Power line harmonics

'Useful' power is power getting to the desired load to do the desired work. I think the higher frequencies are less efficient at delivering power. Hysteresis causes heat in metal- this effect increases with frequency. So, harmonics take power from the input but do not deliver it well to the desired output.

Stick around though, because I am sure a more correct answer will be coming.

Hi Mevel,

The necessity of usage of different frequency is different. For example In Induction heating different frequencies are used for different purpose. 2- 8 K Hz is used for Heavy engine components like crank shaft hardening .As penetration of heat and hardness is required for little more depth from surface. Where smaller components like rocker arms pins etc needing only surface heating and hardening ,HF to the tune of 450 K Hz is required . The more the frequency the more skin effect. Higher the Frequency the current will pass through the outer surface only. similarly To get higher speed for induction Motors Higher frequencies are used. So The frequency is selected as per the requirement of the job. When we design a motor to work on a specific frequency like 50 Hz or 60 Hz the torque and speed of the motor will depend on frequency N= 120 x f / P .So If First or second Harmonics are prominent what can be the effect on the speed and Torque of the Motor. So It is essential that harmonics are to be suppressed to get clean power supply.So I agree with your view. Harmonic suppression is a good subject for discussion for Engineers .so more views should come from experienced Engineers.

Just an engineering note. The first harmonic that you have mentioned is the fundamental frequency. Think about it?

Harmonics are whole integer multiples of the fundamental frequency. When I went to school, a value times ONE was unchanged, course that's a loooong time ago.

And the next commenter is correct. resistive loads will respond to harmonic voltages with relation to the RMS value of the waveform.

Dear Snakers My reply was not a reply to the original question of Harmonics but a clarification to the reply 1 of mevl 123 where in I felt he was getting confused with the issue of Harmonics with other primary higher frequencies .So my reply was meant to him to explain that position .As regards the effect of harmonics in regular power system is different matter and if I remember it was well discussed in one of the previous questions. So I did not wanted to discuss further to the original question of Harmonics and only made a passing comment. It will be nice if you also read earlier discussions on the subject and give your detailed views. Your views on original question is very much valued and your views should come forward. Thanks and good day.

I think it is possible...if you have only all resistive loads.

As mentioned by others, resistive loads respond to the harmonics just fine. This includes heaters [wanted responses] and loss components [unwanted responses]

Machines (motors etc.) use the relationship between the position of the coils and the phase of the supply to generate the motive force. Depending on the various relationships, overtone harmonics can assist or detract from the drive force - but even when they help, they are likely to be more lossy than the frequencies for which the motors were designed.

Dear Sir,

i am student of the electronics and working in the field of Induction heating equipment. we manufacture TRIODE VALVE based, IGBT based and SCR based Induction heating equipment for many more application for heating of metals.

we are using 3phase 4 wire 440V AC 50Hz as a input to the machine. And i am working on the series inverter where outpur frequency of 8KHZ to 40 KHZ range.

as i am not aware of the basics and design part very well, so help me.

i need to measure the following:

1. Input power calculation
2. input hormonics calculation
3. Outout power calculation.
4. Impedance matching transformer design.
5. Resonance Lead-lagging.
6. tank capacitor calculations.
7. i want know more about IGBT protection devices, coz i am having problems with IGBT's.

NOTES:

1. Using PWM IC 3825 for basic frequency generator.
2. I am using semikrons IGBT modules like SKM100GB128D and IGBT driver SKHI22A.
3. For AC to DC: 3 phase rectifier module.
4. for transformer: U shape ferrite core, litz wire as a primary and copper tube as secondary.

plz give some time to answer my question. i am very much needy for this as u r the masters.