Recent content by sky2020

Any good books in Relay Coordination Studies preferably with ETAP?

How to define Meter demand hourly usage in CYME? I have the hourly total metering upstream the feeder and not sure how can I put the data as a time-series for a meter.

The utility provided the three phase fault with X/R and the 1-ph fault with X0/R0. How do I map these values in the ETAP model? Which value should be compared to ETAP reports? Is that the 3-Phase Fault 0.5cyc kA Symm. rms? I mean it should not be the Asymm. kA or the 4cyc or the minimum fault...

The reference is IEEE Std 242 & C37.91

I have questions about primary and secondary transformer protection. Primary transformer protection is protecting the mechanical and damage curve of the transformer. It should not respond to secondary transformer faults. It should allow inrush current. Primary transformer protection does not...

I was checking the actual Ig value and CTR was the correct value to multiply with the IG to get the actual Ig current. CTRN and CTRG were wrong values. Can I multiply IG * CTR to get the actual Ig? PHASE CT RATIO 1–5000 CTR := 400 NEUTRAL CT RATIO 1–5000 CTRN := 120 IG SOURCE MEAS, CALC IG_SRC...

Should the transformer differential protection (87) be responsible on detecting single phase to ground faults inside the transformer? If there is a SLG on transformer secondary, should 87 detect it?

We say the transformer inrush is 12X FLA. FLA = MVA/Sqrt(3)/kV*1000 => FLA is the FLA RMS current So the RMS value of the inrush waveform should be 12X FLA RMS or it is the maximum of the inrush waveform (Imax) is 12X FLA RMS? I mean is the inrush current maximum or RMS? What is the length of...

I have seen an Excel sheet calculator that computes the current at the transformer primary and the secondary when various types of faults are applied. Have you seen this calculator? If you have seen it, can you please direct me to this calculator or send me a copy?

Can you please advise how to coordinate a breaker at the transformer secondary with the primary? How to size the primary and secondary breakers?

Can a secondary transformer breaker protect a transformer? or it is only a relay in the transformer secondary can open the upstream primary breaker ? Do we need a coordination between primary and secondary breaker? Does the secondary breaker protect the thermal curve of a transformer?

TL line capacitance is given in "uS/km". I need to convert this to "mohm.m" in Digsilent software. The line is 200 uS/km so I convert it as 1/200 Mohm/1000 = 0.000005 Mohm.M. This does not make sense. Can you please help me with the conversion?

What does it mean 10x @ 0.1s? It means the current maximum (top wave point) will go to 10 x FLA and it lasts 0.1s, right? So the maximum point is 10x FLA, no need to divide it by sqrt(2). Can someone confirm? Is there a reference of transformer size and inrush value? Can it really go to 25X?

Is there a way to convert a CYME database to PSS/E?

The use of power electronics pushes the use of EMT software compared to other RMS software. I use EMT simulations frequently. I am interested in the syllabus and if there is a web link to your class, please share.