I agree to the terms of the site Privacy Policy

Total Harmonic Distortion (THD)


Dear readers,

Triol Corporation operates all over the world and each region has special requirements to the system.
Today we will have a talk about total harmonic distortion (THD).
I chose 2 most oil-rich parts of the world: Middle East and USA to be considered in the blog.
THD level influences the elements of power supply systems and communication lines. The main forms of influence of higher harmonics on the power system are:
– increasing in currents and voltages of higher harmonics due to the parallel and serial resonances;
– decreasing of the generation process efficiency, transmission, electricity use;
– aging of electrical equipment insulation and reduction as a consequence of its service life;
– false equipment operation.
Reasons for the emergence of higher harmonics are plugged tools, that having non-linear input circuit and thus consuming impulse current. The nonlinear character of the circuit is determined by non-linear semiconductor elements (rectifier bridges, diodes, thyristors, etc.). Each VSD is composed of such types of items.

Let’s talk about regions where THD level is one of most main and indispensable requirements.

Middle East – one of the biggest parts of the oil world. Almost all oil wells located in a desert, place where to put cable line is very hard and either expensive. That’s why for supply VSD’s in the fields, service companies mostly use diesel generators. The nonlinear distortion introduced by the load primarily affects the performance of a diesel generator. The THD influences on the parameters of the diesel generator: the larger its value, the higher the power of the diesel generator. More kilowatts means more generator price. Moreover, high THD level has affect on generator reliability and durability – it is significantly reduces them. Simple wells without production are very, very expensive. I would rather say extremely. That’s why very often there can be found systems with various filters and systems with other technical solutions to reduce the level of nonlinear distortions.

USA – the highly developed country with fuel-and-power resources. Requirements to THD are not that exact as at Middle East but, that is more about economical effect. Compared to the East, in America, the oil flow is much smaller and cost of production is much more expensive (taxes, electricity price, salaries, etc.). As we know from previous topic, high distortion level entails large power losses, accordingly, electricity and a large percentage of failure of equipment that means increasing of the maintenance and repair costs. That’s why complete system with THD filter gets more economical effect on oil production. Another feature of the American oil market is that VSD’s are connected to the same power line as transmit devices. Harmonics in power circuits cause noises due circuits. Low noise level leads to discomfort, when the increase of the transmitted information is lost, in extreme cases, the communication becomes impossible.

There are many various methods of dealing with harmonics, such as: using of 12 and 24 pulse rectifier scheme, active’s and passive’s filters, but it is another theme to discuss 😉

North and Latin America…


Dear Readers! Triol cooperates with global industrial market for 25 years and surely knows what…

Variable Speed Drive for…


Hello dear Readers! It’s been a while since my last blog. Sure, you remember my…

Let me invite you…


Hello, dear readers! It’s been a while since my last blog. And today I’ve got…

CE marking for Surface…


Dear Readers! As you probably know, our company has received the CE certificate for Surface…

My trip to Argentina…


Hello Dear Readers! Today I’ll tell you about my trip to Argentina and Venezuela. It…

General comments:

Leave a Reply

Comments from Facebook: