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MCT vs PCT

Created by: jeet2907 at: 5/26/2014 6:49 PM (6 Replies)

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5/26/2014 6:49 PM
jeet2907 Posts: 235 Rating: (52)	Dear All What id the defference betn Measuring CT and Protection CT?? Can i used measuring CT for protrxtion purpose??? If no then why???
jeet2907 Posts: 235 Rating: (52)
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5/26/2014 8:41 PM	Rate (1)
kinjalpatel1899 Advanced Member Joined: 2/12/2013 Last visit: 12/6/2023 Posts: 61 Rating: (15)	Protection CT will have to carry the faultcurrents which are 10 or 20 times(watever the requirement) the normal full load currentthat is why it is designed at much below the saturation point(knee) inorder to aviod saturation. Measuring CT will have to carry only full loadcurrent that is why it is designed near to knee point.and that is why we can not use this CT for protection purpose...

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5/26/2014 11:43 PM	Rate (1)
Madhava Silver Member Joined: 11/26/2011 Last visit: 6/29/2023 Posts: 508 Rating: (23)	jeet2907 Dear All What id the defference betn Measuring CT and Protection CT?? Can i used measuring CT for protrxtion purpose??? If no then why??? Other than kinjan told, 1. Accuracy class: Metering needs high accuracy at load current while Protection need not have that high accuracy. 2. Safety Factor: It determines the multiplicity of load current at which the CT saturates. Metering ct should have lesser value so that it saturates before the meters can get damaged due to some abnormality. Protection should have high value since its main purpose desires the ct to withstand high fault currents to be sensed back to the relays.

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5/27/2014 6:23 AM
jeet2907 Posts: 235 Rating: (52)	kinjalpatel1899 Protection CT will have to carry the faultcurrents which are 10 or 20 times(watever the requirement) the normal full load currentthat is why it is designed at much below the saturation point(knee) inorder to aviod saturation. Measuring CT will have to carry only full loadcurrent that is why it is designed near to knee point.and that is why we can not use this CT for protection purpose... Dear Kinjal I have one more doubt abt to measuring CT. Measuring CT shuould be damaged during SC in the system due to the high current passing through it???If not then why not????
jeet2907 Posts: 235 Rating: (52)
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5/27/2014 9:31 AM	Rate (1)
Madhava Silver Member Joined: 11/26/2011 Last visit: 6/29/2023 Posts: 508 Rating: (23)	jeet2907 kinjalpatel1899 Protection CT will have to carry the faultcurrents which are 10 or 20 times(watever the requirement) the normal full load currentthat is why it is designed at much below the saturation point(knee) inorder to aviod saturation. Measuring CT will have to carry only full loadcurrent that is why it is designed near to knee point.and that is why we can not use this CT for protection purpose... Dear Kinjal I have one more doubt abt to measuring CT. Measuring CT shuould be damaged during SC in the system due to the high current passing through it???If not then why not???? it has been mentioned in the second point Safety Factor. There is a chance for getting damaged. And CT will be also having a low saturation point.

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5/27/2014 11:54 AM
ashishmistry390 Posts: 21 Rating: (0)	jeet2907 Dear All What id the defference betn Measuring CT and Protection CT?? Can i used measuring CT for protrxtion purpose??? If no then why??? Dear Sir, CT is used to measure the transmission current. Transmission currents are very high so cannot messure directly.first to step down the current and then measure the current using some ratio.CT protection is used to avoide the aceident and eleminating losses. Regards, Ashish Mistry
ashishmistry390 Posts: 21 Rating: (0)
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5/27/2014 1:41 PM	Rate (0)
SMHZ Bronze Member Joined: 10/19/2012 Last visit: 4/17/2022 Posts: 315 Rating: (9)	Simply put: A CT is a Current Transformer, it will step the current down to a safe level that can be easily measured. A metering CT would be in large services, to step the current down before it goes to the power company's meter. A protective CT would be attached to some types of motor starters and watches for the current to rise to an unsafe level and cause the starter to shut off.

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