Isolation Transformer

[Love4sound]

Check between the R and Y, Y and B and B and R. the terminating cables on the DB or the busbars have the colours to indicate this.

Check at the distribution transformer? Or at the distribution box at my flats? And also how to check line voltage between each phase?

L-E voltage difference is an indication of a fault on the LV distribution network of your area.

LV distribution network is by the distribution transformer where the neutral line is grounded. Hope I got it right? If so I am also suspecting the same and requesting EB to check and confirm. But they are not educated enough to understand this issue. They are just not qualified enough. They keep repeating the same that if issue from EB side all will face problems and will be complaining.

 

[Subbu68]

Check at the distribution transformer? Or at the distribution box at my flats? And also how to check line voltage between each phase?

LV distribution network is by the distribution transformer where the neutral line is grounded. Hope I got it right? If so I am also suspecting the same and requesting EB to check and confirm. But they are not educated enough to understand this issue. They are just not qualified enough. They keep repeating the same that if issue from EB side all will face problems and will be complaining.

Check between each Phase to Neutral and between each of the Phases. They should be marked R, Y, Blue and Black.

I can understand the logic of EB fellows too.

If you have eliminated your house skip to below steps. Else switch off each circuit MCB at your flat (if wire fuses pull out one by one) and measure at the incomer of the DB to your house. That could weed out the culprit if in your house.

I have to make a guess about the power connection at your place. I assume it is at 415V, 3 phase to your building and fed with overhead lines.

The measurement is at the distribution box (board) or DB.

• Switch off supply to your house first. Easily done as you don't have to convince anyone. Do the measurement at the incomer of the DB. If still the same proceed to next step. If the voltages are restored to normal then the cable, connection points or even the MCB between your house and main DB could be the issue. Cables could have been chewed by termites or rodents and creating a high resistance fault that does not blow the fuse or trip the MCB.
• Next "Mama, I will switch off the supply to your house for 5 minutes - anjae, anju nimisham" and flat common area supply one by one. If any of this exercise brings sanity to the voltages you got the source of trouble. Educate them of the danger to their kids or elderly or themselves as the measured N-E voltage is enough to kill them. "konjam bhayameduthungo". They should repair it.
• If these fail, switch off the supply to entire flat. Measure at the incoming point at the DB.
• If it fails the EB network can be suspected. You have a case with TNERC.
• If possible measure at DB of your neighboring plots troubling them with a shutdown for a few minutes or even without that. Could be from any of them. Need not be each individual house, just each plot.
• You had written the voltages are fluctuating in different phases. If fed by overhead lines, check for any tree branch brushing the lines in the area fed by the same transformer. It may be on one phase or between phases. This is the general cause of high resistance faults in distribution systems with overhead lines. If possible push off the tree branch with a dry bamboo stick. Don't touch the tree. You can also stick the multimeter to the tree trunk and ground below to test.
• If cable fed, it could be the cables in the network. EB have to eliminate the faulty cable by switching off the feeders one by one .
• I suppose you cannot access the transformer - usually fenced off. If the EB line man "co-operates" isolate the low voltage side and measure at the incomer to the main DB there. If the individual feeders to the neighborhood buildings can be switched off at the post or the substations you could precisely point fingers. Be careful not to access the high voltage side. You could be blown. You can identify it with 1R, 1Y, 1B (or A, B, C) and larger insulators and thinner wire connections or cables with a red or black heat shrink sleeve on them. Low voltage can be marked by 2R, 2Y, 2B and 2N (or a, b, c, yn) and smaller insulators and colourful R, Y, B, Blk cables.

Assuming you did all that and caught the issue, a technician with an insulation tester (Megger as it is lovingly called by all - though a brand) and "megger" the cable or circuit. It should show in several Megaohms if healthy. If not there is some fault in that cable or wire.

If the flat is supplied from own transformer then do this procedure till your transformer Low Voltage side. High voltage side is generally EB business.

Hope I did not overwhelm you.

 

[keith_correa]

There will be an Ombudsman who will be the body that will need to be approached if your grievance is not resolved. You should do that asap. Send the EB a legal notice - a lawyer will charge you probably 2 - 3K for this. Mention in that notice that in case of any mishap due to the line problems, the EB would be responsible. Also, mention your previous complaints and non cognizance of the complaints by them.
Your previous complaints - have they been in writing or verbal. If verbal, you can kick and scream all you want, nothing will happen. Tap the Indian aversion to a complaint in writing. Get their response in writing. Giving/Receiving something in writing scares the shit out of Indians for some reason.

 

[Subbu68]

There will be an Ombudsman who will be the body that will need to be approached if your grievance is not resolved. You should do that asap. Send the EB a legal notice - a lawyer will charge you probably 2 - 3K for this. Mention in that notice that in case of any mishap due to the line problems, the EB would be responsible. Also, mention your previous complaints and non cognizance of the complaints by them.
Your previous complaints - have they been in writing or verbal. If verbal, you can kick and scream all you want, nothing will happen. Tap the Indian aversion to a complaint in writing. Get their response in writing. Giving/Receiving something in writing scares the shit out of Indians for some reason.

There is no need for a legal notice. There is Electricity Regulatory Commission who is the Ombudsman for this sector in every state I believe.

TNERC have a complaint procedure and it is logged in their system.

Verbal will not work if done personally but to the Call Center may work as it is recorded in most places.

But before doing it the FM should make sure it is not his fault or of others in the building. OR regulators (myself included) can come back on you

 

[Love4sound]

Check between each Phase to Neutral and between each of the Phases. They should be marked R, Y, Blue and Black.

I can understand the logic of EB fellows too.

If you have eliminated your house skip to below steps. Else switch off each circuit MCB at your flat (if wire fuses pull out one by one) and measure at the incomer of the DB to your house. That could weed out the culprit if in your house.

Yes we have checked each stages step by step. Our apartments have 5 houses so we disconnected the MCB at the DB of our flat and took readings. The Distribution transformer for out flat is powering around 25 apartments. So i randomly picked 10 apartments which all have individual earthing but all 10 had the same N-E reading 20-50V. I find it odd all 10 apartments have earthing or wiring faults

There will be an Ombudsman who will be the body that will need to be approached if your grievance is not resolved. You should do that asap. Send the EB a legal notice - a lawyer will charge you probably 2 - 3K for this. Mention in that notice that in case of any mishap due to the line problems, the EB would be responsible. Also, mention your previous complaints and non cognizance of the complaints by them.
Your previous complaints - have they been in writing or verbal. If verbal, you can kick and scream all you want, nothing will happen. Tap the Indian aversion to a complaint in writing. Get their response in writing. Giving/Receiving something in writing scares the shit out of Indians for some reason.

Do government employees really care or bother about legal notice? I spoke with few contacts in other location EB and they all advised unless the EB is convinced there is an issue no other steps will lead to a solution. Complaining,notice etc nothing will work. They will just close the case as only one member from the entire community complaining and its an individual problem. Tomorrow if EB comes and asks a written statement from other members in my community if there is an issue all will sign that there is no power issues which EB will us it against me. Yesterday when i met with 6-7 line man who all gathered for a work in my location one guy was mocking me this guy eh he is been simply complaining for 3 months and that i am also instigating others in the area that there is a problem when there is actually no problem. Fate of a common man in india. I mean some one educated like me getting mocked by illiterates for being right.

 

[Love4sound]

@mods @Nikhil @arj @captrajesh

Please move the discussion from comment number 6 to the below thread. Lets all continue the conversation there. Lot of good points and will be useful in the right thread. This thread is on isolation transformer alone.

My earthing is screwed

Dear Fm’s As the title suggests my earthing is all messed up. Neutral to earth reading as per IEEE standard should not exceed 3 volts for homes and 5 for industrial. Mine is always around 15-30. I contacted vertex and had their electrician inspect my grounding. As per his suggestions we...

www.hifivision.com

 

[keith_correa]

But before doing it the FM should make sure it is not his fault or of others in the building. OR regulators (myself included) can come back on you

All this testing downstream of the DB is just academic, useful to know but is not upto a consumer to test and check. Our job is to complain (relentlessly and thoroughly) and their job is either to rectify the problem or to tell the aggrieved party formally that the issue is not due to a fault from their side.

Do government employees really care or bother about legal notice?

You will be surprised how fast they will jump. If you word a complaint properly and politely they will act. They will of course resist (it's the nature of the beast) but they HAVE to act.

I spoke with few contacts in other location EB and they all advised unless the EB is convinced there is an issue no other steps will lead to a solution. Complaining,notice etc nothing will work. They will just close the case as only one member from the entire community complaining and its an individual problem. Tomorrow if EB comes and asks a written statement from other members in my community if there is an issue all will sign that there is no power issues which EB will us it against me. Yesterday when i met with 6-7 line man who all gathered for a work in my location one guy was mocking me this guy eh he is been simply complaining for 3 months and that i am also instigating others in the area that there is a problem when there is actually no problem. Fate of a common man in india. I mean some one educated like me getting mocked by illiterates for being right.

You can think about "what if's" or you can do something about it. I say go after them. I've done this with government departments in the past and escalated appropriately when needed - in the end I've got my work done which is all that mattered.

Have you tried an RTI with pointed technical questions? I'm sure many here would help you with the questions. Do it!

 

[ssf]

When my BSNL provided UPS for the BSNL fiber modem had it's battery go dead, BSNL replaced it with a box without a battery backup. When I called BSNL, the person on the other end of the line told me that there is a shortage of battery and that I am another customer in line and will have to wait. I told him that this is the kind of attitude that give govt departments a bad name. He started to abuse me. I disconnected the call and put in a strong complaint at the BSNL grievance site. A new UPS with a battery was delivered to me in 3 days.

So, complaints and escalations do work in Govt. departments. I work for a govt organization coming under the Shipping Ministry and we take complaints from our Agents seriously.

 

[keith_correa]

All this testing downstream of the DB is just academic, useful to know but is not upto a consumer to test and check.

Typo! I wanted to say "Upstream" - looking at it from the consumers end.

 

[Subbu68]

@Love4sound

I think things are a bit more clear but if my understanding is wrong please correct it.

Is it a compound / community served by one transformer and you tested in 10 apartments the N-E voltage?

If the transformer is owned by the community then the onus is on your association. I am drawing example from my apartment in Kerala. The assets beyond the HV isolator is owned by the owners of the apartments. Utility stop at the isolation point on the high voltage side. The association takes care of the maintenance of the HV cable, transformer, Low voltage panel and beyond. Please see picture inserted below. It is my understanding of the arrangement at your place. DISCO means Distribution Company and User is you

That is the general principle of asset ownership all over the world. They will not touch the assets of the consumers - be it be individuals or a community.

If like the above, the transformers are delta connected on HV side where EB will supply at say 11kV. Star connection on LV side with a neutral. The issue of unbalanced load, high resistance faults do not get carried over to the EB side.

• Disconnect each building in the plot and measure the voltages and try to isolate the fault.
• Check the neutral connection of your transformer and it's neutral earthing pit not the body earth / safety earth. A high resistance there could raise the voltage due to unbalanced nature of residential loads.

 

[Love4sound]

@Love4sound

I think things are a bit more clear but if my understanding is wrong please correct it.

Is it a compound / community served by one transformer and you tested in 10 apartments the N-E voltage?

If the transformer is owned by the community then the onus is on your association.

Yes by the same transformer but owned and maintained by EB. We do not even have an association for our apartments. From the transformed each flats are supplied and individual connection through the EB post

If like the above, the transformers are delta connected on HV side where EB will supply at say 11kV. Star connection on LV side with a neutral. The issue of unbalanced load, high resistance faults do not get carried over to the EB side.

• Disconnect each building in the plot and measure the voltages and try to isolate the fault.
• Check the neutral connection of your transformer and it's neutral earthing pit not the body earth / safety earth. A high resistance there could raise the voltage due to unbalanced nature of residential loads.

Yes the transformer is delta connected on the HV side and star connected on the LV side which is where the neutral line is taken by grounding it on the transformer end. The highlighted checks is what i am requesting the EB to do but they are not willing to do so. This myself or any electricians cant do as it is EB managed and maintained.

 

[Subbu68]

Then the only recourse is to use the channel as per TN Electricity Regulatory Commission document I had pointed to in the PM.

 

[Shinto]

Is there a possibility to engage a local Electrical Engineering Consultancy to look at this problem(might be a costly exercise). They can locate the problem and also liaise/convince the authorities if the problem is found to be on their side.

 

[Love4sound]

Is there a possibility to engage a local Electrical Engineering Consultancy to look at this problem(might be a costly exercise). They can locate the problem and also liaise/convince the authorities if the problem is found to be on their side.

Not sure if one such consultancy or service is available in Chennai.

 

[Subbu68]

Not sure if one such consultancy or service is available in Chennai.

Try this person

[email protected]

His name is Mohan. He runs a consultancy. If not the work he'd be able to guide you. He was my senior in L&T.

 

[Subbu68]

Another is Muthukumar

[email protected]

We worked together at Mott MacDonald in Abu Dhabi

 

[Love4sound]

Try this person

[email protected]

His name is Mohan. He runs a consultancy. If not the work he'd be able to guide you. He was my senior in L&T.

Another is Muthukumar

[email protected]

We worked together at Mott MacDonald in Abu Dhabi

Thanks for the contacts. Will check with them later. For now I have planned to test an isolation transformer. Also going to have new earthing installed even though not required. EB keeps dodging it has earth problem and I decided why not spend on new earthing. Let’s see what’s their excuse. I spoke to AE and said just for EB I am installing a new earth and will not connect it to our flats so they can check their open line directly with the new earth line.

 

[Subbu68]

Hi Navin

From your measurements and some research it looks like there is a high impedance earth fault in the phase that shows lower L-E voltage and Neutral at the transformer is not properly connected. Could be some loose contact.

Best of luck with EB

See link

Reason for High voltage difference between Ground and neutral wire in 3 phase system

I have following reading of voltages: RY 397V RB 398V YB 393V RN 231V YN 227V BN 228V RG 386V * YG 385V * BG 10V * NG 216V * If you clearly observe data above phase-to-phase voltages are

electronics.stackexchange.com

 

[Love4sound]

Got myself a 5kv isolation transformer from vertex which solved my N-E V fault. The cabinet quality is no way near the servo stabilizer which is now laying idle and will be sold shortly as I am now using my system only connected to isolation transformer

 

[vbutani]

Got myself a 5kv isolation transformer from vertex which solved my N-E V fault. The cabinet quality is no way near the servo stabilizer which is now laying idle and will be sold shortly as I am now using my system only connected to isolation transformer

Do isolation transformer work as voltage stabilizer as well? I don't know any technical details about it.