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If the transformer is built as per IEEE/ANSI or NEMA instructions -certain materials and dimensions-if the ambient temperature is lower you may overload in a way the transformer without reducing its life. The same, on a transformer built as per IEC standard you have to reduce the load if the...

In my opinion, the OP required: What is the short circuit current contribution by all these Inverters at the MV bus level? I agree with Parchie: 1.5 times the rating may be the maximum. Then, 300 inverters in short-circuit case supply 1.5*1.1*300=495 MVA It will be the System power from the...

I never worked with lithium battery for power supply. I used only lead acid open vessel of 220/360 Ah for control in power stations. The lithium battery was for iPhone only. However, to start a discussion, I drew a possible charging and distribution of 300 units of 1 MW 480 V lithium batteries...

Before 50 years I used oil filled cables [low pressure oil] of 110 kV. The pressuring equipment -pumps, conduit and meters were supervising required, also. I think there are today manufacturer for XLPE cable insulation as ABB, Siemens, Nexans and others. A problem is the cable tray. You may...

DESIGN MANUAL FOR HIGH VOLTAGE TRANSMISSION LINES U.S. DEPARTMENT OF AGRICULTURE

Electrical Transmission and Distribution Reference Book by Central Station Engineers of the Westinghouse Electric Corporation EAST PITTSBURGH, Electric Power Distribution Handbook by T.A. Short and many other..

I agree with Raghunat. In my opinion also, the cable shields of three phases insulated cores was open-not earthed-at one end but earthed at the other end, and the 65V was measured between one shield and the Earth. In this case a capacitive voltage divider was created and the 65V was the part...

NEC 2013 250.94 Bonding for Communications Systems. (A) The Intersystem Bonding Termination Device. An intersystem bonding termination (IBT) for connecting intersystem bonding conductors shall be provided external to enclosures at the service equipment or metering equipment enclosure and the...

I agree with waross : you need only the last transformer impedance and the low voltage feeder to CB, if you need the three-phase short circuit current at CB [400V] busbar- then the base voltage is 0.4 kV. The System impedance will be 0.4^2/Scc=4.57E-6 ohms According to IEC 60909-2 the...

From IEEE 80/2023: https://files.engineering.com/getfile.aspx?folder=a43682d3-cd3b-4866-94a2-3c2f5239fd9e&file=GPR_IEEE_80.jpg

If it is about to Continuous Cross Bonding, then in this system the sheaths are cross bonded at the end of each minor section throughout the whole cable route. The three sheaths are bonded and grounded at the two ends of the route only. In each minor shield section is a build-up voltage. The...

I agree with the idea of a single point grounding for local equipment-except for the bonding connections. NEC Art. 250, it recommends -indeed-to proceed in such a way with grounding and bonding connections that the objectionable currents will be avoid. However, it is not so clear how to proceed...

I agreed with Che.

BS7671 Table 4C6https://files.engineering.com/getfile.aspx?folder=c8d90a00-ed94-46a4-86e3-8066bc9e9bd4&file=BST671_Table_4C6.jpg

BS7671 Installation Method 120https://files.engineering.com/getfile.aspx?folder=cf32a910-c849-44d2-8b17-5032e6069418&file=BS7671_120_Installation_Metod.jpg

In my opinion, the IEC 60364-5-52 standard it is only for information. The actual standard- which is compulsory in each country is more specific. For instance, BS 7671-I have only 17th edition [2008]-Table 4A2 for installation methods from 118 up to 120, for cable enclosed in trench or in an...

As it is declared somewhere in the text, the calculation in IEC 603564-5-52 standard follows the IEC 60287 way. So, in my opinion, the 51 item is according to the volume 60287-2-1 chapter 2.2.6.2 Unfilled troughs of any type, with the top flush with the soil surface and exposed to the free air...

Few remarks: 1) the trough[or concrete tray] is closed with a concrete plate[ a lid] only. 2) the plate is exposed [to free air but to sunshine also?] 3) if it is embedded, how deep? If we decide to neglect the sun radiation then Reference method D, item 70 of table 52-3, (multi-core cable in...

See: ABB Calculation of Short-Circuit Currents in Three-Phase Systems http://at.dii.unipd.it/renato.gobbo/didattica/corsi/Componenti_tecnologie_elettrici/ABB_swithgear_manual_E11/ABB_11_E_03_druck.pdf

As far as I know, the neutral is not, always, a CPC conductor also. The standard IEC 60364 [ all the parts] it is only for up to 1000 V a.c. and 1500 V d.c. In chapter 11 of the part 1 of this standard is written: 11.2 It covers: a) circuits supplied at nominal voltages up to and including 1 000...