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Hi everyone, there is a question need your help. 33kV underground XLPE cable, 2000mm2, the length are 20kM. If we need to consider reactive compensation, how to size/calculate the capacity of shunt reactor? Are there any textbook or standard we can refer? Thanks all.

Hi, I find an image in the website accidently about the harmonic issue. This image mark the direction of triple order harmonic. So, I curious and wonder to know their direction if lost the neutral line or add grounding wire. Please find the five(5) schematic as attached and advise these...

Hi, In 3φ4W power system like 208/120V and 416/240V, G and N wire need to take care. There are 4 connection cases between G and N wire as attached. Please advise which one is practice connection and their pros and cons. Any guideline or article that I can refer to ? Thanks for your advice. Have...

Hi, Please advise when undervoltage Relay (27) Shall be trip the CB or just alarm only? What is need to concern? Is there any criteria for following? Thanks. ciy

Dear all, There is a three-winding transformer rated: 345/13.8/6.9 kV transformer; 92/54.5/37.5 MVA The impedance percentage of PS/PT/ST is 16/13/1.9%. Please advise how to draw its damage curve? What is the difference between the 2 winding and 3 winding transformer? Thanks for your help in...

Dear ALL, I met an issue need help that is how to design and plan an induction generator (IG) in chemical plant. Normally, I always find Synchronous generator (SG) in the plant. What is the main design concern between IG and SG? Is there any IG design guide or reference can lead me to...

Hi, Sometimes, I propose my quotation of power system studies to my client. They might ask me how to get the amount of price, even ask me what the basis of your quotation is. I always explain that would spend how much hours and cost per man hour(MH), so get it totally. Like this is a personal...

Dear All, Please find the attached, there are two (2) one line dia. Case A and Case B separately. Case A, this is a scheme from someone project that I study recently. The secondary side of transformer is ungrounded of Wye connection and equipped with Lightning arrester (LA)...

Dear all, There is a transformer need to add the other differential relay (87T2) for redundant. As I know, the practice connection is the separate as attached figure 1. The 87T2 in series with 87T1 as figure 2 is not a good solution, however, no other CTs are available...

Dears, I would like to build the SPAM 150C Curve in the SKM. But, it seem not so easy. Please advise if you have any suggestion or experience! Thanks in advance! Stanley

Hi, There is a relay setting question need to ask for help. That is related to the instantaneous current setting (50). For example, the known fault current value is 10000A, the said setting should be larger or smaller than 10000A? Which one is better protective...

There is a differential relay of generator placed on GCP. The both CTs of differential relay, one in the 13.8kV SWGR and the other one located at secondary side of generator. There is a question that the length of CT lead from 13.8kV SWGR to GCP (eg. 1000M) is far longer than from Generator to...

There is a concept need to clarify, that is How to determine the power factor when I select a generator set? I find some cases about the power factor, it is always 0.8 or 0.85. What is the difference between them? What is the key point to select the power factor? Thanks for your advice in...

There is a power system, one Generator connected to 13.8kV Bus and one Step-up transformer 69/13.8kV primary side connected to the power grid, secondary connect to 13.8kV Bus. Both generator and transformer have equipped with NGR for forming a low resistance grounding system. Choose one of two...

I would like to record macros with shapes. When I done the shapes (eg. Two circles to form a transformer symbol), then group them as finish. Next time I want to get the transformer symbol in group, just pick the dedicated macro up. But, the work isn’t so smooth expectedly. The said macro can’t...

Hi, I have a question need some advice. There is a MV/LV transformer upstream from MV SWGR. However, the transformer and MV SWGR located at different room. My question is : Take care the safety and cost reason. Do I need to prepare another MV breaker at primary side of transformer to...

Hi, I run the short circuit in SKM. And, I fill in the SCC contribute from Utility in MVA as below. 3 phase = 8000MVA Line to Ground= 3000MVA I got the kA value from SKM are 20.082kA and 22.654kA base on 230kV respectively. If(3p)=MVA(3p)/(1.732*VL-L)=8000/(1.732*230)=20.082kA---OK...

Hi, Happy Holiday to Everyone! I heard about the term of “weak power system” from somewhere. How to define the said “weak”? Please help! Thanks!

Dear All, There are three phases power wire between two gantry in one AIS. For the safety reason, I would like to figure out what is the adequate sag is needed. Data as below, OHL – All Aluminium Conductor (A.A.C) 795MCM Span – 30M Max. Horizontal tension = 1000 kg Max. Wind speed – 40m/sec...