Recent content by F.ono

I am working in a project that contain several switchboards that will receive an optical fiber from encoders of the motors that they feed (through an optical transmitter). It appears that to do this we will need Mini-DIOs to connect this fiber cord to optical receivers, which in turn will be...

I have been an electrical design engineer for 3 years now and although I like what I do, sometimes I feel like there's something lacking about the job. I mean that I hardly get my hands dirty by actually assemblying or giving maintenance to the equipment that I design. I know that there are...

I work as a project engineer of electrical equipment for substations. More and more I have to deal with the communication of these equipment with PLC and other equipments. But I really don't know much about this area. For example, we have Modbus, Profibus, IEC-61850... every now and then I have...

Thank you all for your answers! I'll read them carefully and I'll ask again if I need more help!

Answers in red!

As surprising as it seems, many things are done in projects without anyone knowing why they're done.

I recently started working at ABB as a engineer. I wish someone here could help with some questions: 1) In a single phase IT system, why does the circuit breakers have to be bipolar? I believe it is because of a second fault occurence, but i don't really understand what happens. 2) If you...

I've been reading about earthing of electrical systems. The book that I'm reading states that transient overvoltage occurs mainly on no earthed systems, but it doesn't explain why. Could someone enlighten me? It also says that overvoltage can degrade equipments, damage electronic components...

Another question: What is the fundamental frequency of the pulse? Do I just have to consider the total time that it took from start to end and calculate 1/T?

In order to understand why the rogowski coil is not working as a self-integrating coil (as it is supposed to in high frequencies), I found the article attached. Section D in that article explains the self-integrating behavior. But it is necessary to understand Equation (1), which I am not really...

Thank you for your answers! It really helped me understanding what is going on. For high frequencies, the rogowski coil is supposed to be self-integrating, that is why I didn't even think that what I was getting was the di/dt wave. But this self-integration characteristic depends on the 2pifL...

I've been doing some test on a rogowski coil that I built. It is like an air-cored current transformer. I am using it to measure high frequency pulses. The picture shows a discharging capacitor being captured by a current probe (above) and by the rogowski coil (below). I don't know what is...

Thank you all and sorry for taking so long to reply. I used a metal layer resistor and it worked much better.

Thanks berkeman! Does this internal impedance varies with frequency? I am asking this because i was getting voltage outputs between 0,8~1,3 V depending on the frequency. Oh, another thing... the resistor is a wirewound type. For that range of frequency, is the reactance considerably large...

I was using a signal generator to perform some tests. The circuit was simply the generator in series with a 1 ohm shunt resistor. Even though I was working with high frequencies (1 to 20 MHz), shouldn't the voltage drop across the resistor be the generator amplitude itself? I was using the...