Home Technical Articles Engineering Literature Substations EE Tools Get access to premium HV/MV/LV technical articles, electrical guides, research studies and much more! Premium Membership PLC Training advertisement MORE INFORMATION Energy and Power / Metering Electrical Thumb Rules You MUST Follow (8) By jiguparmar | March, 10th 2014 | 12 comments | Save to PDF Share! Home / Technical Articles / Electrical Thumb Rules You MUST Follow (8) advertisement Three EE thumb rules to follow: 1. 2. 3. Accuracy Class of Metering CT Accuracy Class Letter of CT Accuracy Class of Protection CT Stop 📃 Electrical Electrical Thumb Thumb Rules Rules You You MUST MUST Follow Follow (Part (Part 8) 8) Continued from part 7: Electrical Thumb Rules You MUST Follow (Part 7) Accuracy Class of Metering CT Metering Class CT Class 0.1 To 0.2 0.5 3 3 OR 5 Applications Precision measurements High grade kilowatt hour meters for commercial grade kilowatt hour meters General industrial measurements Approximate measurements Go back to Index ↑ Accuracy Class Letter of CT Metering Class CT Accuracy Class Applications B Metering Purpose Protection Class CT C CT has low leakage flux. T CT can have significant leakage flux. H CT accuracy is applicable within the entire range of secondary currents from 5 to 20 times the nominal CT rating. (Typically wound CTs.) L CT accuracy applies at the maximum rated secondary burden at 20 time rated only. The ratio accuracy can be up to four times greater than the listed value, depending on connected burden and fault current. (Typically window, busing, or bar-type CTs.) Go back to Index ↑ advertisement This site can’t be reached Accuracy Class of Protection CT Class Applications 10P5 Instantaneous over current relays & trip coils: 2.5VA 10P10 Thermal inverse time relays: 7.5VA 10P10 Low consumption Relay: 2.5VA 10P10/5 Inverse definite min. time relays (IDMT) overcurrent 10P10 IDMT Earth fault relays with approximate time grading:15VA 5P10 IDMT Earth fault relays with phase fault stability or accurate time grading: 15VA Go back to Index ↑ advertisement Related EEP's content with sponsored links This site can’t be reached The connection was reset. Try: Checking the connection Checking the proxy and the firewall ERR_CONNECTION_RESET Check your internet connection. Check any cables and reboot any routers, modems, or other network devices you may be using. Allow Opera to access the network in your firewall or antivirus settings. If it is already listed as a program allowed to access the network, try removing it from the list and adding it again. If you use a proxy server… Check o r pro settings or contact o r net ork administrator to Premium Membership Premium membership gives you an access to specialized technical articles and extra premium content (electrical guides and software). GET PREMIUM NOW ⚡ Jignesh Parmar Jignesh Parmar has completed M.Tech (Power System Control), B.E (Electrical). He is member of Institution of Engineers (MIE), India. He has more than 13 years experience in transmission & distributionenergy theft detection and maintenance electrical projects. 12 Comments THANKS SIR, VERY NICE MATERIAL FOR PRACTICAL KNOWLEDGE IMPROVEMENT AJAY DAMOR (reply) (reply) D DE EC C 2277,, 22001188 How to prepare ELECTRICAL BOQ ? Can you pls help ? Do you have some study material or book on that. URGENT ! Loveleen M MAY AY 0088,, 22001188 (reply) (reply) thanks sir, your articles helping me to boost my kowledge. Nagaraja (reply) (reply) O OC CTT 2255,, 22001155 Thank you for providing such important information which will help to update my knowledge. Milind M MAY AY 2266,, 22001155 (reply) (reply) Thanks Jungesh ..Keep it up. Good stuff .. Ahmed Eltayeb (reply) (reply) JJU ULL 2244,, 22001144 thanks Jignesh sir, for giving us the information about electric thumb rules. Niraj Patil i want help from you, JJU ULL 2211,, 22001144 can you give me a thumb rules for the use of estimation and costing of electrical project work ? (reply) (reply) Great electric engineering. Sushil Sasane (reply) (reply) JJU ULL 1188,, 22001144 Please send newsletter ANKIT JANGID (reply) (reply) A AP PR R 2211,, 22001144 Dear Jigu Sir, Good and Thank you so much. It is use full for us. Sasikumar M MA AR R 2277,, 22001144 (reply) (reply) I wanted to query the last part of your article regarding the accuracy class of protection CT’s. What was the intention of this part of the article? Prakash M MA AR R 11 11,, 22001144 Is it to give one an idea as to how to select CT’s? To my knowledge, the CT ratings are dependent on the fault level of the application, this is one of the determining factors for the CT sizing. If you have some time, please look into writing an article on this topic as well. Thanks once again. (reply) (reply) Your materials are very useful. How do I download them? Keep doing the great job. Gife M MA AR R 1100,, 22001144 (reply) (reply) You can find “Get PDF” Tag on middle left og the webpage,by clicking on that you can have pdf copy of what u want…have a great day Dhaval M MA AR R 11 11,, 22001144 (reply) (reply) Leave a Comment Tell us what you're thinking... we care about your opinion! 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