Wiki
Home » Blog » Wiki » Negative sequence

# Negative sequence

Negative sequence will not cause a physical rotation. This component creates a field which, though not strong enough, tries to counter the primary field, An increase in this component will cause the motor to overheat due to the opposition. a physical rotation is not likely to occur.

Negative sequence currents are produced because of the unbalanced currents in the power system. Flow of negative sequence currents in electrical machines (generators and motors) are undesirable as these currents generates high temperatures in very short time. The negative sequence component has a phase sequence opposite to that of the motor and represents the amount of unbalance in the feeder. Unbalanced currents will generate negative sequence components which in turn produces a reverse rotating filed (opposite to the synchronous rotating filed normally induces emf in to the rotor windings) in the air gap between the stator and rotor of the machines. This reverse rotating magnetic field rotates at synchronous speeds but in opposite direction to the rotor of the machine. This component does not produce useful power, however by being present it contributes to the losses and causes temperature rise. This heating effect in turn results in the loss of mechanical integrity or insulation failures in electrical machines within seconds. Therefore it is undeniable to operate the machine during unbalanced condition when negative sequence currents flows in the rotor and motor to be protected. Phase reversal will make the motor run in the opposite direction and can be very dangerous, resulting in severe damage to gear boxes and hazard to operating personnel.

Calculate (3 - 1) =

You may also like:

As a mathematical tool eventually, simulation can help to quickly approach the results that we need. If everything is done in right way, simulation can give us reliable conductive EMI results at the low ...
A frequency inverter controls AC motor speed. The frequency inverter converts the fixed supply frequency (60 Hz) to a variable-frequency, variable-voltage output to enable precise motor speed control. Many ...
Before you attempt to dissipate causative factors of harmonics verbally, you take a look at several studies done by NEMA regarding such, and look into variable frequency drive (VFD) a bit better. You can view ...
DC drive technology is the oldest form of electrical speed control. The speed of a DC motor is the simplest to control, & it can be varied over a very wide range. These drives are designed to handle ...
Transistor frequency inverter has the following disadvantages: easy trip, difficult re-start, poor overload capacity. As the rapid development of IGBT and CPU, the inverter drive integrates perfect ...
Gozuk Blog: all about electric motor control & drives industries development in energy saving applications.

Featured

Like pumps, fans consume significant electrical energy while serving several applications. In many plants, the VFDs (variable ... A frequency inverter controls AC motor speed. The frequency inverter converts the fixed supply frequency (60 Hz) to a ... Motor starter (also known as soft starter, motor soft starter) is a electronic device integrates soft start, soft stop, ... Soft starter allows the output voltage decreases gradually to achieve soft stop, in order to protect the equipment. Such as the ... Soft Starter reduces electric motor starting current to 2-4 times during motor start up, reduces the impact to power grid during ...

In Discussion