substation equipments

please help..It is very important for the substation design engineers particulerly for the beginners

What is HCB HDB pantograph ? It sounds fantastic ! What Voltages( V, KV.) and Power (KVA/MVA)or Current (A, amp,ampere) are involved in the substation? These are the minimum imformation required before others can start to help you.

Regards,

Khor

Dear Mr khor thanks for your reponse.the requirement once again elaborated herein:- I have asked for a details and types of substation equipment.lets say isolator used in different voltage level starting from 11 kV to 400 kV. what are the types of isolators are available in market? What are the parameters that decides the types for different voltage grade? Same for CT, CVT, Breaker, PT, wave trap etc etc Hope I am able to make you understand. Now waiting for your response

Dear sarawata1981,

I am experienced in the 6.6kv to the 33kv range of power system and equipment.To start with you need to find out the few conditions that the supply authority may impose on any consumer who is connecting to and receiving supply from their source.These usually include :-voltage level,for example 11kv,short circuit level,18.4 to 20 or 25 ka in 3 second ( sometimes it is in 350MVA,or 500MVA ),under ground or overhead supply lines available to your project,types of conductors,bare cu/alum overhead hv lines,insulated Arial bundle hv cables,under ground insulated cu/alum cables such as paper insulated lead covered steel taped and served (PILCDSTAS),XLPE/STA/PE--Cross link polyethelene steel tape or steel wire or aluminium wire armouring and PVC or P.E. served (outer sheath), 3 core or single core cables.After knowing these,find out the amount of power that you can have from the source.Usually the supply authority can give more power at higher voltage level,i.e. you are allowed to take more at 33kv than say at 11kv as the consumer is paying more for the capital costs and 415V or 11 kv is kept for the smaller clients.

The purpose of an isolator switch is to ISOLATE a section of the electrical circuit from another circuit. It is not made for frequent switching of normal current.The construction is simple and is usually using flat copper Knife switch ( the swing/throw moving part) and a spring loaded flat receptor ( stationary part).Many engineer wrongly regard it as a load break switch,LBS ( which has a secodary,self sacrificing,smaller arching contact that save the main contact of the knife switch from electrical wear.) Isolator is the cheapest switchgear.

(1)If you have overhead 11kv supply line you may be allowed to use "pole mounted isolater switches with or without fuses designs.The rating example of these isolator switches are:Type: 3 pole (normally) or single pole outdoor type(I have not been to America but looking at some pictures and reading some of the forum writings,they have and allow single phase 11 or 22 kv supply intake);Current rating in ampere,short circuit rating in KA and time withstand, 1 sec or 3 sec.; Insulation at 11kv/28kv/75kv which means it is to be used on 11kv lines,it can withstand 28kv for 1 minute at 50hz(one minute power frequency test ),75kv (BS,IEC)or 95kv (ANSI,American standard ) peak or lightning withstand voltage test which is a transcient peak voltage,spike that is a few cycle.In America,and China there are some area where they have floating earth , the 11kv gears has to be rated with 95KVp that requires more clearances between phases and phase to ground thus cost more.The operation of the isolator is via a steel connecting rod and handle with insulators on the top.this rod is mounted on the pole that the carry the isolator.Some so called advance countries are still using a very primitive handheld pole to operated by a man on the ground.

(2) If you have only underground cable supply,Indoor 3 pole type in extensible or non-extensible panels.The cubicle,isolator switch,busbar and termination,control compartment can be either fully compartmentarised,metalclad,type tested switchgear or anything other than or lesser than these.Other specifications as per (1).

In some countries this kind of arrangement is not permisible due to the low and slow breaking capacity.

So far I have only briefly cover 11kv "Isolator".There are load break switches,Fuses,Circuit breakers (you can read what I wrote on the VCB and Sf6 CB comparisions in CR4),Ring main units,insulation types,mechinical and electrical interlocks for safty of operaration,foolproof and idiotproof on varous switchgears.Too much to type here.You can attend electrical exhibition to collect and learn these.

Are you in India ?

Best regards,

Khor.

Thanks for your consolidated reply.. I am in India..precisely in Kolkata..If you have more information/write up on that..please share in the below given email ID:-

thanks in advance

regard

Saraswata

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