What’s An Open Corner? - WHY is it Important? 🤔

Have you ever seen a transformer bank explode as soon as it is energized? In this video lesson we explore the importance of building and Open Corer on your Closed Delta banks. We talk about what it is, and how to use it to ensure that our transformer bank has no problems that could cause a fault.

[@lostbird25]

One of the best descriptions of phase angles and connecting xfmrs Ive ever seen

[@hilineacademy8482]

Thank you. I appreciate it. Stay safe 👍

[@eldenrivas7842]

Great video an explanation. Even a beginner can follow this demonstration! When will you be making more videos? Just came across your channel.

[@hilineacademy8482]

Thanks. I think I’ll have some time this summer to make some more. I took a full time training position at our JATC and I thought ide have more time but I don’t lol. Hopefully when the summer hits I’ll start up again. Stay safe 👍

[@benjurqunov]

Thanks for this video. Easy to follow refresher course for me. I never worked on utility side of anything, but I understand it. I' m retired Inside Wireman and Millwright of 36 years. Btw, On a former agri property, I'm extra lucky to have 240 hi leg delta serving my house and shop building.

[@hilineacademy8482]

Thanks. For the encouragement. Im thinking of buying a phase converter for my shop. Three phase equipment is nice. 👍

[@billyr9840]

I love watching and learning from your videos. Im not in the field but but i was always extremely interested in your type of work since a very young age. The way you explain how these setups work is extremely easily understood. Hope to see more videos in the future. Thanks !

[@hilineacademy8482]

Thankyou very much I appreciate the encouragement. I hope to have time this summer to do some more lessons.

[@chrisporter4170]

I’m just now learning this trade and your videos already make since to me! Need a couple hundred more please 😂

[@hilineacademy8482]

Lol. Thanks Chris. I’m on it. If you have any questions please ask. I’m all ears. Stay safe 👍

[@bobbyh6293]

Thank you for teaching me high voltage and understanding it better.

[@hilineacademy8482]

Any time 👍

[@AlistairBostrom]

Your videos are wonderful. Take a bow for a job well done!

[@hilineacademy8482]

Thank you sir. I appreciate it.

[@tommywatterson5276]

Great great explanation

[@claytonblomquist2378]

Nice video! First time vectors made sense to me!

[@hilineacademy8482]

That’s Awsome. Go check out the vector lesson. It gets better. Stay safe 👍

[@TechOne7671]

A well presented video with good explanations and example.

[@hilineacademy8482]

Thank you sir. 👍

[@LinemanUniverse]

Awesome video brother, great explanation👍

[@hilineacademy8482]

Thank you sir. I appreciate the encouragement. And right back at ya. Ive enjoyed your content for a long time too 👍

[@Sparky-ww5re]

Using distance was an easy way for my to visualize voltages between windings. In my neck of the woods 120/240V 3ø 4w delta systems are rare and where found are in old commercial and industrial buildings because in most cases a 120/208Y system is more appropriate. However I do see open delta 120/240V 3ø fairly often in rual areas, mostly on farms where the customer needs 120/240 1ø but also needs the ability to run light 3ø loads, such as a milker, augers/conveyers with motors of 7.5 HP or larger for example. I can spot these while driving down a country road by noting 2 transformers, a large and small pot,

[@hilineacademy8482]

Yes sir. I’m glad that you see the relation between voltage and distance. In my experience it’s the best way to understand where the voltages come from. Keep it up and if you have any questions drop me a line. Stay safe 👍

[@giacomotallarida4946]

Great job love the videos

[@hilineacademy8482]

Thankyou sir. 👍

[@davidjackson4112]

Thanks Cory.

[@hilineacademy8482]

No problem. Any time. 👍

[@nolanbrimhall1247]

This is awesome information! I am very interested in learning more about transformers. You make this subject very clear. Thanks for sharing your knowledge with us. We need more people like you in the industry.

[@hilineacademy8482]

Thanks Noland. I appreciate it. Stay safe. 👍

[@SolarElectricGuy-qw8sx]

nice and easy😀

[@hilineacademy8482]

👍

[@johnszott956]

I love all your videos, I love how thorough you are but explain it easily so everyone can understand. Was wondering if there maybe a workbook or downloadable files on some of the problems you go through in the near future?

[@hilineacademy8482]

Thank you. I don’t have anything downloadable right now. Maybe in the future. Keep learning and stay safe 👍feel free to ask any questions.

[@Smile-hp1xg]

Great video for sure learned something but we’re your case grounds lol

[@Bone_Apple_Tea]

Looking for more info or a video, if you could, on parallelling two different polarity banks. Any information would help out greatly! Thank you!

[@hilineacademy8482]

So could you give me some more info on your question? The scenario your talking about is very rare and I want to make sure I’m on the same page as you.

[@Bone_Apple_Tea]

Thanks for the reply. Let’s say two Closed Delta banks. One bank having subtractive transformers and the other bank having additive transformers. Being able to parallel the two banks so they phase in together

[@MinisterioElArtesano]

Why do you connect H2 to secondary neutro and says that is floats? Thanks

[@StoneStraiff]

Hero

[@hilineacademy8482]

Lol. Yup that’s me. 😅

[@kenneth7137]

Very interested to see what the differences would be on tying the delta vectors in different order

[@hilineacademy8482]

Lol. Yes sir. In class we call it the dream catcher connection. It’s a mess. In the industry there’s a few different names for the two different delta connections. Engineers would refer to them as standard and non standard delta connections. Funny enough the pretty one is called the non standard delta connection. You should draw it out. Stay safe 👍

[@kenneth7137]

@@hilineacademy8482 sure will thanks for all your informative videos

[@D.Hozzie]

Are guy’s actually doing vectors and such in the field? Just wondering? Great video!

[@hilineacademy8482]

Probably if they had a paralleling scenario that they were figuring out. But vectoring is a great way to learn about transformer hookups. It shows you the how and why in order to manipulate the hookups to get what we want. It’s an Awsome tool. Stay safe. 👍

[@wrestleorsurf]

Can you make a video explaining tapping up parallel runs in hand holes?

[@hilineacademy8482]

Maybe. I dont have the setup for that currently but maybe in the future. The best way to do that is to terminate the panel side first. Then using a continuity meter, identify the phases that are terminated together on the panel side at the transformer. Once identified, mark them with tape. Then terminate them at the transformer side being sure to use appropriate cover for the parallel run that comes hot while terminating. If you have any questions feel free to reach out. Stay safe 👍

[@PLEBEJones]

⚡️💪🏽👍🏽👌🏽

[@hilineacademy8482]

Thanks. Stay safe. 👍

[@jimdigriz3436]

As a licensed PE this guy knows his stuff but how is he working at ground level without full protection? Is this a training installation?

[@hilineacademy8482]

lol. I built a training simulator. The primary voltage is 120/208 3 phase. Hopefully here in the future I’ll do a video on how to build one for yourself. They’re not that complicated and it’s a lot cheaper to build one rather than buy one. Stay safe. 👍

[@linehandibew6205]

On our closed delta banks we float our neutral h2 bushings. They do not bond to system neutral. Why did t you flat your neutrals on your primary side. And can you give me insight on why we do it on our property. FYI system voltage is 7629/13.2 wye. Pots we use are conventional dual bushing pots 7620/13.2

[@hilineacademy8482]

Your correct. When we build closed wye-delta banks we are always supposed to float the primary neutral connection. I didn’t go through the process of floating it because I was trying to get the concept of using an open corner to make sure the connection is sound. The reason we float it is for several reasons and none of them are easy to explain in a text. The first reason we float it is so in the event of a phase that is feeding the bank goes down to the ground, it won’t be energized from being backfeed from the other two cans. The second reason is in the event of a power pot going bad, it won’t turn it into an open bank and burn up the other can or customer load. The third reason we float it is due to the impedance difference between the three transformers. With the neutral tied down, the transformers try to balance the impedance difference between the three transformers and it results to an added current on both the primary neutral tie and the ties between the transformers on the secondary side. This adds to an un accounted for current in the bank that lead to voltage imbalance on the secondary side. In other words, it’s just not as efficient. When we float the primary neutral connection it gets rid of the imbalance. Sorry it took so long to get back to you. Our apprenticeship classes just started up again and I’ve been running around like crazy. Stay safe and if you need any more help with anything feel free to reach out. 👍

[@linehandibew6205]

@@hilineacademy8482 thanks for getting back to me!!!! That’s what I was taught is it balances the three pots out. I’ve seen some utilities will use a cutout for the neutrals l. We just float them directly. I love transformer theory and learning more about them this way I can pass it down to my apprentices. I always tell them it’s one thing to know what connections to make and be a monkey plugging in wires. But to actually know why and how things work that makes a good knowledgeable lineman. Stay safe out there brother

[@eluv201]

@@hilineacademy8482🤙🏼

[@LNC4P]

Where do you get your primary input from? I mean, you don't usually get 4kv+ coming out of your wall and a residence usually doesn't get 3 phase. Do you create your own primary power in house?

[@hilineacademy8482]

Lol. I only have a regular 120/240 single phase service at my house. I had to build the three phase 120/208 source for the simulator. I bought a three phase converter which takes 240 single phase and makes 240 three phase. Then I had to build a conversion bank to go from 240 three phase delta to 120/208 three phase wye and that’s what feeds my simulator. So I actually do t have primary at my house. Lol. Stay safe. 👍

[@LNC4P]

@@hilineacademy8482 So, the transformer cans have been gutted of their step down transformers and replaced with isolation transformers?

[@hilineacademy8482]

@@LNC4P well they were 5 kva cans. 7200 pri input 120 volt sec output. I pulled the cores, stripped the windings and rewound them to have a 120 volt pri input and a 120/240 sec output. I still have to wind some 208 volt primary with various sec outputs. Haven’t had a ton of time. Life is crazy right now.

[@LNC4P]

@@hilineacademy8482 That's awesome. You should do a video explaining your setup. You should also explain why you're doing these videos and how you're able to gain all of your equipment.

[@hilineacademy8482]

@@LNC4P ya I hear ya. If nothing else, it would help some smaller apprenticeship programs with no budgets build a simulator for class. Having something real to measure makes all the difference in the world. Are you an apprenticeship instructor and if so where do you teach.

[@nickspatola8637]

Dont you float the h2 on a wye delta

[@hilineacademy8482]

Yes sir your right. On a closed wye delta bank you do float the primary neutral connection. In that lesson though I was trying to get the concept of using an open corner across and I forgot to float it. Lol. Stay safe. 👍

[@user-nn1lm6pm1g]

hello, I'm from Russia, I work at a substation myself, I would like to meet you

[@hilineacademy8482]

That would probably be hard. I don’t make it to Russia very often. Lol. Stay safe.

[@user-ye6dc8bk9x]

Can I buy a transformer cheat sheet book from u

[@hilineacademy8482]

Lol. I dont have any out yet. Hopefully in the future. 👍

[@samwestover9953]

my poll transformer reads 120/240 3 wire with a 200 amp service on the first building. A second building will have a 200 amp dual lug meter base that will feed a future third building with 200 amp service off the dual lug meter base on the second building, the second building with the dual lug meter base will have a service panel with less than 100 amps. what is needed on the poll for customer needs?

[@hilineacademy8482]

Are you asking what is needed in terms of transformer KVA?

[@user-nn1lm6pm1g]

you are on telegram?

[@hilineacademy8482]

No I only have youtube. I don’t have any other social media. If you ever have questions you can contact me on either youtube or my email.