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Sorry for bumping this to the top. Can anyone help?

Hi all, on completing a harmonics study on the LV side of a newly installed plant we now what to work out what harmonics levels are present on the HV side (both current, voltage and THD). the customer has their own transformer so they are only interested in what harmonics are present on the HV...

Thanks guys...

Hi, a few general questions on source impedance: 1. Why is mains a low source impedance? 2. Why are generators a high source of impedance? 3. and how does this high source impedance result in higher voltage waveform distortion where harmonics are concerned? Thanks for your help in advance...

We have a flowmeter that has the transducer on the end of the probe and is therefore installed at the application point on the air vent pipe. these pipes are at high level and not easily accessible which is a problem for servicing and calibration. does anyone on here know of an instrument...

Think you've typed it in wrong. If its 26kA for 1 sec then its a short circuit capacity of 26000 amperes rms symmetrical available at incoming line terminals of the MCC.

It looks like solidworks is more mechanical based and Altium more electronic? We'd be looking at mains distribution, motor starter drawings, instrument & control and panel layout. Thanks for all the info to date. how long does it take to set the drawing template and the parts catalogue for...

Thanks Marke, I'll try and get a look at your site (and software) over the holiday. John

Just out of interest Marke, how do you size your fans for a PFC unit. Are there ref tables? Is it acceptable to power the fans off the contactors, or better to use the thermostatic control? Thanks for your help.

Thanks Marke, we're looking into that at the moment.

got it sorted (we think) and thanks for all your help. We had one 4sqmm cable coming from our main fuseswitch and daisy chained to each of the four contactors! We changed it for a 16sqmm from the main fuseswitch down to a distribution block and then fed each of the contactors seperately with...

So does that mean the filtering unit needs re-commissioned or that we have the wrong type/size of reactors and/or capacitors in the PFC unit? Thanks for your help. It's off at present, and we're heading to the site early next week so we'll check the voltages then.

We installed a PFC unit at one of our sites as well as an active filtering unit. Now because our capacitors were not de-tuned, the PFC unit would not operate as required (or so we were told). We have now installed series inductors to detune the unit, however the cables coming from the...

Thanks guys. We've been looking at both the promis.e and autocad electrical packages. I'd be very interested to hear about your querks djs. I think promis.e might be more favoured as it has also speeds up the panel design process. Did you have any dealings with that end of the package?

Folks, Our company is looking into getting a more intelligent electrical design software package than the one we are using. We’re trying to reduce the human error factors! Say we had to add an extra wire or relay to our motor control drawing, we might forget to number it, or have multiple...

Evening all. The new G5/4 regulation requires new (and possibly existing?) plant to comply within harmonic limits. At the design stage, you are required to forecast the harmonic levels the plant will generate. Now there seem to be a couple of companies offering to do this for you (at a tidy...

I’ve a few questions here! Do the new G5/4 requirements apply to generators? Different companies can perform calculations to inform you what size and type of filter you require for your plant to be G5/4 compliant but sometimes these calculations do not take into account the situation when the...

There is a harmonic measurement device on the harmonic filters. Not actually sure of the readings, but they cannot go higher than the limits outlined in G5/4. We just assumed if the harmonics were kept low with the filters then the PFC caps would be ok, but now not so. We did do calculations...

Evening all, I’ve a query regarding the use/need for de-tuned capacitors. Plant majority is VSD and there is an active harmonic filtering section to comply with G5/4. Now because we have the harmonic filter, we need de-tuned capacitors in our PFC section. I know it’s something to do with...

Anyone any ideas?