Improper Brush -

Commutator Contact

(D.C. Motors)

Radial, Transverse

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n = any positive integer

C = Number of commutator

segments.

X = machine speed (RPM)

Broken Rotor Bars

2 x Slip x No. of Poles

Radial, Transverse

Sometimes Beating

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Sometimes causes 2 x Slip sidebands around 120 Hz

Induction Motor Slot

Pass

Radial, Transverse

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S = rotor slot pass frequency, Hz

B = number of rotor bars

X = rotor speed (RPM)

120 = twice line frequency , Hz