Transformer primary and secondary OCPD, feeder sizing

Transformer primary and secondary OCPD, feeder sizing, Thread starter shortcircuit1; Start date Mar 20, 2020; 1; 2; Next, 1 of 2 Go to page, Go, Next Last, S, shortcircuit1 Senior Member, Location USA, Mar 20, 2020 #1 All, I am trying to confirm my calcs for transformers, See below 225kVA, 480 delta-208/120 wye Primary Amps=271A Based on 450,3b Primary OCPD=271*1,5=406A, I can …

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12,47kV Transformer Primary Feeder Sizing code question

The transformer is being fed by a fused switch with a 100E fuse, The conductors will run in conduit underground for +10 feet and then hop in a cable tray where they will run to the primary of the transformer, I noticed from 13,2kV Feeder Sizing that the primary conductor should be sized for the load of the transformer and future load growth, I

Hi
Does anyone make a #6awg 15kV cable? You might want to check your local cable suppliers, but the smallest size might be as large as #1, TherI figured someone would say that :
I almost added to my post that I would go with a #2 because that is the smallest stocked conductor by OkonitHowdy,
Do transformer feeder conductors not have to be rated 125% of the NP full-load current of the transformer they are supplying ie 112A @ 19Hey – I’m supposed to be asking the questions here Only joking of course,
I have not found anywhere in the Code that indicates a need to rateIn the Canadian Code it is under;
Section:- Installation of Equipment,
Sub Section:- Transformers
Rule 26-258:- Conductor size for transformeIn my opinion, the cable has to withstand the short-circuit presumed current,
For instance according to:
IEC 60076-5 Power transformers –Part 57anoter4 – Wow, a 316 MCM seems like overkill imho just based off of the installations I have seen in the field, But that doesn’t mean that the insAt first, I don’t think the fault clearing time of any CB could be less than 6 cycles[0,1 sec],
Second, for a supply cable, I think the fault cle7anoter4 – what CB are you referring to?
The primary conductors are protected by a 100E fuse, Clearing time at Isc say 26,5kA for a 100E per

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Sizing calculations for 20/3,3 kV, 12,5 MVA transformer

Typical calculations for a 20kV transformer feeder cable are presented below, After correct cable voltage classification the following considerations apply: Cable sizing for 20/3,3 kV, 12,5 MVA transformer feeder photo credit: cabletecservices,co,uk Current carrying capacity; Short circuit rating; Voltage drop; Earth loop impedance; Consider a 20/3,3 kV, 12,5 MVA transformer to be fed by

Power And Distribution Transformers Sizing Calculations

With the loss of one of the primary feeders and/or transformers, the main secondary breaker for that circuit can be opened and the tie breaker closed, allowing the one remaining primary feeder and transformer to energize all of the secondary bus, The service to one-half of the load is momentarily interrupted during this transition period,

NEC Guidelines for Transformer and Transformer Feeder

NEC Guidelines for Transformer and Transformer Feeder Protection, Sept, 16, 2015 When overcurrent protection is not required, Hua Yan, P,E,, RCDD, LC, CxA, Voice your opinion! This site requires you to register or login to post a comment, Email Address * Continue, No comments have been added yet, Want to start the conversation? Sign up for EC&M eNewsletters SIGN UP, Load More Content, https

Transformer Installation

Size Primary Conductor: Feeder conductors supplying continuous loads shall be sized no less than 125 percent of the continuous loads Sizing Equipment Grounding Conductor when required 250,122A: The size of the equipment grounding bonding conductor for the transformer primary is based on the primary protection device,

What size wire do I need to feed a 75 kVA transformer?

Continue Reading, Input cables and Output cables may be different, a 75-kilovolt-ampere kVA, three-phase transformer with an input voltage of 480V will be installed in a small industrial plant, This transformer is rated 75,000 VA 75 kVA × 1,000 = 75,000, The primary side current will be 90 amperes A 75,000 ÷ 480 ÷ 1,732 = 90,2 = 90,

Input cables and Output cables may be different a 75-kilovolt-ampere kVA, three-phase transformer with an input voltage of 480V will be installed4Hi, , , , Where does this question come from,, , Asked like that, you clearly do not understand the question,, , Asked like that, there is actually2Without knowing the configuration of the transformer single or 3 phase, delta or wye and primary voltage, the ‘correct answer’ cannot be determin1I consider it 3 phase transformer of 11000/415 volts transformer,Full load current inLT will be about 102Amp and 50 mm2 Aluminium cable will serve0I mean, that is the question we ask ourselves when first confronted with the problem at hand, The next question is knowing the voltage, The next qu0FOR 70 KVA transformer cable required, 70x 0,80 pf = 60 kw I = 60/1,7321/400/0,8=108 AMP for this load i recommande70 mm square 4 core xlpe/pvc/swa0There are some very good theoretical answers here, But I would like t explain practically why rating a transformer in kW will not be useful, By the129Praveen Upadhyay’s question: How do you wire up a 75 kVA transformer going from 480 to 208 including the grounds and neutrals and any bonding nee2You need to know the voltage and whether it is 3 phase or single phase, For single phase just divide the VA by the voltage ie: 10kVA = 10000VA so a34First of all, may I assume that you want to run a 2-pole 240V 100A feed?,, per the National Electrical Code NFPA70, that would require 1AWG cab5

Transformer Size Calculator

Transformer Size Calculator, When sizing a transformer, you need to know the kilovolt-amps KVA that your machine requires, This tool will allow you calculate the KVA that you need, This tool only evaluates common voltages for North America ie, 24v, 120v, 208v, 240v, 480v, and 600v, If you have a Eurpoean voltage or something else that is uncommon here then give us a call, Input Output

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primary feeder

Electrical Transformer Calculations

Primary Feeder; Length: ft Max Volt Drop: % Copper Aluminum 3#3Cu, 1#8Cu 1″ EMT 3#1Al, 1#6Cu 1 1/4″ EMT: Voltage Drop 13,84 V 4,99% Voltage Drop 13,78 V 4,97% Primary Config: Transformer Size: Secondary Config: Transformer Ground: 1#2CU 2 1/2″ EMT : Secondary Feeder; Length: ft Max Volt Drop: % Copper Aluminum 3#4/0Cu, 1#4/0Cu, 1#4Cu 2 1/2″ EMT 3#350Al, 1#350Al, 1#2Cu 2 …

Properly Sizing Grounds for Primary and Secondary sides of

Properly Sizing Grounds for Primary and Secondary sides of transformers, Hello all, I work as a distribution engineer at an electric cooperative, We are currently working towards re-doing all our overhead and underground specs for designing line, We are going through and updating the materials used to build these units for inventory control and are makeing sure we are up to code with our specs

Sizing Conductors, Part XXVI

Where the primary side conductors are feeder tap conductors and are not protected at the conductor’s ampacity, the transformer can be installed in accordance with the third tap rule, The tap rule in 240,21B3 pertains to taps supplying a transformer, but this tap rule is not just for the primary side conductors, Use this transformer tap rule when the total length of one primary plus one

Sizing Guide for Dry Type Transformers

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Sizing Guide for Dry Type Transformers Single Phase Transformers Primary Voltage Main Breaker kVA Rating Primary Lugs Secondary Lugs 208V 80A 15 100A 100A 208V 150A 25 250A 250A 208V 200A 37,5 250A 250A 208V 225A 50 400A 400A 240V 80A 15 100A 100A 240V 150A 25 250A 250A 240V 200A 37,5 250A 250A 240V 225A 50 400A 400A Three Phase Transformers Primary Voltage Main …

Transformer selection and sizing

Transformer sizing, The first step to sizing a transformer is to determine the load that will be served, either at the branch circuit, feeder or service level, This starts with estimating or calculating the demand load using NEC Article 220 and then applying and applicable demand factors, Based on the types of loads served, demand factors will reduce the calculated load to determine