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Thank you so much dear slavag.

Hi everybody As you know in a substation automation system we read the metering information via modbus protocol,I would like to know that can we convert modbus to IEC61850 and then transmit the metering information to the system?

Hi everybody Is there any standard for availability calculation of substation automation system?

Hi everybody Because of special specification of sealed batteries I have never seen that this type of battery used in power substations.But I want to be sure that can we use this type of battery in power substation or not.Do you have any experiance about this?

voltage drop is 0.7%.it was my question,is it acceptable or not?should I use 4mm^2 cable or 2.5mm^2 is suitable?

Dear scottf our case is as follow: 400kv substation,400kv/110v CVT,burden of CVT is 10VA,secondary is connected to distance relay(7SA522)& metering equipment,total load is 6VA.lenght of cable is 300meter.We will use cable with 2.5mm^2 cross section.is it correct or not?

Dear scottf I'm so grateful for your reply. Do you mean that 1% or o.5% voltage drop is very identical and this can be more? we define the cross section of the cable as e.g 4mm2 and I didn't undrestand the 10AWG,IF it's posible please explane it more. thanks a million

Dear 7anoter4 CVT is not used to supply the equipment,motor,...is supplied from the DC supply of the substation or if they need AC supply,this provided from AC auxiliary supply of the substation.As you know CVT is used for protection relays and meters.e.g for input of distance relay,measuring...

Hi everybody I need to know the standard value of voltage drop in CVT cable calculation(is it 1% or 0.5%)

hi dear slavag our lines are parallel,we have coupler. It's clear that for short circuit lines it's so better to use line differential relay but there is an important parameter that we should consider,"PRICE".if we use line diff. we should use fiber optic cable and this increases the price.so...

Hi everybody As we know in IEC mentioned that because of keeping the accuracy,load of CVT should be 0.25% to 100% nominal burden of CVT anf If the load is less than 25% nominal burden,accuracy of CVT will reduce.I would like to know that is there any relashin beween load and accuracy,e.g if the...

Hi slavag Thank you so much for your help. Our line:cable line,4km,132kv,800A,without autorecloser,there are two line just between two substation,on the other hand this is end substation and is not in a ring of substations.

following to my question,would you tell me less than which distances we should use line differential protection instead of distance relay,e.g less than 10km or 5km or something eles.

Dear scottf,so grateful for your help.I thing we should use TPY class for distance protection in 400kv lines because of DC offset of the current.I don't know that should I do the rule mentioned in IEC 44-6 for Rct or not.I asked CT manufacturer about this but they said that there is no need to...

Thank you so much daer Slavag and lz5pl,hope you the best.

Thank you so much for your reply.It's very kind of you to tell me distance problem for protection of very short lines?According to cataloge,distance could do this but I don't know what is going on in practise.

hello everybody As we know according to technical data and catalogs,new distance relays can protect even very short lines(e.g less than 3km),so if in practis they can protect a very short line corectly,can we use them instead of line differential relay?

Thank you for your reply.In IEC 6044-6 standard there is an example for TPY class design,in this example mentioned that Rct should be less than 50% connected R to the secondary of CT.I would like to know that should we do this in our design or Rct is defined only by manufacturer and is not...

Hi everybody I would like to know that for protection relay CT requirement,is there any limitation for Rct in TPY class?