Voltage Analyzers

Hi Almio,

What kind of turbines are you working with?

Rgds.

Ani-Luo

We work whit "Solar turbines", but I need to know the characteristics of a electric analizer, for voltaje, current, etc.

Regards

for phase, noise, harmonics, etc., a good multiple trace oscilloscope is hard to beat. To use it for current, you'll need one or more shunts. And of course some knowledge of how to connect it and what to look for. Make sure input ground is isolated from power ground!

If he doesn't know much about voltage analyzer, he will not get any useful info out of an oscilloscope. He might even destroy it if he doesn't have the right probes.

He needs a power meters which will indicate what the current and voltages are doing without having to calculate it from the waveform. I use a Hioki which is "relatively" simple for three phases measurements. There are many other similar equipments that can be rented for a month or two. He needs to know the voltage and current to select the probes. He will be able to trigger on frequency, voltage, or current variations, measure harmonics etc... These tools are made for this kind of work and are relatively safe to use.

This will require some learning of the basic concepts though.

You are probably right...

On the other hand, Almio is in Peru; it may not be possible to rent such devices there. What does it cost to purchase one?

This is really out of my areas of expertise...

Between $7000 to $15 000 depending on the make and specific model. It is about the same as an oscilloscope with the probes and you can get at least six channels of recording. He could probably find a two channel meter for about $3000. There are other cheaper meters that can do some of the work but they are not safe for professional work on many hundreds of volts.

It all depends on what he is trying to do and his budget.

If Almino's company pays for the trip, I could bring mine there for a few days and show him how it works. I could visit the country side while he takes his measurements... There are lots of nice things to see there.

I think you more need a fast fourrier transform .... to see the harmonics

Are you referring to an instrument, or a mathematical procedure?

Tektronix makes a scope for just this purpose. It does multi-phase voltage, power factor, current, Harmonics, etc.

http://www.tek.com/products/oscilloscopes/tps2000/

Those make marcot's devices sound awfully expensive. I didn't look closely enough to see whether they have digital readout of phase etc, but since my 20-year-old Tektronix has digital readout of several values, I would expect them to.

I think it should be obvious that any instrument measuring such values is going to require some training of the operator, who should already have considerable technical education before this training.

It all depends on what you are trying to achieve. This is similar to a multimeter. You can get one at Wall mart for $10 or buy a Fluke for $500. They both read voltage and current but you get what you pay for.

When you have a professional application, you must spend the money to be safe and record all the info needed.

Almio probably needs to record production over long period of time and generate graphs. He needs a power survey instrument, not an oscilloscope that is made to give snapshots when one triggering conditions is encountered. A good power meter can have dozens of triggering thresholds on various parameters and also record snapshots at variable time interval. All this data is usually stored on a memory card that can be analysed on a computer for reporting purpose.

P.S. I like the fluke portable power meter for simple troubleshooting but it is not suitable for the type of power system studies that I do. The Tektronix suggested above is not suitable for three phase power measurement. It is a laboratory tool for electronics application. You could use it but it is like using a stone instead of a hammer to drive a nail in.

You need the mathematical Fourrier principle to calculate the higher harmonics out of the voltage variations in respect to time.

According to the Fourrier calculation, you can "switch" form time dependent signals to frequecy dependent signals.

This calculation is done in a spectrum analyser or a FFT analyser.

If you put an in time variating voltage signal through a FFT analyser, you get the fundamental frequency and the higher harmonics. Each harmonic has an amplitude value and a shift angle acording to the fundamental.

This is a basic function found on every power meter and some oscilloscope. It has been a standard feature of power meters for at least 20 years.

Look at the Yokogawa series, WT1600 or PZ4000. Expensive but accurate and will measure the harmonics with the built in scope.