This document discusses electrical vibration, its causes, and problems it can create. It defines vibration as oscillation around an equilibrium point, and electrical vibration as occurring in electrical devices due to forces from charged particles. Electrical vibration can be caused by issues like a broken rotor bar, current variations from rotor-stator faults, air gap dissymmetry between stator and rotor, stator eccentricity, and induced current in rotor bars under load. These issues can create vibrations at different frequencies like slip frequency, 2x slip frequency, and 2x line frequency, indicating different rotor or stator problems.

1. Vibration of Electrical Problem

2. Levina Ariesta Mayasari
R. Hasta Wiratna
Yohanes Suharsoyo
Dhiaurochman Airlangga
14/366956/TK/42256
14/363308/TK/41452
14/366942/TK/42253
14/363294/TK/41446

3. What is Vibration ?
Vibration is a phenomenon whereby
oscillators occur about an equilibrium
point. The word comes from Latin
vibrationem ("shaking, brandishing").
The oscillations may be periodic, such
as the motion of a pendulum—or
random, such as the movement of a
tire on a gravel road.

4. What is Electrical Vibration ?
On electrical sector, vibration often found in many
devices, such as electric motors, power
transformers, electrical inductors and even in
batteries.
A vibration that caused by an amount of force that
applied to a particle. Suppose that we have a
metal. At a normal state, there is no direct
electrostatic force acting on the metal because the
metal’s total electric charge is basically zero.
However if the metal gets charged locally by the
electricity. The electric field polarizes the metal. It
means that one side of the metals (measured
relatively to the direction of the source of the
electrostatic field) is positively charged while the
opposite side is negatively charged.
How an electric-conducted things could even vibrate?

5. The total force acting on this polarized object would be zero if
the electrostatic field were uniform and constant in time. But
when the electric field is non-uniform (which may also be
guaranteed by its being time-dependent because the signals only
propagate by the speed of light), there will be a net force acting
on the keys.
So one side of the metal get the charge Q+ while the opposite
side would be charge Q-. If the electric field oscillates, the
electric field may be higher on one side than on the other, so
there will be a net force. The electric field may fluctuate. When
the object is light enough relatively to the force caused by
electric field, the metal will move or oscillate.
Electrical vibrations can be caused by slip of frequency due
to several reasons. The slip of frequency caused unbalanced
torque motor which make the vibration exist.
How an electric-conducted things could
even vibrate?

6. Problem of Electrical Vibrations
1. Broken Rotor
If a rotor bar is broken in this bar will be no current
and no magnetically field. The magnetic unbalance occurs
between the two opposite side of the motor, side with the
broken bar and side with the unbroken bar. The unbalance
creates a magnetic force which rotates with rotational speed
and modulates at the frequency equal to the slip frequency
times the number of poles. Likewise if one of the rotor bars
has a different characteristics.

7. 2x Slip Frequency

8. 2. Current Variations Due to Rotor Stator Faults
Problem of Electrical Vibrations
The induced current creates around the bars a
magnetic field and this generates an attracting force with
radial and tangential components to the stator teeth and
vibration will appears. This high frequency vibrations are
related to electrical noise and are the principal noise
source. The amplitude of this vibration depends on the
load.

9.  1x, 2x, 3x, RPM with pole pass frequency sidebands
indicates rotor bar problems
 2x line frequency sidebands on rotor bar pass frequency
(RBPF) indicates loose rotor bars
 Often high level at 2x and 3x rotor bar pass frequency and
only low level at 1x rotor bar pass frequency

10. 3. Air Gap Dissymmetry Between The Stator And Rotor
It will appear a non-symmetrical magnetic pull force
which is proportional with the square of magnetic
induction and inverse proportional with the air gap
distance. The rotor is pulled in one direction and the stator
is pulled in opposite direction and this influences the right
functioning of the bearing. The force is maximum where
the air gap is minimum.

13. 4. Stator Eccentricity, Shorted Laminations and Loose Iron
 Stator problem generate high amplitudes at 2FL (2x line
frequency)
 Stator eccentricity produces uneven stationary air gap,
vibration is very directional
 Soft foot can produce an eccentric stator

14. The induced current creates around the bars a magnetic
field and this generates an attracting force with radial and
tangential components to the stator teeth and vibration will
appears. This high frequency vibrations are related to electrical
noise and are the principal noise source. The amplitude of this
vibration depends on the load.
5. Current Induced Into The Rotor Bars Under load

15. The induced current creates around the bars a magnetic
field and this generates an attracting force with radial and
tangential components to the stator teeth and vibration will
appears. This high frequency vibrations are related to electrical
noise and are the principal noise source. The amplitude of this
vibration depends on the load.
5. Current Induced Into The Rotor Bars Under load

16.  Phasing problems can cause excessive vibration at 2FL with
1/3 FL sidebands
 Level at 2FL can exceed 25 mm/sec if left uncorrected
 Paaarticular problem if the defective connector is only
occasionally making contact

17. Loose stator coils in synchronous motor generate high
amplitude at Coil Pass Frequency
The Coils Pass Frequency will be surrounded by 1xRPM
sidebands
6. Synchronous Motor (loose Stator Coils)

19. Daftar Pustaka
Glenn H.Bate, “Vibration Diagnostics for Industrial Electric Motor Dives”. Bruel & Kjaer. BO-0269
Dương Phuc. 2015. “Basic of Vibrations”. Slideshare, PVGAS.
Agoston, Katalin. 2014. “Fault Detection of The Electrical Motors Based on Vibration Analysis”. 8th
International Conference Interdisclipinary in Engineering. 9 – 10 October 2014. Romania

20. Thank You