what happen if measuring ct is used as protection ct

1

Answer by Littlewats This can be done, but is usually not done because a metering CT is made to be very accurate at expected load current levels. A protection CT is made to be accurate at fault current levels (which is often significantly above load current). If the CT is too small, and has too small of a ratio, the CT will likely saturate, which will skew the results the protective device expects to get. An example: a metering CT may have a ratio of 100:5 (made for 100A load current, which will produce 5 amps secondary current). Fault current levels may be ~10,000A. You'd expect the secondary output of a perfectly linear CT to be 500A. One way resistance of the cable connecting the protective device to the CT may be on the order of .5 2 ohms. Ignoring the resistance of the CT and connected devices, secondary voltages would reach 250 1,000 volts for a phase fault, and 500 2,000 volts for a ground fault. The biggest CTs may be rated for 800 volts output below the knee point, so this 100:5 CT would clearly saturate. The real output current would likely be on the order of 150A at the most. ...And the above is ignoring any DC offset, which would cause the CT to saturate at unpredictable AC current levels. EDIT 5.2K CONFIDENCE VOTES What happen if measuring ct is used as protection ct?

Upload: catalincc

Post on 08-Nov-2015

4 views

Category:

Documents

0 download

Report

Download

Embed Size (px):

DESCRIPTION

CT

TRANSCRIPT

AnswerbyLittlewats

Thiscanbedone,butisusuallynotdonebecauseameteringCTismadetobeveryaccurateatexpectedloadcurrentlevels.AprotectionCTismadetobeaccurateatfaultcurrentlevels(whichisoftensignificantlyaboveloadcurrent).IftheCTistoosmall,andhastoosmallofaratio,theCTwilllikelysaturate,whichwillskewtheresultstheprotectivedeviceexpectstoget.

Anexample:ameteringCTmayhavearatioof100:5(madefor100Aloadcurrent,whichwillproduce5ampssecondarycurrent).Faultcurrentlevelsmaybe~10,000A.You'dexpectthesecondaryoutputofaperfectlylinearCTtobe500A.OnewayresistanceofthecableconnectingtheprotectivedevicetotheCTmaybeontheorderof.52ohms.IgnoringtheresistanceoftheCTandconnecteddevices,secondaryvoltageswouldreach2501,000voltsforaphasefault,and5002,000voltsforagroundfault.ThebiggestCTsmayberatedfor800voltsoutputbelowthekneepoint,sothis100:5CTwouldclearlysaturate.Therealoutputcurrentwouldlikelybeontheorderof150Aatthemost.

...AndtheaboveisignoringanyDCoffset,whichwouldcausetheCTtosaturateatunpredictableACcurrentlevels.EDIT

5.2KCONFIDENCEVOTES

Whathappenifmeasuringctisusedasprotectionct?

Electronic timers CT range Measuring and monitoring relays CM … · 2018. 5. 10. · timers and CM range measuring and monitoring relays from ABB offer many advantages to the user

GPU-accelerated method for measuring animal bone density from CT images

MODELOS: CT-Z1426LW CT-Z1416W CT-Z1426LW CT-Z1426W …€¦ · ct-z1416w ct-z1426lw ct-z1426w ct-g2156w ct-g2166lw . 1 contenidos generales 1. la fuente de alimentaciÓn y el ic803

Panasonic Ct g2150r Ct g2985s Ct f2120s Ct f2115m

2018 AGM Photos files/Photo Library/2018 … · tam ct tam :ttam ct tam ct tam am ct tam ct tam cttam cttam ct tam ct tam ct tam cttam cttam cttam ct tam cttam ct tan cttam :ttam

!Pd d - energia.gob.ar · vallejos ct loreto ct mburucuya ct mercedes ct palmar grande ct perugorria ct san miguel ct santo tome ct sta rosa corr ct paso de la patr ct la tablada

Guess Again (and Again and Again): Measuring Password ... · Measuring password strength by simulating password-cracking algorithms ... passwords that happen to meet ... Measuring

Measuring CT Concepts, Practices and Perspectives Through ...Linda Shear).pdf · Measuring CT Concepts, Practices and Perspectives Through Evidence-Centered Assessment. ... involves

Concept name similarity measure on SNOMED CT, Concept name ...ethesisarchive.library.tu.ac.th/thesis/2016/TU_2016_5822040902_6475_4523.pdf · 1.1 Text Similarity Measuring the similarity

FDG-PET/CT as an Imaging Biomarker Measuring - QIBA Wiki

Reliable measuring instruments and sensor …vt.baumer.com/fileadmin/user_upload/international/Downloads/BR-CT/...Reliable measuring instruments and sensor ... Pressure gauges and

Central Coast Ambient Monitoring Program CCAMP Summary of CCAMP Monitoring How we make CCAMP happen Making data available Measuring performance

CT prosedures CT ColonographyCT Colonography CT UrographyCT Urography CT AngiographyCT Angiography CT PerfusionCT Perfusion

Infrared Thermometer IR-CT 20 Dimensions - GHM GROUP · Infrared Thermometer IR-CT 20 Small infrared measuring head with 20:1 optical resolution Freely selectable and scalable analog

Exercise 2: Aerobic Capacity - Breakthroughs Happen …mhalter/PhysioLab1.pdfExercise 2: Aerobic Capacity ... Relationship between heart rate and oxygen consumption measuring VO 2

USE OF FILTER PAPER CHROMATOGRAMS TO DEMONSTRATE … · PAPER CHROMATOGRAMS IN ANTIGEN-ANTIBODY REACTIONS C CN CT CT CT 10 20 CT 40 CT CT CT CT CT CTil CT 80 160 320 640 1280 2560

CAS 140 CT - Color, Light, and LED Measuring Instruments 140 CT Array Spectrometer. ... LED Measurement LED Test & Measurement ... With add-ons such as CIE 127-compliant adapters for

Measuring Instruments Directive 2014/32/EU …...CT-004, 2018 Measuring Instruments Directive 2014/32/EU Thermal Energy Meters – OIML R 75, 2002 Page 3 of 13 Notes: 1. The column

Accidents Happen

Electronic timers CT-range Measuring and monitoring relays CM … · 2018-05-10 · Electronic timers CT-range Measuring and monitoring relays CM-range. easuring, monitoring and controlling:

Four Seasons Newsletter...Four Seasons Newsletter June 2019 MAKE MAGIC HAPPEN! MAKE MAGIC HAPPEN! MAKE MAGIC HAPPEN! MAKE MAGIC HAPPEN! On behalf of the entire faculty and staff at

CT range - ABB Group · D GOST K CB scheme E CCC Marks a CE b C-Tick existing pending CT-E Approvals CT-MFE CT-ERE CT-AHE CT-ARE CT-VWE CT-AWE CT-EBE CT-YDE CT-SDE CT-IRE CT-MKE CT-EKE

The Fairy Performance Assessment: Measuring …people.cs.vt.edu/~kafura/CS6604/Papers/Measuring-CT-Middle-Schools.pdfOne factor that limits the uptake of CT into K-12 is the lack of

CT Current transformers Ideal for measuring. Designed … · CT Current transformers Ideal for measuring. Designed to create efficiency. 13334_Trasf_Amp_CT_ENG_DEF.indd 1 15/04/14

Are We Measuring Conservation Effectiveness?...2010/06/06 · Are We Measuring Conservation Effectiveness? 3. RBM does not happen because it is not a priority in conservation culture

Review Classification of CT – CT “Proper” – Supporting CT – Fluid CT

Evolution will _______ happen if all five of the following happen!

CT SERIES BOILERS - Columbia Heating CT Series Manual.pdf · ct series boilers ct-6 ct-10 ct-15 ct-20 ct-25 ct-35 ct-50 installation, operation and maintenance manual columbia boiler

CT-1P Feature Ocular pressure measurement Measuring range … tecniche/CT-1P... · 2017-01-23 · Standard Option 1 Option 2 Option 3 Specifications Ocular pressure measurement Measuring

CT SERIES BOILERS - Columbia Heatingcolumbiaheating.com/certificates/pdf CT Series Manual.pdf · ct series boilers ct-6 ct-10 ct-15 ct-20 ct-25 ct-35 ct-50 installation, operation

MEASURING LEADERSHIP MEASURING LEADERSHIP MEASURING

Corresponding Tables Measuring systems for the continuous and … · 2016-10-05 · CT-005, 2010 Measuring system for the continuous and dynamic measurement for quantities of liquids

Sustainable Practices for BC Wineries...Implementing sustainable winemaking practices and measuring results is an ongoing process that does not happen overnight. Sustainability is