The only loads are the pumps and a smaller transformer running heat and air, control and a light. Location Michigan Occupation Electrician Feb 24, 2023 #4 This is a 4 wire 3 phase delta high leg system. Be careful when installing slash-rated breakers on a solidly grounded high-leg delta system. 26(4) for conductor to be grounded. 102(C)(1) for sizing the grounded conductor. I recall the EE missed it, I didn't realize it (or. However, some utilities still provide this system, and many old installations still exist. There is no way of grounding a 480V system (or any over 260V L-L) to meet the 150V L-G standard. At the risk of repeating myself, I'll try to illustrate the difference with a few examples. Also note the one can use a slash rated breaker on a corner grounded 240 delta, it just has to be a 480/277 rated breaker. ¿Busca un manual de instalación rápida para el convertidor de frecuencia ACH580-01 de ABB? Descargue este documento en formato PDF y siga las instrucciones paso a paso para configurar el dispositivo y conectarlo a su sistema HVAC. I have multiple 240v single phase loads and (1) 240v 3 phase load. might occur when Phase A goes to ground on a 480V, B-phase, corner grounded delta system. If he has corner grounded delta then I could see misunderstanding ~500 volts to ground as a stinger leg - but there should be two legs that are ~500 volts to ground. 10656 posts · Joined 2007. The corner grounded delta (CGD) is one of the earliest forms of grounded systems in electrical installations. When you open the secondary side of the 500kva transformers the center phase has a. ALL 3 PHASE. The only equipment bonded together is the main panel board case to the cable tray. The two pole breakers can handle 240V or more to ground, as would be seen in a 416Y/240 system or a 240/480 three wire single phase or a corner grounded 240 delta, but not the 480V to ground seen in a corner grounded delta. NEC expert Mike Holt explains how to properly ground a corner grounded delta system and the special characteristics of these rare systems. Only for use with 480V Wye systems. Corner-grounded delta system. Every fuse and circuit breaker is assigned an interrupting rating. A high leg delta connection is a configuration in which one of the windings in a delta connected secondary of a transformer is centre-tapped and grounded. A 480 volt corner ground delta does not have any portion of the supply that operates below 277 volts to ground (aside from the grounded conductor itself) - you can not connect any load in a way that gives you less then 277 volts between conductors or ground on this sytem - a 277/480 rated breaker can not be used on this system. What exactly is an unbalanced delta system? Figure 3. 85). Perhaps it should be extended to cover the grounded conductor of a corner grounded delta with a 170% factor. Question, when connecting a Wye generator to the Corner Grounded Delta, will it work without any abnormalities. Voltage between phase A and C to ground would be 277v while Phase B to ground would be something like 347v (I'm just guessing on that number) This would all be on the primary side. Three single phase 480 transformers in a wye configuration. A corner grounded delta power system is a configuration where one of the phases (typically B phase) is solidly grounded. My recommendation on corner grounded delta is to bolt all three phases together and hire a monkey to throw the main switch! But seriously, you'll have nightmares with corner grounded delta, it causes wierd ground. These are obsolete methods but can still be found, mostly in older industrial areas. They are available. Not open for further replies. Along with the 'slash rating', Corner Grounded (grounded B phase) systems can impact the AIC ratings of breakers. For use on. It consists of a maximum current and the voltage at which the device is rated to interrupt the circuit. 1 of 2 Go to page. Class R fuses are rated for 100 kA, however without the rejection fuse clips - system is limited to 10 kA since Class H or K fused could be installed in the future. 240. You are now operating on a corner grounded delta unintentionally. My proposed fix is: 1). In a Delta system, you must either have one corner grounded, or you must have ground current monitoring if it is an ungrounded Delta system. They sent me back readings for phase-phase at 480V, but phase-ground measured approximately 277V for. Mr. It has (in this instance) 480v relative to the two other phases, and is 1/3 of the 3 phase circuit. 3 (f) This is applicable, only if it is a center tapped delta, 240/120 3P 4W. #1 · Feb 28, 2020. Der PE-Schutzleiter (GND) darf keinen Strom tragen! Der Neutralleiter N (Grounded Conductor) ist dabei als getrennter Leiter anzulegen und erst innerhalb der Verbraucherablage abzugreifen. optional based on the design of the electrical engineer. Master Electrician / Electrical Engineer. , a zero sequence voltage). If you do not ground one of the. Dies geschieht unabhängig von der Erdung der Stromquelle. According to mike holt one random? corner phase is to be grounded and bonded to the case of the transformer. Per NEC, not for use with ungrounded systems, impedance grounded systems or corner grounded systems (commonly known as Three Phase Three Wire Delta, Three Phase High Leg Delta and Three Phase Corner Grounded Delta systems). If it is a corner grounded delta, the grounded phase must be* grounded AT the transformer terminal, meaning you will be able to SEE the ground. Corner-grounded delta: One line conductor is grounded directly. PowerPacT B-Frame 15/20 A Thermal-Magnetic Trip. #1 · Feb 28, 2020. It could also prohibit a corner grounded 240V delta since using a grounding transformer a 240V system could be grounded with a L-G voltage of only 139V. ) 480 3ø, 3W Wye connected Impedance grounded system. NEC 430. If the leg chosen is the B phase, then the voltage to ground for A and C will be 240 volts, while for B it will be zero. On the primary side, what is the voltage to ground on each phase? If one is zero and the other two are 480 or 525 then yes it is a corner grounded system. And, without proper identification of the. Proper grounding reduces overvoltages, improves uptime, and isolates faults. Corner-Ground: The three corners of the delta arrangement are connected to the line conductors. You will read 480v from l1 and l2 to ground, 0 v on the neutral leg to ground. Listed means one follow the instructions. ® (UL®) Listed products for this application. Corner-Grounded Delta Circuits. Phase readings as follows: A to…By grounding a corner of the delta, you help stabilize the phase to ground voltages and the phase to phase voltages will also be stable. #20. As detailed above, a delta secondary Transformer cannot have a neutral, while a center-tapped delta secondary Transformer, once the center-tap is bonded to the nearest earth ground per the NEC by the installer, can have a limited. By "fail", it would have to mean a GROUND FAULT. When I look at the bank on the pole I see 2 primary and 1 primary neutral conductors and 2 transformers. Therefore, it is not correct to refer to all grounded conductors as neutral conductors, although that is the case in the majority of electrical distribution systems. Louis. NEC 240. Check Details. If one phase is zero volts to ground, you probably have a corner grounded delta. Small residential is normally single phase 2 wire or single phase 3 wire. Schneider Electric has tested equipment for use on corner-grounded delta systems to provide Underwriters Laboratories Inc. One certainly would not corner ground a primary delta. It would seem to me, that there is no difference in principle between the grounded conductor in a 3 phase, 4 wire delta system, the grounded conductor in a 3 phase, 4 wire Y system, or the grounded conductor of of a 3 wire 240/120 volt system, or the grounded corner of a delta system as being disscussed. ChrisSeems like a trick question. To obtain UL certification, the TVSS unit must pass all tests. 85. Just speculation: Probably not really a neutral, but they likely had one leg of the delta winding grounded (corner grounded delta) because if not, they would have needed to add ground fault monitoring to that circuit, and at 4160V, that would have been expensive. 99 votes, 37 comments. corner grounded delta systems, considers the circuit breakers’ individual pole interrupting capability. Corner grounded delta systems are very common here, we have them with 220V and 440V, but 440V is rather seldom. Industrial mostly, and irrigation pumps. Corner grounded delta systems produce crazy voltages, and crazy ground faults. High Leg Delta Transformer Connectionmight occur when Phase A goes to ground on a 480V, B-phase, corner grounded delta system. I would call the 4rth wire a ground wire unless it was used for load unbalance. Neutral Conductor. That’s why you get 0volts from it to ground because it’s at the same potential. That 'neutral' is of course not a neutral, but a parallel 'grounded phase' conductor. We have addressed neutral loads using individual 480V x 480/277V. #5. The grounded conductor is treated like a neutral in 120 V and 240 V single-phase systems. The correct solution is to use a 208 Delta X 480Y xformer. I would normally only use a solid corner ground on a. The Article 100 definition for neutral was added in the 2008 NEC. That corner grounded delta system still needs equipment grounding conductors run beyond the service disconnecting means, you do not bond any equipment to the current carrying B phase at equipment you run separate EGC like you do for other voltage systems. A circuit breaker with a special “straight” rating of 277/480 volts may be used on a corner-grounded delta system. 2 requires a grounded conductor in all premises wiring. Pole pigs are 2 winding transformers with each winding isolated from one another. 480 x 1. Indication Contacts. primary. 20(A). D1-D4 lumen packages only. The only time you will see delta B corner grounded is when original older system was ungrounded and it was modified to be grounded by taking B phase and intentionally grounding it. It is both, ground and hot. We have an old system in our plant that is the grounded B phase or the corner grounded delta. MRG, Article 200. Location North of the 65 parallel Occupation EE (Field - as little design as possible)Most 480 volt delta systems are corner grounded by the utility and a 4th ground wire is brought to the service. 36 requires where fuses are used for motor overload protection that a fuse be also inserted in the grounded conductor if the supply system is a corner-grounded delta system. Measured voltage on tenant panel 480 A-B, A-C, B-C. A straight rated CB (such as 480V) can be applied on systems that have no more than 480V between any two conductors. 3 phase 480 corner grounded delta. Another indicator is you say your VFD’s run fine, the vast majority of VFD’s have MOV surge. A phase 490-ground B phase 490-ground C phase 0. Along with the 'slash rating', Corner Grounded (grounded B phase) systems can impact the AIC ratings of breakers. As far as marking, I have never seen a corner grounded system where the grounded conductor was identified as required by the rules in 200. Figure 2. Another disadvantage, as given on page 33 of IEEE. A 480v delta with a coil center taped for a grounded conductor (neutral) would be considered a 277/480 high leg. NEC 430. No, it is not showing the high side delta winding is corner grounded. Location UK Occupation Retired Electrical EngineerThe loads don’t know the difference. Could be the outlet is miswired or mis-breakered and has two of one line and one of a second. A phase is connected to each corner of the delta. Power company recently replaced transformers and now that businesses are opening back up. I have seen corner grounded deltas for 3 phase motors, but my situation is a bit different. Terms in this set (83) In the case of a delta, 3 phase, corner grounded "B" phase system, a device called a ___ can be installed in the "B" phase. The CB panel fed by the transformer secondary (240/120V) has a grounding electrode where the secondary center tap (neutral) is connected but as stated the corner grounded delta supply is not connected to it. APPLICATION ON GROUNDED . The grounded conductor is defined in Article 100 in the National Electrical Code (NEC), but this definition can cause confusion when it’s used in an electrical system. Aquavar CPC For R4 or N4 frame size, remove EM3. Usually different on each phase. Sounds to me like it’s a corner grounded delta with no 120V tap. Question, when connecting a Wye generator to the Corner Grounded Delta, will. 85 Applications. Image used courtesy of Lorenzo Mari . 23(A)(2) show instances. grounded TN systems (TN-S systems) 1 Corner-grounded and midpoint-grounded delta systems 2 (< 600 V) IT systems (ungrounded or high-resistance-grounded [>30 ohms]) 3 R10, R11 Do not remove EMC AC or VAR. Whichever you want to call it. One of the phases, normally A phase, is connected to a grounding electrode. Jun 21, 2023. (2) In ungrounded systems, impedance grounded systems, or corner-grounded delta systems unless listed specifically for use on these systems. I got a call today from dry cleaners he wants to add new washer. The size of the step-down transformer is. There are multi-tap ballast units, which can be 480V, 240V, or 208V, in addition to 277V, all of which are Line-to-Line connections. hello. Circuit Breakers for Grounded B-Phase (BØ) (Corner-Grounded Delta) Systems. This Wikipedia article explains TT, IT and TN-S power distribution systems. 240V. There is of course the resistance-grounded wye, if needed, for industrial. You're describing "high leg" or "wild leg" delta. 73) - Upon ground fault, the faulted phase L-G reading is zero and the other two. K. 24(D)(4) This section covers impedance grounded services. One method of grounding a three-phase, three-wire, delta-connected system is to ground one of the phase conductors. Schneider Electric has tested equipment for use on corner-grounded delta systems to provide Underwriters Laboratories Inc. Thread starter William Robertson; Start date Jan 21, 2021; Status Not open for further replies. Schneider Electric has tested equipment for use on corner-grounded delta systems to provide Underwriters Laboratories Inc. I can see 1 phase of the secondary is grounded to the common primary neutral. Figure 4 – Fault to Ground on a Corner-Grounded Delta System A disadvantage of Corner-Grounded Delta systems is the inability to readily supply voltage levels for fluorescent or HID lighting (277V). Aside from serving the step-down transformer, the 480V side is mostly going unused. 5% each you coould. Frame size EMC filter (+E200) screw Ground-to-phase varistor screw R10, R11 EMC AC VAR Drive. Whichever you want to call it. Agreed, corner grounded delta, but strange that they have two separate conductors for 'grounded phase conductor' and 'neutral conductor'. Z. Grounding center of one side (high leg 240/480 delta) might still be too high a voltage. 1) The neutral system has lower line-ground voltages 2) In a corner grounded HRG system, detecting ground faults in the grounded circuit conductor would be more difficult. A two-pole circuit breaker applied on a 3-phase. ) Only standard ampere rated fuses and circuit breakers found in 240. 2, September 2021 - updated list of supported inverters . True. This wire must be white or grey, because it is a grounded conductor, even though it isn’t a neutral. Feb 3, 2009. I wasn't sure what issues it might cause having one of the phases to ground be 0 volts. Slash marked circuit breakers such as 120/240V or 277/480V must not be used. IN reference to. Besoeker3 Senior Member. g. MRG, Article 200. While the rail-rail DC component of the rectifier output is the same in both wye and corner. Only for use with 480V Wye systems. - All phase L-L voltages are normal and the same. This system exists to keep voltages stable, limit or reduce surges, and/or be. The system has accidentally become a corner-grounded delta system with little, if any, current flow. The grounded leg is no more dangerous than the grounded neutral leg in a 120 volt circuit. Red leg 240 delta four wire was also a standard system and if that was floating (or maybe even grounded at the pole) you would get 120, 120, 183, *or* 0, 240, 240 if A was faulted without being noticed. You are correct in that a corner grounded delta would have 240V L-L x3, the corner would have 0V to ground. No 120/240VAC circuit breakers may be used on any corner grounded delta system. OccupationHey this happens all the time. 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”. (Read the same voltage measured to Ground)Corner grounded delta systems have a grounded conductor but it is not a neutral conductor. Sections 503. . LHL361005861). Circuit breakers marked “1-phase – 3-phase” or “10I – 30I “are suitable for use on are removed. Two phase-ground voltages = 480V and one phase-ground. The minimum size of the grounded conductor for a 3-phase, 3-wire, corner-grounded, delta connected service is a. Lexington KY. This is a "Corner Grounded Delta" system and is found in older facilities that have no need for 277 volt service such as a manufacturing facility or a central plant in an apartment complex. Aside from serving the step-down transformer, the 480V side is mostly going unused. (3) If the voltage rating of the SPD is less than the maximum continuous phase-to-ground voltage available at the point of connection. Remember that all the rules in the NEC that apply to grounded conductors are applicable to a grounded phase conductor in this case as well. 85 permits one pole of a motor controller to be placed in a permanently grounded conductor provided the controller is designed for all conductors. Another variation is a "corner grounded" delta system, which is a closed delta that is. Delta system. In einem Delta – System werden alle angeschlossenen Komponenten direkt geerdet. #4 · Oct 2, 2020. If you do ground one leg, you will only get zero on that one leg. Typically in my area BOY is used for any 480 volt power and if a grounded conductor involved, it is grey or marked grey. Same with "wild leg" center grounded delta, which is also becoming obsolete. #3. 85 covers the requirements for straight rated and slash rated CBs. 73 =830v; I don’t think it’s a wye system, could just be an oddball system. Occasionally you may have an application that is a delta voltage source with a grounded “B” phase, also known as corner grounded. However, some utilities still provide this system, and many old installations still exist. Since one phase is already grounded this 4th wire is somewhat redundant. The earth. looking for advice on working on a 3 ph, 3 wire 480 delta that i believe fits the definition of a corner grounded delta. b. 67 to 1. Also don't forget that NEC doesn't apply on the utility side of the interconnection point. And Delta ground monitor. The service company sent us a Magnum Power Genset (by Generac). Directions Advertisement. Jul 4, 2023. NEC Article 100 defines interrupting rating as “The highest current at rated voltage that a device is intended to interrupt under standard test conditions. Figure 4 – Fault to Ground on a Corner-Grounded Delta System A disadvantage of Corner-Grounded Delta systems is the inability to readily supply voltage levels for fluorescent or HID lighting (277V). Location NW Florida Occupation Electrical Jul 20, 2023 #8 Phase to neutral are 124, 214, 124. The delta system is grounded through parasitic capacitance from each phase to ground. Location. Our instructor made a point to warn of corner grounded Delta transformers, since you get your "phase-to-phase" voltage present "phase-to-ground". on corner grounded delta when using Class J or R fuses. This can be avoided by simply checking more than one leg, but the plain fact is that the customer doesn't like corner-grounded delta, and doesn't want it used. g. Re: Ground Fault Protection in Corner Grounded Delta System. They are available. If the leg chosen is the B phase, then the voltage to ground for A and C will be 240 volts, while for B it will be zero. 12. ® (UL®) Listed products for this application. Fig. I wasn't sure what issues it might cause having one of the phases to ground be 0 volts. Introduction Grounded systems offer many benefits over ungrounded systems [1][2][3]. A corner-grounded delta transformer connection is an example of a system permitted to be grounded. I pointed out that in industry it is quite common for an ungrounded delta secondary to allow continuous ops while the partial/total phase grnd. False Note: “Straight” rated circuit breakers are rated at 240, 480, or 600 volts and not 277/480 volts; which is a slash rating: Interrupting ratings on AC rated circuit breakers are used for ? . not smaller than the size of the grounding electrode. Marking on 3 phase matters especially with corner grounded delta as this sets up a wild leg that is required to be marked B leg and identified with orange phase tape the phases are 120 degrees out of phase so it matters how they are connected. If you had a corner grounded delta, B phase grounded and A phase shorts assuming you protected everything per the NEC you would have a ground fault and the fuses would blow or the CB open. "C" phase is solidly bonded to ground. Three pole breakers are allowed, because you are opening all three phases at once. Solidly-Grounded wye or star configuration : Yes: High resistance grounded wye or star configuration : No: Ungrounded wye or star configuration : Asymmetrical: Grounded at the corner of the delta connection : Grounded at the middle of the side : Single-phase, grounded at the end point : Three-phase variable transformer without. 408. I figured at the least it would cause a phase loss alarm, but wasn't sure if there was. There was never a GEC installed to the water ground or to. High leg delta has one winding center tapped. Where a delta-fed system must be grounded for detection of stray current to ground or protection from surge voltages, a grounding transformer (usually a zigzag transformer) may be connected to allow ground fault currents to return from any phase to ground. 24, 250. ® (UL®) Listed products for this application. Figure 11. Do not remove EMC AC or VAR. teal854t Discussion starter · Oct 13, 2010. . Pretty curious though. Not open for further replies. Corner Grounded Delta Solidly (effectively) grounded (LRG) Solidly (or effectively) grounded systems connect (bond) the system neutral directly to earth ground. Not sure why you would see a voltage increase if you lost a primary phase, though. Corner grounded delta bank is three wire, grounded delta. ® (UL®) Listed products for this application. The delta system has a phase-to-phase voltage of 240 V. However, some utilities still provide this system, and many old installations still exist. Grounded Systems Ltd. For example, the grounded conductor, as previously defined, could be a corner-grounded phase conductor per 250. When connected to the no. If an electrical system is grounded as a requirement or by choice, all the rules related to grounded systems must be applied. Remove EMC AC, VAR. Sounds like you know you have three supply conductors but don't exactly know what they are. Other types of three-phase supplies are wye connections, ungrounded delta connections, or corner-grounded delta ("ghost" leg configuration) connections. I would think if at a school there would be a system with 120 volts somewhere and not just corner ground delta everywhere. The ratings on the gen set are for 1 ph, 190 kVA - 240V 3 ph, 237 kVA 0. 3830 posts · Joined 2010. The grounded neutral conductors typically carry the maximum. 1) The neutral system has lower line-ground voltages 2) In a corner grounded HRG system, detecting ground faults in the grounded circuit conductor would be more difficult. Until the service is restored we need to get power to the facility. Basic cheap plug-in breakers are “slash” rated, meaning 240/120V; they are rated 240V phase to phase, but 120V phase to ground. A-B: 240V. The solidly-grounded wye secondary is the modern way to go for 600V. Corner grounded delta. The NEC® addresses slash voltage ratings for circuit breakers in 240. Indication Contacts. 2778 posts · Joined 2014. Use of a slash rated breaker on a corner grounded delta is not ruled out by it not being solidly grounded but by the voltage to ground on the two ungrounded wires being greater than the second number in the rating. Perhaps it should be extended to cover the grounded conductor of a corner grounded delta with a 170% factor. Aside from the corner-grounding of the delta, this is a fairly common configuration for transmission substation transformer in the US. Another disadvantage, as given on page 33 of IEEE Std 142. But, what I could do is put an auto-transformer between center of one side and the opposite corner. 2 requires a grounded conductor in all premises wiring. Figure 2 – Corner-Grounded Delta System arrangement and voltage relationships. 3. Corner grounded Delta (One phase conductor is connected to the grounding electrode system. It is a 240v CGD. Its corner ground Delta 3 phase , 208 V , 30 horsepower. 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. 90(B). Corner-grounded systems were used to supply services serving only a 3-phase load such as a well pump. High leg delta has the mid point of one side. If such systems are grounded, they shall comply with the applicable provisions of this article. Claim this business (250) 884-1942. 240V. The inverters may not like the elevated voltages to ground. it is three phase 240 volt the panel is 200 amp three phase corner grounded the listing in the panel 120/240 volt single phase or 240 volt three phase delta. Could be as jraef mentioned. 73) - Upon ground fault, the faulted phase L-G reading is zero and the other two. There is no way of grounding a 480V system (or any over 260V L-L) to meet the 150V L-G standard. 02. 85, which requires a circuit breaker. This panel runs a 20 ton air handler. Why would a corner grounded Delta system have a 4 wire drop? SDG&E?s Service Standards book states: ? On overhead service installations the service ground conductor, provided as the redundant 4th wire corner ground conductor of a 480 volt delta service, will be connected to the customer?s identified equipment grounding conductor at. Corner Grounded Delta. I have a job where they want to install a Dan Foss FC202 on a pump. B-Grd: 0V (assuming B ph is the grounded phase) C-Grd: 240V. It kind of freaks me out measuring 0 volts to ground on a open buss 4-5 thousand amps switchgear in the powerplant. 480V – 3-Phase, 2-Wire – Corner Grounded – Delta. Corner grounded Delta transformer systems are known to confuse people. A grounded conductor is to be pulled in with 500 kcmil THHN/THWN aluminum conductors as parts of a 277/480 volt 3phase 4w servioce to a 300 amp fused safety switch. In a 480V, three-phase, 3-wire delta system, the voltage-to-ground is always 480V whether it is ungrounded or corner-grounded. See data bulletin 2700DB0202. See Figure 11. Phase ab 240v, ac 240v, bc 240v, a to ground 120v, b to ground 0v, c to ground 120v. Occupation. . A two-pole circuit breaker shall not be used for protecting a 3-phase, corner-grounded delta circuit unless the circuit breaker is marked 1φ–3φ to indicate such suitability. You still must run a separate grounding conductor to bond non current carrying components - so you are running 4 wire circuits either way you do it. 8. ® (UL®) Listed products for this application. Commercial buildings require 3P4W and ground. On a 240V 3 phase grounded delta system, the voltage to ground is 240V from 2 of the poles. i agree. Corner-Grounded Delta (Grounded B Phase) Systems 2700DB0202R2/09 Data Bulletin 02/2009. Three-phase — 4-wire 120/240 volt delta connected system (high-leg). Doing this is technically challenging and expensive, however, the corner-grounded system offers. He said that it's about 240 volts so 128 volts to ground isn't that far off for a corner grounded Delta. BTW, this is a grounded system. a delta winding, with the corner ground not causing any difference to actual operation unless the higher voltage from tap to ground is a specification issue, or. 480V. If you built the system using say a corner grounded delta (say B phase grounded) then you would see high current from A to B and from C to B but I suspect. larz_6446 • 2 yr. This is a delta - delta transformer. At the transformer, the grounding electrode conductor, grounded phase, and equipment grounding conductor all tie together. You have a different problem. #2 · May 30, 2022 (Edited) If the system is to be a 208 or 480 grounded B and you have only 120 or 277 transformers, the corner grounded Y will work. If that isn't possible, then the drive should be labeled as unsuitable for the floating delta and/or corner grounded delta. 600 Y/347 V, 3. 242. They have 3 phase delta 480. Ampere rating of fuse or circuit breaker not to exceed switch ampere rating. 250. The easiest way to ground a delta is at a corner, which also happens to be convenient in converting/upgrading ungrounded systems. I hooked up 240v 3 phase motor to make sure and. 12,470/7200 grounded Wye primary and. L-N: 277V L-L: 480V 480V. C orner-grounded delta grids are not supported at these voltages. Reply. We own the transformer. A circuit breaker with a slash rating, such as 120/240 V or 480Y/277 V, may only be installed in a circuit where the nominal voltage of any conductor to ground does not. 'power' panels (e. I hooked up 240v 3 phase motor to make sure and. . I am in north Texas, where usually when I see a corner-grounded delta, it is really a pretty old ungrounded delta that has a ground fault or multiple faults on the same leg. A. The MOV surge protectors in your drives will not like one or two legs of a higher voltage to ground. 120/240 V, single-phase, 3 W, solidly grounded III. For use on 240 V systems, circuit breakers may be ordered as 480 V. 24(C) Grounded Conductor Brought to Service Equipment and immediately below in (C)(1) is a reference to 250. For example, a 480 V, 3-phase, corner-grounded, delta-connected system cannot use a 480Y/277 V circuit breaker because the voltage of two phases to the ground exceeds 277 V. This is an important marking to note as we. This is coming from the corner grounded delta that is feeding the buss. Yeah a 3 pole on a corner ground delta system feeding 3ph equip. Scanning through 250.