Showing posts from November, 2015


General Requirements And Importance Of Drawings-Diagrams For Underground Power Cable ProjectThe employer may engaged or contract with service-provider to execute an underground power cable project, service-provider actually carry out the whole works as per employer requirements. Here in this article we would like to focus on general requirements and importance of various drawings, designs and calculation sheet to execute an underground power cable project.

The term “drawing” should also included here diagrams, schedules, performance curves, and calculations etc. required for the comprehensive design of the works. The Service Provider should be responsible for the provision of all drawings required for the various stages of the Contract to execute the project.
All drawings, apart from workshop drawings, should be submitted to the nominated Engineer for his approval, in accordance with an approved program. The Service Provider should ensure that drawings are submitted for approval in pri…


What Is Lightning Arrester Or Surge Arrester?

In a simple and shortly we can say surge arrester or lightning arrester is a device used in electrical power system to protect others equipment from switching surges or high energy lightning surges.

If you are hearing the terms “lightning arrester” or “surge arrester” very first time and thinking, it’s like something “police arrest terrorist”! Yes, you not quite wrong; lightning or surge like a destructive terrorist for electrical power system, surge arrester works like a police man, catch it and send to ground before destruct the system equipment.
Don’t confuse lightning or surge arrester with lightning rod, surge suppressor or TVSS. Lightning Rod is a grounded potential device that divert the lightning surge; Suppressor is a lightning diverter device that uses in low voltage (below 1000V) system; TVSS is Transient Voltage Surge Suppressor used for divert the transient surge in low voltage (below 100v) system.

So as summary, we can say surge or …

চন্দ্র গ্রহণ ও সূর্য্য গ্রহণের কল্প কথা

দেশ-বিদেশর কল্প-কথায় চন্দ্র গ্রহণ ও সূর্য্য গ্রহণ বর্তমান বিজ্ঞানের যুগে আর কোন কল্প কথার স্থান নাই। প্রমান ছাড়া এখন আর কোন কিছুই যেন বিশ্বাস করা বা করানো সম্ভব না। কখনও এমনও ঘটছে যে বাবা-মা ও সন্তানের সম্পর্ক প্রমানের জন্যও বৈজ্ঞানীক প্রমানের প্রয়োজন হয়ে পড়ছে। মানুষ চাদের পিঠে গিয়ে দেখে আসছে, সূর্য্য সম্পর্কে জানছে অনেক অজানা তথ্য।
কিন্ত তার পরেও মাঝে মধ্যে জানতে ঈচ্ছা করে কল্প কথা, কল্প কাহিনী। আর তাই আজকের আয়োজন চন্দ্র গ্রহণ ও সূর্য্য গ্রহণের দেশ বিদেশের কল্প কথা। তবে এ লেখা কাউকে হেয় বা ছোট করার জন্য নয়; নয় কারও বিশ্বাসে আঘাত করার জন্য। শুধুই জানার জন্য। তাই সকলের প্রতি অনুরোধ কাউকে আক্রমন করে মন্তব্য করবেন না। 01. চন্দ্র গ্রহণ বা সূর্য্য গ্রহণ আসলে সূর্য্য ও চাদের মধ্যে যুগ যুগ ধরে চলে আসা বিরোধের জন্য ঝগড়ার ফল। গ্রহণের সময় মানুষেরা যখন ঘর থেকে বের হয়ে আসে দেখার জন্য, তখন চাদ ও সুর্য্য মনে করে পৃথিবীর মানুষরা তাদের ঝগড়া থামাতে আনুরোধ করছেন, তাই তো ঝগড়া থেমে যায়। আফ্রিকা মহাদেশের টগো ও বেনিন দেশের মানুষের মধ্যে এমন কল্প কথাই প্রচলিত।
02. চন্দ্র গ্রহণ আসলে কিছুই না, একটা চিতা-বাঘ চাদক…


What is Voltage Transformer (VT)?VT in abbreviation Voltage Transformer, on the other way PT or Potential Transformer is a transformer which convert voltage into standard measurable level. This converted voltage is then proportionally transform the measuring or controlling primary voltage. VT operates on the same principle as power transformer, different only purpose of uses. Unlike conventional transformer, voltage transformer have only one magnetic core attached with secondary winding. Physically VT [FR1]may constructed in single pole or double pole.
Voltage transformers shall comply with the requirements of IEC 186 with amendments and supplements-
Instrument Transformers-CT&VTTransformers which are used to instrumentation- like controlling, measuring etc. are known as instrument transformer. Instrument transformers are mainly used to coupling the main primary circuit and secondary controlling or measuring circuit.
Controlling or measuring devices are not capable to connect direct…


Armour Earthing Assembly for Wire Armour Single Core CableCable armour earthing is important for medium voltage (MV), high voltage (HV) and extra high voltage (EHV) system. Our discussion on this article is limited only single core plastic or paper cable wired armour earthing procedure for medium voltage (MV) system or 7.2 kV to 36 kV ranges.
The crystal clear step-by-step assembly figure shown the complete procedure of earthing system for wired armour cable.
If you follow the shown 9 step carefully, we hope you will be able to assemble the cable armour earthing successfully.
9 Step to Earth Cable Armour  
First of all remove the over-sheath according to the dimension given the appropriate manufacturer Installation Instruction, Remove the armour according to dimension as per shown in the drawing. Clean the end of the over-sheath for a length of 250 mm. Then slide the outer sleeve over the cable, and disassemble the clamping rings. Slide one clamping ring lug-downwards over the cable as sh…


Cable Installations Methods In Ground Duct & Cable Tray

The arrangement and method of cable laying both in ground duct and cable tray is an important factor to current carrying capacity and working performance of cable in its life time. Cables rating factors varies for air/ground ambient temperature variation, laying condition is a factor as such as

i. Ground temperature;
ii. Ambient air temperature;
iii. Depth of cable laying;
iv. Thermal resistivity of soil.

To protect the laid cable in future it also important to care on the location and procedure of cable trench excavation, ground strutting shuttering and pumping laying in backfill, specified quality protective covers drawing in ducts, reinstatement of the original surface without variation for type of rock shattered rock sand backfill footpath and roadway.

Cable may be laid direct in the ground with protective covers drawn into pipes or ducts laid in troughs or on racks or supported on trays or cleats as may be required as site sit…


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