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Hi What is the role of an electrical engineer in relation to specify wood or steel poles for distribution of power in as compared to a structural engineer. I have a riser pole from a substation yard that will be taking one 750 MCM cable and then it will be a run of approx. 1 km at 13.8 KV. I...

Hi, Could anybody advise me the advantages of having a surge arrester on secondary bushing of a transformer(44/13.8 KV) or the switchgear which is being fed from this. I think, the reasons could be on lines of switching voltage or lightening protection. I would appreciate a word. Thanks

Hi, I have a situation, where I might have to consider(As advised by Sr. guys) connecting a new substation ground grid( Grid A) to a near by existing grounding grid(Grid B). The near by existing grid has no surface installation and is connected to another substation grid( Grid C) located at a...

Hi, This is my first question on Motor forum. I was wondering, can I use a 60 HP fan motor on a size 5 NEMA starter which is good between 100-200 HP motors. Actually, the client does not want to buy a new starter and wants to use same starter when he is done with 60 HP fan application, he will...

Hi Everybody, I have this thread in two sections. This is related to a mine hoisting application and in some earlier threads I have seeked your suggestions and they were very useful. Now the project is with a company that is involved in mine hoisting applications design. We being the consulting...

Hi Everybody, I have made sure, that I am not asking a question that has been answered before. I had no doubts earlier about this problem before I spoke to few manufacturers. The application is a 4160 V 1250 HP Dewatering pump operating power factor .86. It is started using Direct on line...

Hi, I was a little hesitant in asking this question because I guess this aspect of grounding has been discussed many times. It is in relation to a mining application, where a 69/4.16 KV substation is feeding a indoor switchgear located in a Hoist-room, which has other electrical equipment also...

Hi, In one of the posts here, some body talked about Circuit breakers being faster in operation time than fuses. An engineer visited our office today and I happened to discuss with him about their facility policy about using Disconnects and Breakers for motor starters.His argument was that...

Hi All, Here are few numbers which I got from a client metering on the secondary side of two 44KV/4160 V transformers T1 and T2. T1; P= 3 MW Q= -5 MVAR S= 6 MVAR P.F= 52.2 % T2 P= 2.2 MW Q= .836 MVAR S= 2.3 MVA P.F= -94 % T1 means, 5 MVAR is the reactive power...

Hi, I am sure this topic must have been discussed many times here. I tried to search by using different key words but did not make it. You guys might be able to help. The situation is, I came across a single line diagram where my job was to attach an emergency generator 2 MW,4160 V. Now, I...

Hi, If any body has experience of running VFD with an emergency diesel generator. Do they cause any issues. It will be a vector controlled PWM four quadrant regeneratiev AC drive. I am just for any possibilities in general. Thanks

Hi, Is there a thumb rule that an emergency diesel generator can absorb real power that is certain percentage of its capacity. for example: 10 % of total rated capacity. We have this 1600 KW, 4160 V generator for mine hoisting application. The manufcturer told me that new generators being turbo...

Hi I am struggling to find some information about a thumb rule that might determine a particular application might require a Wound rotor induction motor or a squirrel cage induction motor and "HOW DOES IT EFFECT THAT A VFD CAN BE USED WITH THAT PARTICULAR MOTOR" We have a old used hoist motor...

Hi, We are selecting a softstarter for a mine ventilation fan application, I guess the decision was based on the manf. sales guy recomendations. He also mentioned that while using softstarter and VFD, it is not advisable to use capacitor banks. Can you kindly put a word to this. Regards,

Jghrist, I would appreciate an input from you on a situation. A 7.5 MVA oil filled transformer with fuses on primary side with a disconnect and a Vacuum breaker on secondary located at a distance of 15 ft from transformer inside a switchgear room. We will get the resistivity results of soil...

Hi, I read possibly all the threads on soft starts but my questions about soft starters still remain unanswered. In this part of the thread, I will just explain the background and a small question and as the project will progress I might have some more questions to ask depending upon the dilemma...

Hi I am seeking a basic advise in regards to rating for motors. For example I have a 200 HP motor rated at 575 V but the supply is 600 V. Now, normally at the panel where the motor is hooked might have 600 or 590 v. So, if I have to plug this information in a software package for a 600 v...

Hi Everybody.. I have to size a generator for a mine hoist. The mine hoist is 600 HP that means 600 * 746= 447600 W= 447 .6 KW For some moments of time, the load even becomes 847 HP during acceleration period of the hoist. But this period is in msecs. The calculations involved come with a...

Hi Jghrist, I could not find my answer so as per your suggestion, I am starting this new thread: If I have a 10 MVA transformer with 7 % impedance at 69/13.8 KV... The short circuit level at secondary is 5981 A and primary is 1196.2 A. When I know this is the possible primary short circuit in...

Hi Everybody, I had sneaked in an earlier post"Grounding in Rocky areas" and Jghrist was kind enough to answer my question there about the potential variation shown by dotted lines in fig. 1 found in the link below...