For 6252 AT/Poles, if brush shift is of 2.50 mech

for-6252-at-poles-if-brush-shift-is-of-2-50-mech-degrees-what

For 6252 AT/Poles, if brush shift is of 2.50 mech. Degrees, what will be the demagnetizing ampere-turns per pole for a 6-pole DC machine?
A. 521
B. 5731
C. 5231
D. 571
Right choice is A. 521

From given mech. Degrees shift we need to find electrical degrees shift. Electrical shift= mechanical shift*(P/2). Thus, electrical shift is equal to 7.50. Demagnetizing ampere-turns is given by 6250*(2*7.5/180) = 521 AT/Pole.