What causes motor unbalance?

Increased temperature reduces motor or equipment life leading to premature failure. A phase unbalance may be caused by unstable utility supply, unbalanced transformer bank, unevenly distributed single-phase loads on the same power system, or unidentified single-phase to ground faults.

What can cause unbalanced phase voltages to a motor?

Unbalanced voltages usually occur because of variations in the load. When the load on one or more of the phases is different than the other(s), unbalanced voltages will appear. This can be due to different impedances, or type and value of loading on each phase.

What happens if the induction motor runs on unbalanced voltage?

When line voltages applied to a polyphase induction motor are not exactly the same, unbalanced currents will flow in the stator winding, the magnitude depending upon the amount of unbalance. The effect on the motor can be severe and the motor may overheat to the point of burnout.

How do you fix unbalanced voltage?

Redistributing and reconnecting single-phase loads can reduce voltage unbalance caused by excessively unequal load distribution among phases. The most prevalent culprits among heavy, single-phase loads are lighting equipment and occasionally welders.

What is unbalanced power?

What is unbalance? Definition. A three-phase power system is called balanced or symmetrical if the three-phase voltages and currents have the same amplitude and are phase shifted by 120° with respect to each other. If either or both of these conditions are not met, the system is called unbalanced or asymmetrical.

What is an unbalanced motor?

Unbalanced motors are three-phase, asynchronous motors with centrifugal weights, which are attached to the ends of the motor shafts. The size of the unbalance, and with it the amplitude of the oscillation by the working unit, can be adjusted by shifting the centrifugal weights when the motor is not in operation.

What problems can an unbalanced supply voltage create?

The main effect of voltage unbalance is motor damage from excessive heat. Voltage unbalance can create a current unbalance 6 to 10 times the magnitude of voltage unbalance. In turn, current unbalance produces heat in the motor windings that degrades motor insulation causing cumulative and permanent damage to the motor.

Why is an induction motor very sensitive to unbalance in supply voltage?

Large induction motor is very sensitive to unbalance in supply voltage. The negative sequence component, which comes into picture because of the unbalance in the supply, is particularly troublesome. This is because the motor offers very small impedance to the negative sequence currents.

What is voltage unbalance factor?

According to IEC 60034-26, Voltage Unbalance Factor (VUF or Kv) (Quispe et al. 2005; Adekitan and AbdulKareem 2019) is the ratio of the negative-sequence voltage (V2) to the positive-sequence voltage (V1). Also, this definition ignores the phase angle.