Recent content by wonderchi

Let me rephase my question: I am to install a STS (static transfer switch), in the upstream we only have one supply and one generator...I am planning to use a 3 pole STS instead of a 4 pole STS...(since we dont need to switch the neutral because there is only one generator)...Am I right...

To do with Tier 1, 2, 3, 4 requirements? When dont you need to switch the neutral??

Hi, Can someone clarify for me...when can we select a 3 pole STS over a 4 pole STS unit? Thanks Allan

Thanks for that..as with naming convention..what is the best/recommended naming of double neutral... e.g 5 *1C 185mm^2 + E (XLPE/PVC) CU cable or e.g 3 *1C + 2N 185mm^2 ...etc

Hi, I am wondering if anyone can give me advice on when to use double netural cables for building services: eg...data centres (with harmonics) is the only one I am thinking about. To take it to the next step...what is the deciding factor of using double netural cable and how you can calculate...

HI, Does anyone have a link to a spreadsheet to sizing swithboards and cables. Thanks

For confirmation: Steady state fault analysis give you the maximum and minimum fault current that can be reached. So what does transient fault analysis give you? Thanks

Is it true that only recently breakers are rated for symmetrical amps and a maximum x/r? Because there are still lot of books still refer to asymmetrical rms values.

Thanks jraef But why whould the manufacture publish symmetrical interrupt ratings and not asymmetrical? Since symmetrical current is found in steady state and asymmetrical is the transeint part in the short circuit currnet with the sum of DC component. Hence asymmetrical is usually bigger then...

Waross, Thanks for you post, however wht you telling me i already know...no need to search the forum. Wht i want to know, which i am still not getting it, is that: By using SKM, I obtained an asymmetrical rms value of 50kA at 0.5 cycles, and then I look at my circuit breaker it tells me Imax...

Hi, I looked at a few circuit breaker catalogs and I want to verify what the catalogs are saying: For a 630A circuit breaker at 11kV network, the Ip or Imax is 50kA. Is this value the rms value or the peak value? Thanks

Can you expand more on the purpose of minimum currents for protection settings. thanks

Hi, I am performing fault analysis to rate protective equipment in one of our stations. Is it necessary to find the minimum fault current? My point is, isnt true that you only want to know the maximum fault current so your protective equipment can be rated above this level. So how does...

Hi, the above question should be made clear as follows: I know that from steady state fault analysis, it gives you the maximum and minimum fault levels which sets a benchmark for rating protective equipments. But how will fault 'transient' analysis help in rating protective equipments.

Hi, I am performing fault analysis using SKM. Books often associate fault methods by finding thenevin equivalent and then using ohms law to find the fault current. And thats what i have been doing. Are the results then steady state values. If so, how would transient analysis come into fault...