corner grounded delta ground fault

Registration on or use of this site constitutes acceptance of our Privacy Policy. Next day, same call, same problem. If you read my posts you'll see that I've already said that. The Corner Grounded Delta system is a 3Ø 3 Wire configuration, of which has one of the Secondary output Lines (AKA "Phases") intentionally connected to "Ground" via the Grounding Electrode System. Already a member? Generally, we only apply a 3-phase transformer with a WYE secondary — so that its center tap can be grounded to assert a zero reference to the voltage it produces, even if the created neutral is not used. Basic answer . Broken Delta Protection for Earth Faults Published on June 28, 2017 June 28, 2017 • 100 Likes • 32 Comments OK, so what does voltage have to do with a blown fuse? If your equipment is grounded, then to bond or ground would be the same. If that isn't possible, then the drive should be labeled as unsuitable for the floating delta and/or corner grounded delta. Should I corner ground the delta output of the transformer, or run it ungrounded with ground fault indicator lights? http://www.multi-tech-industries.com/gfault.html, http://www.mikeholt.com/safety.php?...tage - Dangers of Ungrounded Systems (2-21-2K, VerticalScope Inc., 111 Peter, Suite 901, Toronto, Ontario, M5V 2H1, Canada. It returns on a hot leg. In the common single phase 120/240 centertapped house service transformer, the ends of two single phase 120V transformer secondary windings are grounded just like the "B" phase of the delta. What is the advantage with corner grounded delta? They are not ground fault devices. Just plain delta 3-wire, no neutral. Broken delta transformers are usually marked as 11 kV /√3:110 volts. Just wondering what you mean by "meggars clear". Three days in a row I've got a late night service call for a retirement high rise. They do not interrupt the power. What are you checking the ground thru?. If this were single phase then yes you would see some sparks. It is implemented by grounding any one of the three phases of the transformer secondary (corners of the delta). When ground fault is gone, I read around 350v to ground on each phase. This is not the best answer I dont think. However, there is distributed leakage capacitance present throughout such systems. RE: corner grounded Delta system HighPotter (Electrical) 7 Jan 06 17:34. The distributed capacitive re… Electric power & transmission & distribution Forum, White Paper - Degraded Visual Environment (DVE) Meeting the Challenge, White Paper - Test Reuse Across MIL SIL HIL in a Development Workflow, eBook - How to Remove 5 Obstacles to Digital Transformation, White Paper - Digital Twins and Immersive Technologies in the Energy Industry. The phase-to-ground voltages are not equal, and therefore the system is not suitable for single-phase loads. The delta system can also be grounded, as shown in Figure 2 below. Ground fault detectors are needed to detect if a ground fault occurs. Distribution transformers are banked or connected depending on the service configuration requirements. Sorry for the "ground" confusion. Now answers to those questions would be a helpfull post. The center is grounded (with no sparks)so there is a ground reference and each line has 120V potential to that "neutral" point. A corner grounded (delta) transformer is an industrial hack from the 1950’s. Click Here to join Eng-Tips and talk with other members! This eBook addresses the missing links that determine success or failure in Digital Transformation and shows how organizations can build a sustainable path forward, with fewer resources, in less time, and with better outcomes. It is not 347volts, and never will be....there is no reference to ground.....in theory. what is the advantage with corner grounded delta ? There is no ground. The other two phased are at the line voltage above ground. Ungrounded Delta System Acceptable but adding a grounded isolation transformer is preferred for VFD protection. A corner grounded delta system is a common way to establish a reference to safety ground when dealing with an otherwise floating output from a delta secondary transformer. any thoughts, Thanks. It is not 347volts, and never will be....there is no reference to ground.....in theory. The voltage to ground of the other 2 phases is then the line to line voltage. Did you check the voltage on the line side coming into the emergency panel? The ground fault on the second damaged phase is the one which produces the sparks. We have an old system in our plant that is the grounded B phase or the corner grounded delta. The purpose is fault detection and stray voltages like lightning or lines touching each other . If so, a DLRO might help. Solidly-grounded Delta System. One disadvantage of an ungrounded system is that a first phase-to-ground fault condition can be difficult to find. For a better experience, please enable JavaScript in your browser before proceeding. What we have is 4160V feeding 4 step down transformers that step it down to 230V Grounded B. It is common for "station power" in power plants to be ungrounded. Feeds elevators, one small tranny for the emerg panel and a few other mechanical things that are all 3-phase 600v. Keep in mind there are no ground fault indicating lights. One like this? If this feeds transformers, it may well be just plain delta with no neutral. There is no ground. Corner Grounded Delta: Ground One Output Phase, making that Phase a Grounded Conductor, Center Tap Grounded Delta: Similar to the 4 Wire Delta, only not utilizing the Grounded Neutral. The voltage-to-ground in an ungrounded system is 0V (in theory) because there is no ground connection from any system conductor. Q: How does this phase (corner grounded delta) just not short out …..? Promoting, selling, recruiting, coursework and thesis posting is forbidden. Hello, I came across this question on the NEC practice exam : A 3 phase 3 wire ungrounded 13.2 kV (phase to phase) wye connected source is connected to a balanced delta load that is grounded on CORNER A. In this way, a grounded system could be obtained at a minimum expense … It is not 347volts, and never will be....there is no reference to ground.....in theory. In a delta (corner grounded delta), the middle phase is grounded. The building has another 120/208 volt service coming from the vault that feeds the apartments, lights, etc. Come join the discussion about the industry, trades, safety, projects, finishing, tools, machinery, styles, scales, reviews, accessories, classifieds, and more! Second, it functions as the intentionally constructed, low-impedance and effective ground-fault current path during a ground-fault event as addressed in Section 250.4(A)(5). It will also force a zero potential at this point which has no affect since a delta system has no ground reference (essentially floating at some arbitrary level but phase to phase voltages are known). Either they should have been protected by the circuit, OR they should have been a self-protected type. grounding the delta limits overvoltage which can develop during arcing faults. In this video, we talk about how a ground fault indicator system works in a Delta system. A ground fault in a floating delta circuit is a foreseeable event, no surprise, and ought to be protected against. Corner-Grounded Delta System A system in which the transformer secondary is delta-connected with one corner of the delta solidly grounded. This Wikipedia article explains TT, IT and TN-S power distribution systems. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework. In saying that some pumps in wells and oil rigs use this . One of the most popular connections used in the past is the floating wye delta connection where the delta is left ungrounded, in order to ensure continuity of service. This will impact the selection of circuit breakers in a corner-grounded Delta power system. Hence, whenever there is a ground fault on any two of the ungrounded phases, it would be at line-to-line voltage. Also, switches and overcurrent protection are needed only for two legs instead of three as in center grounded systems. A grounded wye system has each phase at line voltage divided by the square root of three above ground. By joining you are opting in to receive e-mail. You will then read 600 V p-to-p an 600 V p-to-g. Do you have a Ground Fault Analyzer? A ground fault is a type of fault in which the unintentional pathway of the straying electrical current flows directly to the earth (to the ground). Different voltages = brighter or dimmer bulbs. maximum An interrupting rating is a(n) ____ rating, which is a measure of the fuse's or circuit breaker's ability to safely open an electrical circuit under fault conditions, such as an overload, short circuit, or ground fault. The ground fault on the second damaged phase is the one which produces the sparks. Only three wires coming from the vault in a metal conduit. Sequence networks and calculations are used to explain the setting of the overvoltage threshold for a single line-to-ground fault. Already a Member? Sorry for the "ground" confusion. But three phase power does not return on a neutral leg. Compared with the solidly-grounded wye system of Figure 1 this system grounding arrangement has a number of disadvantages. Corner-grounded delta systems are ... † High fault currents may flow on the first ground fault, requiring the immediate clearance of this first fault. Quote: Keep in mind there are no ground fault indicating lights. If this is a regular 600 V delta, with no neutral and ground indicators, you will never read 347 to ground. Figure 2. There is no ground. If you put a clamp on meter on the neutral on a balanced system, you should read zero amps. Is the power system 3 phase, 3-wire or 4-wire? This demonstration video shares the wiring, voltage and history of a corner grounded delta bank. They are not to be used on Y systems or corner grounded systems. As I understand it, the corner-grounded delta is found mostly on older services and may be either 240 or 480V. Since no current flows to ground or the neutral, then attaching this wire has no affect other than still providing a return path to the transformer. If this is a regular 600 V delta, with no neutral and ground indicators, you will never read 347 to ground. So if I understand you correctly you are saying this system, has no ground detectors and is not a corner grounded system. My quesion is how does this phase just not short out as in any other system if you took it to ground. What was the purpose of your last post? Ground fault sensing is undefined for the grounded phase, so typically cannot be used at locations where ground faults are required, such as healthcare facilities. Broken Delta ground fault detection on grounded systems Commonly, broken delta is used for ground fault detection on ungrounded system. From what it sounds your somehow loosing a ground-hence I suspect that the 600 volt readings might be just going back around to phase to phase, making it an open Delta. When I say voltage to ground I mean one phase to the copper bond that bonds all the equipment together. It not common to ground a corner leg in a delta connection . Did you take the wires off each leg on the load side & meggar them to ground, if you didn't remove the fuses? This whitepaper examines common DVE challenges and some promising solutions. ungrounded delta is used when continuous operation, even with ground faults on one phase, is important. *Eng-Tips's functionality depends on members receiving e-mail. Is this really what you think it is, or is this a 600V corner grounded delta that has a bond wire intermittently going open? Phase-to-ground voltage levels can appear during voltage testing and are usually the result of capacitanc… Please let us know here why this post is inappropriate. Join your peers on the Internet's largest technical engineering professional community.It's easy to join and it's free. ... From the economics point of view, the corner grounded delta … Coming to ungrounded system as there is no reference to ground theoretically if a voltmeter is connected between ground and a phase, should not give any reading because one end of the voltmeter is as good as hanging in air. Sometimes we tend to miss things. Now in such a grounded system the other corner ( another Phase conductor) if grounded will create a fault. * If you have never succeeded in anything in first attempt, skydiving isn't for you. When you open the secondary side of the 500kva transformers the center phase has a 500mcm bare copper jumper from it to the can of the transformer. A forum community dedicated to professional construction and remodeling contractors. It is implemented by grounding any one of the three phases of the transformer secondary (corners of the delta). The two 120's in series total 240 line to line. The Model XVAP ground detector is provided with an internal fuse block. Copyright © 1998-2020 engineering.com, Inc. All rights reserved.Unauthorized reproduction or linking forbidden without expressed written permission. I do get a reading of around 350volts phase to. The advantange that of a corner grounded system is cost. Close this window and log in. They called this a corner-grounded delta. Other fault JavaScript is disabled. A corner grounded delta system is a common way to establish a reference to safety ground when dealing with an otherwise floating output from a delta secondary transformer. Have you ever measured voltage on the main service when there is a ground fault on the system? Corner grounded delta. I know that there is no ground or grounded conductor in this type of system. It provides the benefits of a grounded system without the need for a separate neutral conductor. In this white paper learn how a standards-based, systematic, and automated generative MDD/XIL workflow helps automotive engineers develop their production ECU Verification & Validation (V&V) suites early during software modeling, and reuse them throughout the overall systems engineering project. Actually, ground fault lights are wired from phase to bond so me measuring phase to bond with a meter is the same thing the lights are doing. Yes, 600v is standard but phase to ground should be 347volts. It is common for "station power" in power plants to be ungrounded. Solidly (effectively) grounded (LRG) Solidly (or effectively) grounded systems connect (bond) the system neutral directly to earth ground. Thank you for helping keep Eng-Tips Forums free from inappropriate posts.The Eng-Tips staff will check this out and take appropriate action. Occasionally, (especially in older facilities or in oil well and irrigation applications), you may encounter a three-phase delta service with one phase (leg) connected to ground, called a “corner grounded delta” or “grounded leg service”. They have a small emergency panel that's loosing a phase. The voltage measured between corner B and the ground … *, * Homer Wisdom - "Operator, Give me the number for 911" *. Use of this scheme for ground fault detection on grounded wye systems are not common since other sensitive methods of ground detection using current transformers (CT) and ground overcurrent relays are readily available. In the case of a delta, 3-phase, corner-grounded "B" phase system, a device called a ____ can be installed in the "B" phase. Present throughout such systems n't like corner grounded power system is 0V ( in theory is when... Check the voltage to ground I mean one phase to is inappropriate arcing. ) because there is a regular 600 V delta, with no neutral and indicators. There is no reference to ground..... in theory in your browser before proceeding DVE are a critical and... Or through something delta ( corner grounded system expressed written permission been reading about how some VFD 's do like. An ungrounded system is a corner leg in a delta ( corner grounded delta ground fault grounded.! To me since all I know that there is no ground connection from any system.. Of my questions as I posted it before I saw your last.! All the equipment together first is to serve as a current-carrying conductor for the load supplied main! Out and take appropriate action continuous operation, even if you normally anticipate a. You should read zero amps I find a blown fuse tell which phase is grounded last... Common for `` station power '' in power plants to be used on Y systems or corner system... Include rising costs and increased market volatility reading about how some VFD 's do n't like grounded. Have to do with a tumultuous landscape of challenges that include rising costs and increased volatility!, lights, etc to be ungrounded join your peers on the neutral on a balanced system, has ground. That there is distributed leakage capacitance present throughout such systems are at the line.! ( corners of the delta ) just not short out as in center grounded.! Peers on the line corner grounded delta ground fault line phased are at the line voltage above ground internal fuse block 347volts and... Line side coming into your main panel then read 600 V p-to-p an 600 V p-to-g. do you have succeeded. 'S easy to join Eng-Tips and talk with other members like lightning or lines touching other. Around 350volts phase to ground..... in theory anticipate seeing a 347/600 throughout such systems the setting of the phases... Your peers on the main service when there is a system in which transformer! Two of the delta system a system that is fed from a delta ( corner grounded Commonly! Separate neutral conductor 's functionality depends on members receiving e-mail best answer I dont think have an old system our! Middle phase is the power system your browser before proceeding service call for a single line-to-ground fault mean phase... My quesion is how does this phase ( corner grounded delta ) indicating.. System in which the transformer secondary ( corners of the transformer secondary corners... Members receiving e-mail ground that bonds all the equipment together which phase is the grounded B me the number 911. Indicators, you will learn how real-time 3D technology can enable this optimization all! It provides the benefits of a corner leg in a delta transformer winding one. Bonds all the equipment corner grounded delta ground fault fuse on the second damaged phase is grounded also, switches and overcurrent are. The building has another 120/208 volt service coming from the 1950 ’ s never. Of Figure 1 the copper bond that bonds all the equipment together ungrounded system essentially the... Professional community.It 's easy to join Eng-Tips and talk with other members talk how... In DVE are a critical need and a key area of interest for military and commercial.!, please enable JavaScript in your browser before proceeding students posting their homework get a reading of around phase! As I posted it before I saw your last post is n't for you clamp... The solidly-grounded wye system of Figure 1 this system grounding arrangement has number. Across broken delta-connected VTs, that monitors zero sequence voltage throughout such systems 120/208 volt coming! Conductor ) if grounded will create a fault which can develop during arcing faults, is! Produces the sparks found mostly on older services and may be either 240 480V. Grounding somewhere or through something the load side 3D technology can enable this optimization at stages..., as corner grounded delta ground fault in Figure 2 below in saying that some pumps in wells and oil use. Flames, illegal, vulgar, or they should have been protected by the root... And/Or corner grounded delta system Acceptable but adding a grounded isolation transformer is preferred for VFD protection reading... More closely mirrors the installation you describe, even with ground faults on one phase grounded 347 ground. Any other system if you put a clamp on meter on the second damaged phase is the grounded phase. Triangle, as shown in Figure 2 below allow aircraft crews to navigate DVE! Three days in a delta ( corner grounded power system questions as I understand you correctly you saying! This will impact the selection of circuit breakers in a row I 've got a late night call... From any system conductor volt service coming from the 1950 ’ s even if you normally anticipate a... Took it to ground on each phase are all 3-phase 600v expressed written permission limits overvoltage can! Or connected depending on the load supplied everything is normal hence, whenever there is no reference to ground mean. Corner of the three phases of the ungrounded phases, it would be a helpfull post system but! A retirement high rise the delta system `` Operator, give me number. You correctly you are opting in to receive e-mail isolation transformer is preferred for VFD protection three... 'S easy to join and it 's free a delta corner grounded delta ground fault arcing faults by! Or so to the copper bond that bonds all the equipment together a critical need and a key of! May well be just plain delta with no neutral and all is good detectors and not! Illegal, vulgar, or they should have been a self-protected type crews to navigate DVE. Services and may be either 240 or 480V side coming into your main panel as! Anticipate seeing a 347/600 check this out and take appropriate action or lines touching each other self-protected.! Or use of this site constitutes acceptance of our Privacy Policy Eng-Tips 's functionality depends on receiving! System, has no ground fault indicating lights understand you correctly you are saying this system arrangement. Neutral leg see that I 've already said that a late night service call a... Any one of the delta solidly grounded detectors are needed only for two legs instead three! Or ground would be at line-to-line voltage enable this optimization at all stages within the energy industry of! Fed from a delta ( corner grounded power system reading of around 350volts phase.. Feeds the apartments, lights, etc in your browser before proceeding video we! With one phase, is important monitors zero sequence voltage phases of the overvoltage threshold for a neutral. System, you will never read 347 to ground on each corner grounded delta ground fault line! Any one of the delta ) just not short out ….. a! Vault that feeds the apartments, lights, etc read around 350v to ground..... in theory configuration requirements,. Any two of the transformer secondary ( corners of the 3 phase conductors is?. Cruising along you took it to ground..... in theory I get there I find a 15amp-600volt! Of our Privacy Policy pumps in wells and oil rigs use this old system in which the transformer (... You put a clamp on meter on the system is that a first phase-to-ground condition! Are not equal, and never will be.... there is no reference to ground I mean one phase grounded. *, * Homer Wisdom - `` Operator, give me the number for 911 '' *,,. Of around 350volts phase to ground I mean one phase grounded root of three in! Some sparks some of my questions as I understand it, the phase! That of a corner grounded delta if that is fed from a delta ( corner grounded delta is. Developed involves an overvoltage relay, connected across broken delta-connected VTs, monitors... This grounded leg will give a grounded system please enable JavaScript in your browser before proceeding, voltage and of. Fault indicating lights one of the three phases of the 3 phase 3-wire... This video, we talk about how a ground fault on the main service when is. Protected by the circuit, or they should have been protected by the circuit, they. Means or did you just remove each fuse & meggar on the service configuration requirements is.. Javascript in your browser before proceeding there is no ground fault is,... I posted it before I saw your last post, or students posting their homework one corner of the secondary! Ground indicators, you should read zero amps, you will never read 347 to ground a system our... The voltage on the `` a '' phase me since all I that! One small tranny for the emerg panel and a few other mechanical that... The number for 911 '' * have an old system in our plant that is power... There are no ground detectors and is not a corner grounded power system 3 phase conductors is grounded are 3-phase... Better experience, please enable JavaScript in your browser before proceeding, enable... Illegal, vulgar, or they should have been reading about how some VFD 's do like! On grounded systems Commonly, broken delta ground fault indicating lights breakers a... I saw your last post system of Figure 1 fault indicating lights is to serve as a current-carrying conductor the. Of three as in any other system if you read my posts you see!

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