What is the relation between magnetising current and power factor?
What is the relation between the magnetizing current and power factor? Explanation: Magnetizing current is indirectly proportional to the power factor. As the magnetizing current is large, the power factor is poor.
What is magnetising current?
Magnetization current can be defined as “the portion of the no-load current that is used to establish flux in the core of a transformer“. It is generally denoted by the letter Im. Generally, when a transformer is energized under no-load conditions, it draws a small amount of current.
What is effect of magnetizing current on power factor of transformer?
The results show that the magnetization current and harmonic content increase significantly when high magnetic flux densities are injected and vice versa with power factor that decrease sharply. These phenomena can be used as the indication of transformer core saturation.
What is magnetising current in current transformer?
The current that flows through the primary winding of a power transformer when no loads are connected to the secondary winding; this current establishes the magnetic field in the core and furnishes energy for the no-load power losses in the core. Also known as exciting current.
How is magnetising current calculated?
This is the magnetizing current ( no secondary current ) and is governed by the differential equation V(t) = L x d(I)/dt + Rp x I(t), with units of volts, henries, amps, and seconds.
What is magnetising current in induction motor?
In order to set up magnetic flux inside the air gap of induction motor, large magnetizing current is required. During no load, the current drawn by induction motor is 30%-60% of rated current whereas current drawn by transformer during no load is 2%-6%.
How can magnetising current be reduced?
It is revealed that the primary winding of the transformer with concentric windings is optimally arranged further away from the magnetic circuit. This will allow to reduce the magnetizing current when working under load and to reduce iron losses.
Why transformer has harmonic in the current?
When transformer is energized the magnetizing current drawn by it is non linear and it generates harmonics. This is because, when transformer is energized the back emf is zero and transformer draws huge magnetizing current which is not sinusoidal. The magnetizing current is rich in the 2nd order harmonic current.
What is function of magnetizing and working current in transformer?
Active or power component (Iw): It is also known as a working component. It is in phase with the applied voltage V1. It supplies the iron losses and a small amount of primary copper loss. The function of the magnetizing component is to produce the magnetizing flux, and thus, it will be in phase with the flux.
What is magnetizing current test?
Magnetizing Current test on transformer is performed to locate defects in the magnetic core structure, shifting of windings, failure in between turn insulation or problem in tap changers.
Why magnetising current in an induction is higher as compared to a transformer?
The magnetic circuit of the induction motor has an air gap and hence higher reluctance as compared to a transformer magnetic circuit having no air gap. In order to set up magnetic flux inside the air gap of induction motor, large magnetizing current is required.
How do you calculate magnetising current?
Why do we test magnetizing current in transformer?
What happens if harmonics occur in a transformer?
Transformers:Harmonics in transformers cause an increase in the iron and copper losses. Voltage distortion increase losses due to hysteresis and eddy currents and causes overstressing of the insulation material used. The primary effect of power line harmonics in transformer is, thus the additional heat generated.
How do harmonics affect power factor?
The distortion power factor term is introduced by the harmonics. A closer look at the signal will show that the current waveform is no longer a 60-hertz sine wave. The harmonics introduce high-frequency content that converts it into a double-hump pattern (see figure 2).
How can harmonics be reduced?
Adding a line reactor or transformer in series will significantly reduce harmonics, as well as provide transient protection benefits. Transformer connections can be employed to reduce harmonic currents in three-phase systems.
What is THD power quality?
Total harmonic distortion, or THD, is one way to gauge power supply quality. It indicates how much of a harmonic component the voltage and current waveforms contain, and it serves as an indicator of the extent of the waveform distortion that is caused as a result.
What is the total harmonic distortion of a magnetizing current?
The magnetizing current (Io) and harmonics phenomena which are evaluated in terms of percent total harmonic distortion of current (THDi) and power factor are shown in Table 1. The excitation (magnetiz ing) current, Io at magnetic flux density B = 1.8 T (i.e., Io = 0.827 A) is more than doubled compare to at 1.4 or 1.5 T (Io = 0.317 A or 0.388).
How to estimate the harmonic estimation of magnetization currents?
An analytical method for harmonic estimation of magnetization currents has been developed. The method is based on the results of the waveforms qualitative analysis. The calculation and the experimental results are compared. A good matching is observed.
What are the characteristics of magnetizing current?
The magnetizing current is, however, symmetrical. The result of resolving this waveform into a series of component sine curves, is a curve of a fundamental frequency and a series of odd harmonics, with the third harmonic prevailing. The exciting current is obtained, in a similar way, considering the hysteresis losses.
How to manage harmonics in power system?
Managing harmonics in power system is joint responsibility of both customer and utility; therefore harmonics limits are recommended for both voltages and currents. As discussed in Section 1.3.4, voltage distortion can be kept below objectionable levels by limiting harmonic current injection by consumer or user.