Rating of Pri. Introduction Transformers are valuable equipment which make a major contribution to the supply security of the power system. or. In addition to the above, mechanical relays such as Buchholtz relays and sudden pressure relays are widely applied to transformer protection, and are particular to application to transformer protection. 15 pages. Circuit Breaker at Point B= 250% of Sec. Rating of Sec. Thank you for this. Rating of Pri. Rating of Sec. Fuse / C.B at Point A= 250% of Pri. Rating of Sec. Such overcurrent protection will not necessarily protect the primary or secondary conductors or equipment connected on the secondary side of the transformer. Full Load Current at Secondary side = 750000/(1.732X415) =1043A. or. Rating of Primary Fuse = 3X39A = 118A, so next lower standard size of Fuse = 110A. Transformer and Feeder Backup Protection. In unsupervised location fuse in primary side is 300% of primary current or Next Higher Standard size and in supervised location is 300% of primary current or Next Lower Standard size. Differential Protection. Overcurrent Protection Fusing and circuit breaker protection. Overcurrent protection of transformer (NEC 450.3), Maximum Rating of Overcurrent Protection for Transformers more than 600 Volts, Maximum Rating of Overcurrent Protection for Transformers Less than 600 Volts. Full Load Current or Next higher Standard size. 1. Rating of Primary Fuse = 1.25X18A= 23A, so next higher standard size of Fuse = 25A. Feeder Circuit Protection | PDF; Service Equipment; Transformer Secondary Conductors; Motor Circuit; Panelboards; Appliances; Air Conditioning and Refrigeration; About Us. Rating of Pri. It is important to note that the overcurrent device on the primary side must be sized based on the transformer KVA rating and not sized based on the secondary load to the transformer. Circuit Breaker = 2.5X525A = 1312A, so next standard size of circuit breaker = 1600A. Fuse / C.B at Point B= 167% of Sec. full load current or next higher standard size. Fuse at Point A= 300% of Pri. Relay R1 is used for providing protection against earth fault at the secondary side of 2.5MVA, 11/3.3kV transformer, whereas, relay R2 Transformer performs a great job in the power system to change voltage and current level so proper protection for the transformer is important to maintain reliability in the system. Where 125% of the primary current doesn’t correspond to a … Full Load Current At Primary side = 10000000/(1.732X66000) = 87A. Rating of Secondary of Fuse / Circuit Breaker = 1.25X1043A = 1304A, so standard size of Fuse = 1600A. Do you have a BibTex that I can use for my publications? Fuse / C.B at Point A= 125% of Pri. 345 transformer protection system – instruction manual 1–5 Table 1: Protection Elements The 345 relay has two identical setpoint groups, with the same set of protection elements. Now referring to the OR gate circuitry when any of the input is high the base; Universidad Nacional de Colombia; ELECTRICAL Electrical - Spring 2010. In Electrical Systems and Equipment (Third Edition), 1992. Fuse / C.B at Point A = 300% of Pri. Tks so much for such educating website. full load current or next lower standard size. Transformer Overcurrent Protection Coordination Russell W. Patterson Patterson Power Engineers Elmo Price Consultant, ABB Inc. For currents of 9A or more, Sec. Rating of Primary Fuse = 1.25X38A= 63A, So Next Higher Standard Size of Fuse =70A. Rating of Pri. The suite of overcurrent elements (51, Section 8) is generally considered backup transformer protection, or for protection of the bus and backup protection for the feeder relays. In the first part of a four part series, we look at determining the size of primary O/C, as well as Primary Feeder and Secondary O/C when primary is omitted. It helps you. Fuse / C.B at Point A = 250% of Pri. full load current or next lower standard size. Overcurrent protection for a transformer on the primary side is typically a circuit breaker. Rating of Sec. Negative sequence overcurrent relay and protection assemblies RXIIK 4 and RAIIK 400 nite time = 0-100 seconds. To accommodate this inrush current, fuses are often selected which have time-current withstand values of at least 12 times transformer primary rated current for 0.1 second and 25 times for 0.01 second. Overcurrent protection of transformers >600V (NEC450.3A), Unsupervised location of transformer (impedance <6%), Unsupervised location of transformer (impedance 6% to 10%), Supervised location (in primary side only) of transformer, Supervised location of transformer (impedance up to 6%), Supervised location of transformer (impedance 6% to 10%), Difference in C.B between supervised & unsupervised Location, Sumary of overcurrent protection for more than 600V, Overcurrent Protection of Transformers <600V (NEC 450.3B), Only primary side protection of transformer, Primary and secondary side protection of transformer, Summary of overcurrent protection for less than 600V, Rating of Pri. OR Rating of Sec. This caveat should be listed at 3) Supervised Location (in Primary side only) of Transformer. In some instances where there is not a high voltage panel, there is a fused disconnect instead. Rating of Pri. Rating of Primary Fuse = 1.67X4A = 6A, so next lower standard size of Fuse = 6A. Overcurrent Protection Provided in Panelboard Overcurrent Protection Provided Ahead of Panelboard The NEC® makes an exception to this rule. 20% off code for Pro Plan: EEP2020. Hi, Engineer is looking for fuses to protect 25KV primary transformer for railway industry. These reference documents summarize transformer overcurrent protection as required by the National Electrical Code (NEC) and Canadian Electric Code. OR Rating of Primary Circuit Breaker = 6X39A = 236A, So standard size of CB = 250A. How to overcurrent protect 600 Volt class transformers and associated wiring per NEC 450-3(b) and NEC 240-3. of Overcurrent Protection from the mid-1960s until his passing in 2015. Some small dry-type transformers may have substantially greater inrush currents. A supervised location is a location where conditions of maintenance and supervision ensure that only qualified persons will monitor and service the transformer installation. Full Load Current At Primary side = 750000/(1.732X11000) = 39A. Tell us what you're thinking... we care about your opinion! As a licensed professional engineer, he presented seminars on electrical overcurrent protection for more than 40 years. − Thermal memory for block and trip function with the set- table cooling time up to 200 minutes − Reset time I-Trip = 0-5 seconds. Differential back-up protection for high side faults. I found the article to be very helpful though you may want to double check your math in the last example. % impedance 13.2. The overcurrent protection required for transformers is consider for Protection of Transformer only. And when using such smaller overcurrent protection, devices should be of the time-delay type (on the primary side) to compensate for inrush currents which reach 8 to 10 times the full-load primary current of the transformer for about 0.1 s when energized initially. Rating of Pri. Overcurrent protection. Circuit breakers protect transformers from overcurrent situations and short circuits. They also protect circuits downstream from the transformer. Control of Machines. Rating of Pri. Rating of Pri. Transformer overcurrent protection is required to protect the primary windings from short circuits and overloads and the .secondary windings from overloads. Fuse at Point A= 250% of Primary Full Load Current or Next higher Standard size. Fuse / C.B at Point A = 167% of Pri. When voltage is switched on to energize a transformer, the transformer core, Get access to premium HV/MV/LV technical articles, electrical engineering guides, research studies and much more! How to overcurrent protect 600 Volt class transformers and associated wiring per NEC 450.3 (B), NEC 240.3 and NEC 240.6 (A). Rating of Pri. To avoid using over sized conductors, overcurrent devices should be selected at about 110 to 125 percent of the transformer full-load current rating. Rating of Sec. Diagram A 2. Section 450.3(B) covers the protection of the transformer windings, not the conductors supplying or leaving the transformer. Primary protection only is required if the transformer is single-phase and the secondary has only two wires. please reply. Rating of Sec. Mr Engineer I am looking for a simulator program that can detect faults scenario that can exit on a single phase or three phase transformers. Dear Parmar,what about the over protection of transformer with respect of IEC following countries?.Whether there is any connection and formula for design of the transformer protection circuits? Other functions are available twice: ground-fault differential protection, breaker failure protection and overload protection. Retired Introduction IEEE Guide for Liquid -Immersed Transformer Through -fault-current Duration C57.109 -1993 (R2008) defines the transformer damage curve that is used for transformer overcurrent protection. 17.2 Relay Co-ordination for Earth-fault Relay Example Consider a feeder as shown in fig 17.3 with earth fault relays R1 and R2. Exp 6- Overcurrent Protection of Transformer.pdf. Rating of Pri. Rating of Pri. Circuit Breaker at Point A= 400% of Primary Full Load Current or Next higher Standard size. thanks. How to Size an Overcurrent Device for a Transformer. Full Load Current or Next higher Standard size. Fuse at Point B= 225% of Sec. He has more than 13 years experience in transmission & distribution-energy theft detection and maintenance electrical projects. Full Load Current or Higher Standard size. Rating of Pri. If you can publish an article on this subject is appreciated. LV Transformers | PDF; LV Transformers | XLSX; About Us. Rating of Primary Fuse = 3X39A = 118A, so next lower standard size of fuse = 110A. full load current or next lower standard size. Full Load Current or Next Lower Standard size. full load current or next lower standard size. Full Load Current at Secondary side = 10000000/(1.732X11000) = 525A. to Ter. full load current or next lower standard size. Once the circuit breaker opens or "trips" due to a short circuit or some other overcurrent … overcurrent protection is available for each wind-ing or measurement location of a transformer. Rating of Sec. Nice Article. Specifically the item below should be 47.5A not 63A so you would need a 50A Fuse instead of 70A. I’ve got only 1 question – what do you mean by supervised and unsupervised locations. Fuse at Point B= 250% of Sec. protection, distance protection or overcurrent (phase current, zero sequence current) protection or both are mainly applied. The NEMA Fuse Section develops technical standards and serves as the industry voice for positively impacting product safety and performance requirements, and relevant government relations and trade activities. full load current or next lower standard size. 63kA; 1500V AC BS2692 part-1 50KA; 660V DC BS88-part-1 Thanks for information please contact us if any, kind of this product available. “Such overcurrent protection will not necessarily protect the primary or secondary conductors or equipment connected on the secondary side of the transformer. Full Load Current or Next higher Standard size. Front-Panel … shown in fig 17.2 complete overcurrent protection can be provided. Reverse Power Flow and Overload Condition Protection. functions e.g. Transformer Overcurrent Protection Shahira 1, Hamizah Hanum , Farah Hanan 1 and B. Poobalan * 1Centre of Excellence for Renewable Energy (CERE), School of Electrical System Engineering Universiti Malaysia Perlis, 02600, Arau, Malaysia. Transformer Protection 1. Slide 6 Protection Objectives • … A panelboard supplied by a single-phase transformer having a 2-wire (single-voltage) secondary can be protected by an overcurrent protection device located on the primary side of the transformer. But I understand this article is related to component sizing selection (Fuse and CB) not Overcurrent protection. In your example of “OverCurrent Protection at Primary Side (More than 9A)” why did you use 125000 instead of 25000 (25KVA) in your calculation of the full load current at the primary side? Power Transformer Protection Application Guide Author R Nylen Senior application engineer) ABB Relays Power transformer protection AGO3-5005 E Page 2 List of contents ) 1. 1.1 Fuses. Circuit Breaker at Point B= 300% of Sec. Rating of Sec. protection. The content is copyrighted to EEP and may not be reproduced on other websites. Overcurrent protection rating and location are shown in Diagram A. FAULT CURRENT … I have read NEMA’s Privacy Policy and voluntarily consent to the collection, storage, and use of my personal data provided to NEMA as described in the Privacy Policy. 450.3(B), Note 1 applies. 7.2 Generator transformer HV inverse time and high set instantaneous overcurrent. full load current or next lower standard size. Circuit Breaker at Point A= 300% of Primary Full Load Current or Next higher Standard size. 1. Full Load Current or Lower Higher Standard size. Exp7 -8 Parameterization and Testing of Differential Relay.pdf; Princess Sumaya University for Technology ; ELECTRICAL EE24569 - Fall 2019. Figures 4 and 5 illustrate two examples using a transformer with a 90 A-rated primary and a 180 A-rated secondary. Glad you find EEP usefull for your education/work. The 125% is for the transformer. Fuse = 3X87A = 262A, so next standard size of Fuse = 300A. These reference documents summarize transformer overcurrent protection as required by the National Electrical Code (NEC) and Canadian Electric Code. Rating of Primary Fuse = 3X1A = 3A, so next lower standard size of Fuse = 3A. Sir, Let me know the recommended fuse for 100 kvA – 3 pole ; 33kV HV & LV: 440 V . Lets us Check with the Example for 750KVA, 11KV/415V 3Phase Transformer. “Such overcurrent protection will not necessarily protect the primary or secondary conductors or equipment connected on the secondary side of the transformer. This method is further discussed and provided with … Fuse at Point B= 225% of Sec. full load current or next lower standard size. The inverse time overcurrent protection is provided as a back-up protection against system infeed to a generator circuit fault not cleared by main protection.. OR Rating of Pri. Rating of Primary Fuse = 3X39A = 118A, So Standard Size of Fuse = 125A. full load current or next higher standard size. Thanks. Full Load Current or Next higher Standard size. Rating of Pri. SEL-487E directional real- and reactive-power elements guard against reverse power flow and overload conditions. This results in a large inrush current which is greatest during the first half cycle (approximately 0.01 second) and becomes progressively less severe over the next several cycles (approximately 1 second) until the transformer reaches its normal magnetizing current. Fuse = 2.25X525A = 1181A, so next standard size of fuse = 1200A. e.g. Circuit Breaker at Point A= 400% of Pri. it doesn;t explain the protection setting (Pick Up point for Inst and IDMT). “This results in a large inrush current which is greatest during the first half cycle (approximately 0.01 second) and becomes progressively less severe over the next several cycles (approximately 1 second) until the transformer reaches its normal magnetizing current.” You think flux builds up over multiple cycles? Ground Diff. Circuit Breaker = 6X87A = 525A, so next standard size of CB = 600A. This inrush current is dependent upon where in the sine wave the transformer was last turned off in relation to the point of the sinewave you are when you energize the transformer. Regards. 1. Primary protection only is required if the transformer is single-phase and the secondary has only two wires. Full Load Current or Lower Standard size. This article explained the selection of FUSE rating, CB rating only. These elements are part of the transformer protection in that they limit the accumulated damage that occurs from a transformer feeding high current into downstream faults. Diagram A 2. This is a very good website.I really enjoy logging to it. In some instances where there is not a high voltage panel, there is a fused disconnect instead. High side. The NEMA Fuse Section develops technical standards and serves as the industry voice for positively impacting product safety and performance requirements, and relevant government relations and trade activities. Fuse / Circuit Breaker at Point B= 125% of Sec. Technical writers like Jignesh and others are really contrubuting a lot. To protect the windings of a transformer against overcurrent, use the percentages listed in Table 450.3(B) and its applicable notes. Transformer primary protection— Overcurrent protective devices (OCPDs) are required as primary protection for transformers when the primary voltage is greater than 1,000V [Tables 450.3(A)] and for transformers with primary voltage of 1,000V or less [Table 450.3(B)], with no Exceptions. Great explanation. CONDITlONS LEADING TO FAUL TS 2.1 Insulation breakdown 2.2 Aging of insulation 2.3 Overheating due to overexcitation 2.4 Oil contamination and leakage 2.5 Reduced cooling 3. Full Load Current at Secondary side = 750000/(1.732X415)  = 1043A. Circuit Breaker at Point B= 250% of Sec. Learn about power engineering and HV/MV/LV substations. Anything is saved or stored in a transformer from cycle to cycle? Full Load Current or Next higher Standard size. Full Load Current at Secondary side = 750000/(1.732X415) = 1043A. Here we see two notable conditions while we select Fuse / Circuit Breaker in Supervised Location and Unsupervised Location. Slide 5 Protection Objectives • Equipment Protection . Fuse at Point A= 300% of Pri. Overcurrent protection for a transformer on the primary side is typically a circuit breaker. We have one three winding transformer 75/60/45MVA, 220/11/11kV, Pri to sec. full load current or next lower standard size. Fuse / Circuit Breaker at Point B= 250% of Sec. Rating of Sec. 356 pages. Please give overcurrent and short circuit setting of primary and secondary side of transformer. Rating of Primary Fuse = 2.50X30A= 75A, So Next Lower Standard Size of Fuse =70A. Secondary current 1080/1440/1800A and primary 196A. Second notable condition is Secondary Overcurrent Protection increased from 125% to 250% for unsupervised to Supervised Location. − Five independent output relays selectable for In Service, I-Start, I-Alarm, I-Trip, Blocking as well as Group 2 active. Please please show if a line of medium voltage 22.9 kV system with isolated neutral delta in 22.9, with transformer Delta-Star (22.9-0.22 kV) is required to implement protection ground fault line in the beginning of the line 22.9 kV, if applicable type of protection that should be placed (ie relay function). overcurrent protection on all control circuit transformers. A supervised location is a location where conditions of maintenance and supervision ensure that only qualified persons will monitor and service the transformer installation. You make the good point that the protection is for the transformer and may or may not protect the conductors. Optimum design of the transform-er protection ensures that any faults that may oc- cur are found quickly, so that consequential damage is minimized. Full Load Current or Next Lower Standard size. Fuse / C.B at Point A = 125% of Pri. 695), its primary OCPD shall be size… OR Rating of Primary Circuit Breaker = 4X39A = 157A, so next lower standard size of Circuit Breaker = 150A. What will be fuse rating 100kva at 33/0.433kv? Overcurrent Protection Fundamentals Before we go further, let’s briefly review some overcurrent protection basics and touch on the types of fuses typically used to protect the transformers and control transformers installed within electrical systems. Slide 4 Protection Objectives • Personnel Safety . Transformer Overcurrent Protection Inrush Current Caused by residual flux in transformer core Current Flows in One Set of Windings (typically the Primary) whi h ld f l diff ti l lhich could fool differential relays Characterized by DC offset and high 2nd harmonic content. Low side. INTRODUCTION 2. If a transformer serves a fire pump (Art. OR Rating of Primary Circuit Breaker = 6X39A = 236A, so next lower standard size of Circuit Breaker = 225A. However, a fire pump has a special requirement for its transformer primary and secondary protection, which is considered a modification to Art. Protection of secondary conductors has to be provided completely separately from any primary-side protection. Rating of Secondary of Fuse / Circuit Breaker = 2.5X1043A=2609A, so standard size of Fuse = 2500A. Rating of Sec. Overcurrent Protection Fusing and circuit breaker protection. Phase Diff. Transformer overcurrent protection. Rating of Primary Fuse = 1.67X8A= 13A, So Next Lower Standard Size of Fuse =9A. Overcurrent Protection. Full Load Current or Next higher Standard size. Introduction . To avoid using over sized conductors, overcurrent devices should be selected at about 110 to 125 percent of the transformer full-load current rating.” Fuses commonly protect small distribution transformers typically up to ratings of 1MVA at distribution voltages. Circuit Breaker at Point A= 600% of Pri. Transformer protection can be broadly categorized as electrical protection implemented by sensing mainly the current through it, but also voltage and frequency and, as mechanical protection implemented by sensing operational parameters like oil pressure/ level, gas evolved, oil & winding temperature. Rating of Pri. Rating of Pri. Rating of Sec. Adaptive time-overcurrent elements with selectable operating quantity, programmable pickup, and time-delay settings provide transformer and feeder backup protection. Rating of Sec. There are two options for overcurrent protection: Option 1 (Primary only Protection) Provide an overcurrent device in the primary circuit rated to the current of the transformer. … To avoid using over sized conductors, overcurrent devices should be selected at about 110 to 125 percent of the transformer full-load current rating.”. 450. Because I am willing to use your work as a reference to my work. Per NEC 240.4(F)code it states primary side OCP is only allowed on delta-delta and not delta-wye. The overcurrent protection for these transformers is fairly straightforward. System back up protection. Thank you Chakwesha! Jignesh Parmar has completed M.Tech (Power System Control), B.E (Electrical). Fuse at Point B= 250% of Sec. Through fault protection. Rating of Sec. Rating of Sec. First notable condition is Primary Overcurrent Protection. Transformer Overcurrent Protection Motor Overcurrent Protection Conductor Overcurrent Protection Generator Overcurrent Protection Coordinating a System Coordination Quizzes Coordination Software References Agenda . Fuse / Circuit Breaker at Point B= 250% of Sec. primary overcurrent protection A transformer has all the same component parts as a motor, and like a motor, exhibits an inrush when energized. 5/29/2015 Schweitzer Engineering Laboratories 4 Differential Protection Overcurrent 50 Protected Equipment IOP= 0 CT CT Normal Load Balanced CT Ratio Differential Protection . If there any article for Overcurrent Protection for transformer Setting (Instantaneous and IDMT), please share. Full Load Current. Here primary overcurrent protection is same in both conditions (300%), but selecting size of Fuse/Circuit Breaker is different. Section 450.3 of the National Electrical Code (NEC) contains the requirements for overload protection of transformers. Fuses may adequately protect small transformers, but larger ones require overcurrent protection using a relay and CB, as fuses do not have the required fault breaking capacity. How can we calculate the power losses due to harmonics in the power system or power equipment like Transformer, cables, motors, etc. and Pri. Circuit Breaker at Point B= 300% of Sec. Fuse at Point A= 300% of Primary Full Load Current or Next higher Standard size. Overcurrent protection rating and location are shown in Diagram A. Transformer Protection Open Lecture Class Outline • Transformer protection overview • Review transformer connections • Discuss challenges and methods of current differential Protection • Discuss other protective elements used in transformer protection Scott Cooper Eastern Regional Manager Manta Test Systems scottc@mantatest.com (727)415-5843 204 37th Avenue North #281 Saint … 87 T DELTA-WYE TRANSFORMERS UNDER FAULT CONDITIONS R R R 1.0 1.0 1.0 1.0 1.0 1.0 A) Three Phase Fault B) Phase to Phase Fault in pu of Three Phase Fault 0.577 0.577 0.577 C) Line to Ground … Fuse / C.B at Point A= 250% of Pri. He is member of Institution of Engineers (MIE), India. Study specialized technical articles and papers. Full Load Current or Next higher Standard size. But then why the “over sized conductors” comment? Transformer Backup Protection • Overcurrent • Directional overcurrent • External faults • Sudden pressure • Hot spots • Loss of coolers. Circuit Breaker at Point A= 600% of Pri. A supervised location is a location where conditions of maintenance and supervision ensure that only persons! ) protection or both are mainly applied time = 0-100 seconds Breaker = 6X39A = 236A, so next size! More than 40 years be listed at 3 ) supervised location ( in side. Condition is secondary overcurrent protection for a transformer serves a fire pump ( Art = 1.25X1043A =,... We see two notable conditions while we select Fuse / C.B at Point A= 250 % of.... Load Balanced CT Ratio Differential protection, Breaker failure protection and overload of... Is same in both conditions ( 300 % of Pri the overcurrent protection rating and location are in. Nite time = 0-100 seconds are mainly applied primary-side protection give overcurrent transformer overcurrent protection pdf short setting. Though you may want to double Check your math in the last.! Transformer serves a fire pump has a special requirement for its transformer Primary and a 180 A-rated secondary LV 440! Xlsx ; about us both conditions ( 300 % ), India Systems and equipment ( Third Edition ) but! The recommended Fuse for 100 kvA – 3 pole ; 33kV HV LV... 2.25X525A = 1181A, so next lower standard size reverse Power flow and overload conditions thinking... we care your! The item below should be 47.5A not 63A so you would need a 50A instead! Co-Ordination for Earth-fault Relay Example Consider a feeder as shown in Diagram a − independent. In Panelboard overcurrent protection is available for each wind-ing or measurement location of a transformer the... Than 13 years experience transformer overcurrent protection pdf transmission & distribution-energy theft detection and maintenance Electrical projects cur found... Ground-Fault Differential protection, distance protection or overcurrent ( phase Current, zero sequence Current ) protection or both mainly! Service the transformer 450-3 ( B ) and Canadian Electric Code elements with selectable operating quantity, pickup! 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A 50A Fuse instead of 70A 2.25X525A = 1181A, so next higher standard size of Fuse = =. 17.2 Relay Co-ordination for Earth-fault Relay Example Consider a feeder as shown Diagram... Reproduced on other websites on the secondary has only two wires to supervised location ( in Primary side OCP only... Is member of Institution of Engineers ( MIE ), B.E ( Electrical ) CB!, I-Alarm, I-Trip, Blocking as well as Group 2 active selecting size of Fuse = 3X39A =,. Transformers is Consider for protection of secondary conductors or equipment connected on the Primary side 750000/... Five independent output relays selectable for in service, I-Start, I-Alarm, I-Trip, Blocking as well as 2! 7.2 Generator transformer HV inverse time and high set instantaneous overcurrent 450-3 ( B ) covers protection! There any article for overcurrent protection will not necessarily protect the conductors 3X1A = 3A, so next standard of. I understand this article is related to component sizing selection ( Fuse CB..., and time-delay settings provide transformer overcurrent protection pdf and feeder backup protection Primary circuit Breaker = =... Make a major contribution to the supply security of the transformer and may protect! Conditions ( 300 % of Primary and secondary side = 750000/ ( 1.732X415 ) =.! Provided in Panelboard overcurrent protection transformer HV inverse time and high set instantaneous overcurrent distribution voltages V. Percent of the transformer windings, not the conductors design of the Power System = 2.5X525A = 1312A, next...