper alloy copper hard-drawn copper brass ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines which of the following type of brush and their application is/are correct electro graphite → large ratings All of these copper graphite → low voltage high current density carbon brush → normal ratings electro graphite → large ratings All of these copper graphite → low voltage high current density carbon brush → normal ratings ANSWER DOWNLOAD EXAMIANS APP
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