When will you say that the CT is saturated?

When will you say that the CT is saturated?
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1 Answer

Answer :

When checking the CT with the secondary injection method a 10% increases in the voltage causes a 50% increase in the current the CT is said to be saturated. 
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Related questions

Before servicing the device indicated as 'A' in panels #1 and #3 of the illustration, the device labeled 'CT' must __________. EL-0003 A. have the disconnected leads taped to prevent short circuiting. B. only be connected to multimeter on the ammeter setting C. be short circuited D. have one lead grounded to discharge static electricity for the prevention of damage to electronic components

Description : Before servicing the device indicated as 'A' in panels #1 and #3 of the illustration, the device labeled 'CT' must __________. EL-0003 A. have the disconnected leads taped to prevent ... D. have one lead grounded to discharge static electricity for the prevention of damage to electronic components

Last Answer : Answer: C

Difference between Current Transformer (CT) and Potential Transformer (PT)

Description : Difference between Current Transformer (CT) and Potential Transformer (PT)

Last Answer : Current Transformers (CT) and Potential Transformers (PT) are used to measure the current and voltage in a circuit of the order of hundreds of amperes and volts respectively. A CT has large number of ... and flux density vary over a wide range whereas in PT, they vary over a limited range only

What are the errors in CT?

Description : What are the errors in CT?

Last Answer : (a) Ratio error Percentage ratio error = [(Nominal ratio – Actual ratio)/Actual ratio] x 100 The value of transformation ratio is not equal to the turns ratio. (b) Phase angle error: Phase angle =180/ [(ImCos -I1Sin )/nIs]

Where wound type CT used and where not used?

Description : Where wound type CT used and where not used?

Last Answer : Used where low CT ratio req. Not used where high short ckt. Current exists.

Give the details of switchyard 220 kV CB, Isolator, CT, CVT and lightning arrestor.

Description : Give the details of switchyard 220 kV CB, Isolator, CT, CVT and lightning arrestor.  

Last Answer : 220 kV SF6 Circuit Breaker 1. Make - ABB 2. Air pressure blocking a. Close Block - 17.3 bar. b. Open block - 16.7 bar. c. Auto reclose block - 19 bar. 3. SF6 pressure block a. Alarm - 5. ... , storage and erection. Rated voltage : 216 kV rms. Operating voltage : 184 kV rms. 

Why CT operated over load relay is using for loads of high acceleration time upto 30 seconds? How it getting back?

Description : Why CT operated over load relay is using for loads of high acceleration time upto 30 seconds? How it getting back?

Last Answer : The saturable current transformers linearly transforms the current upto twice the set current, but above this value the transformer core gets saturated and the secondary current is proportionally less. Thus ... overload. When current reduces the core gets de-saturated, as material design is such. 

How CT is connecting in ckt?

Description : How CT is connecting in ckt? 

Last Answer : If the primary of CT is delta connected load the CT will be in star connection and vice versa. This is because to have square root 3 time compensation. 

Why ICT are used?(INTERPOSING CT)

Description : Why ICT are used?(INTERPOSING CT)

Last Answer : To correct the system primary CT errors in case of high current faults out side CT zone (ICT’s primary CT is 800/1, but in fault current may go to thousands of amps. This ICT will take care of those errors. a) Matching the ratios. b) Matching the phase angle differences. 

Why core balance CT is preferred over residual connected CT’s to sense earth fault in 6.6 kV feeders?

Description : Why core balance CT is preferred over residual connected CT’s to sense earth fault in 6.6 kV feeders?

Last Answer : a) To avoid relay mal-operation due to CT saturation b) Better sensitivity is got. c) High pickup and TMS avoided in IDMT earth fault relay. 

What are the checks on CT & PT?

Description : What are the checks on CT & PT?

Last Answer : a) Polarity checks b) Insulation checks c) Ratio checks d) Knee point voltage (only for PS class CT)- magnetising characteristic test. 

Where CT secondary of 1A we are using?

Description : Where CT secondary of 1A we are using?

Last Answer : For long distance current transmission, to reduce the IR drop.  

What is the purpose of CT & PT?

Description : What is the purpose of CT & PT?

Last Answer : For transformation of current, voltage to a lower level for the purpose of Measurement, Protection and Control. 

What is the standard CT polarity?

Description : What is the standard CT polarity?

Last Answer : Primary current enters at P1 and secondary current leaves at S2.  

But is it advisable to keep the secondary of CT in open conditions? Will not induce very high voltage?

Description : But is it advisable to keep the secondary of CT in open conditions? Will not induce very high voltage?

Last Answer : If the CT has only one secondary winding, we should keep it always short cktd for safety, but if the CT has multiple secondary, then if one secondary voltage is kept limited by suitable loading, then the other secondary voltage is eventually limited proportionately. 

A CT has 2 – secondary windings. If we use only one secondary winding can we keep the unused secondary winding short circuited?

Description : A CT has 2 – secondary windings. If we use only one secondary winding can we keep the unused secondary winding short circuited?

Last Answer : No. If it is short-circuited then the ratio will not get correctly. The turns of primary winding will be shared between 2 secondary windings. So the unused secondary winding should kept open. 

What is over voltage interturn test for CT?

Description : What is over voltage interturn test for CT?

Last Answer : With secondary open, pass rated current in primary for 1 min. Then check secondary for insulation. 

What is the operating point in the Magnetising characteristic of protection CT & measuring CT?

Description : What is the operating point in the Magnetising characteristic of protection CT & measuring CT? 

Last Answer : Protection CT – Operation at ankle point only. Measuring CT – Operation from ankle to knee point 

What are the errors of the following CT’ s 5p. 10p. 15p. At rated current?

Description : What are the errors of the following CT’ s 5p. 10p. 15p. At rated current?  

Last Answer : 5p - 1 % Ratio error ± 60 min phase error 10p - 3 % Ratio error ± 60 min phase error 15p - 5 % Ratio error ± 60 min phase error 

What are the specifications of CT?

Description : What are the specifications of CT? 

Last Answer : Protection CT - Error. Alf. KpV. Metering CT - Error. Burden. Differential CT - Class PS. Core balance or E/F CT - 5-p type. Primary current - Rating of CT - 1. 15 ( full load current ) Short time rating - 1 sec. 

Why CT should not be open circuited?

Description : Why CT should not be open circuited?

Last Answer : Very high voltage will be induced in secondary due to less back emf resulting in the failure of the insulation. 

How can you de-saturate the CT?

Description : How can you de-saturate the CT? 

Last Answer : Pass ac current through the primary and vary the current from zero to maximum with secondary in shorted condition. Pass dc current in the secondary and vary it from zero to maximum.

What is the problem anticipated due to CT saturation?

Description : What is the problem anticipated due to CT saturation?  

Last Answer : The CT will not be able to drive the current through the circuit causing nonoperation of relays. In some other case when the currents in the two phases are compared for relay operation the relay may operate due to unbalance. 

Show the CT characteristics.

Description : Show the CT characteristics.

Last Answer : CT characteristics :  

How to reduce the CT error?

Description : How to reduce the CT error? 

Last Answer : Error reduces if load increases.  

Explain with simple diagram the core balance CT.

Description : Explain with simple diagram the core balance CT.

Last Answer : In core balance CT all the three phases go through the core and the resultant magnetic flux is zero. Because the flux of three phases cancel each other. So the secondary output of CT is zero and ... energised to trip the circuit. Saturation is no problem because the core size is very big.  

Explain the procedure for finding out the polarity and ratio test in a CT with circuit diagram.

Description : Explain the procedure for finding out the polarity and ratio test in a CT with circuit diagram. 

Last Answer : Polarity test: Connect the circuit as shown in figure with a battery, switch and AVOmeter. Now momentarily close the switch S and see the deflection in the AVOmeter. If it is in the direction as shown in the ... A2. Then see whether it confirms to reading of nameplate. Ratio = A1/A2. 

Define knee point voltage of a CT.

Description : Define knee point voltage of a CT.

Last Answer : When the primary of a CT is open circuited and supply (variable) of system frequency is given to secondary, then a 10% increase in voltage constitutes 50% increase in current. That voltage is the knee point ... Above kpv the ratio of transformer will not be applicable. kpv = RCT + RLEADS + RRELAY  

Where core balance CT is used?

Description : Where core balance CT is used?

Last Answer : Core balance CT is used in earth fault protection.  

Draw a neat sketch and explain the use of CT and PT for measurement of power in a single-phase circuit?

Description : Draw a neat sketch and explain the use of CT and PT for measurement of power in a single-phase circuit?

Last Answer : If wattmeter of proper range is not available or if voltage and current ranges are high we can usr CT and PT of suitable ratio. Connect the CT and PT as shown in figure. The reading of wattmeter can be multiplied by the ratio to get the actual power.   

The boundary of the protective zone is determined by the (A) Location of CT (B) sensitivity of relay used (C) Location of PT (D) None of these

Description : The boundary of the protective zone is determined by the (A) Location of CT (B) sensitivity of relay used (C) Location of PT (D) None of these

Last Answer : Ans: B The boundary of the protective zone is determined by the sensitivity of relay used. If the relay is more sensitive, the protective zone will be increased.

What is the colour of silica gel in dry stage and when saturated with moisture in a breather?

Description : What is the colour of silica gel in dry stage and when saturated with moisture in a breather?

Last Answer : Dry stage – Deep blue Saturated stage – Whitish pink

What is the colour of silica gel in dry stage and when saturated with moisture in a breather?

Description : What is the colour of silica gel in dry stage and when saturated with moisture in a breather?

Last Answer : Dry stage – Deep blue. Saturated stage – Whitish pink. 

What is the relative humidity for a saturated air? A. 0% B. 50% C. 100% D. cannot say

Description : What is the relative humidity for a saturated air? A. 0% B. 50% C. 100% D. cannot say

Last Answer : ANSWER : C

Can I get an MRI for a cardiac calcium score rather than a CT?

Description : Can I get an MRI for a cardiac calcium score rather than a CT?

Last Answer : Check with your cardiologist to be sure. I listen to the medical channel on SirisuXM (#110) - they had a session on this about a month ago. I don't recall all the details, but I do ... of anything. It's more of a general guidepost than anything that is actionable. You have probably seen this

Can a CT colonography show cancer in organs surrounding the bowel?

Description : Can a CT colonography show cancer in organs surrounding the bowel?

Last Answer : answer:What are you trying to say? A colonography a year ago and that showed I had a kidney stone has nothing to do with a tumor in my stomach . Comments you have before show you ... able to found in your stomach. GERD is treatable-take an antacid or Prilosec (omeprazole) for Heartburn relief.

Why is the CT colonography prep so damn dangerous?

Description : Why is the CT colonography prep so damn dangerous?

Last Answer : Yes I did it. I was put under and had no side effects. Drinking that liquid was hard.

Anyone here had a CT Colonography?

Description : Anyone here had a CT Colonography?

Last Answer : My husband has had a colonoscopy and endoscopy. He said they gave him an anaesthetic, so he was unconscious during the procedure and he felt perfectly fine afterwards.

What could my doctor be looking for with a CT scan of my head?

Description : What could my doctor be looking for with a CT scan of my head?

Last Answer : Brain tumors, blood clots leading to potential aneurisms, any abnormalities that may be causing your symptoms.

What does it feel like to have a CT scan?

Description : What does it feel like to have a CT scan?

Last Answer : answer:It doesn't feel like anything. You just lie on something that is like a stretcher while this circular machine sort of whirrs around. You can close your eyes and relax. Follow directions (in ... when instructed). It doesn't hurt at all. I had a couple abdominal CTs after abdominal surgery.

Is it not true that MRI's and CT scans cannot pick up cancer cells?

Description : Is it not true that MRI's and CT scans cannot pick up cancer cells?

Last Answer : No, they do not see individual cancer cells. They do, however, do a very good job of finding small tumors.

Why might a doctor order a pelvic/abdominal CT scan after a colonoscopy?

Description : Why might a doctor order a pelvic/abdominal CT scan after a colonoscopy?

Last Answer : It could be any irregularity that they saw in your blood work. You could call your doctor and ask.

Is it common to get a headache after a CT scan or x-ray?

Description : Is it common to get a headache after a CT scan or x-ray?

Last Answer : It could be caused by tension and anxiety and once the scan is over your body is no longer processing adrenalin to get you through it.

Stemming from the massacre in Newtown CT: What do you think should be done about the issue of the severely mentally ill receiving treatment for their illness, both for their own sake and for the benefit of society?

Description : Stemming from the massacre in Newtown CT: What do you think should be done about the issue of the severely mentally ill receiving treatment for their illness, both for their own sake and for the benefit of society?

Last Answer : answer:I'm not sure what should be done, because I'm not a mental health expert. But I would caution against some sort of he doesn't want treatment, so let's lock him up mentality. ... /disorder/syndrome or another. Mostly minor, and mostly well compensated for, but-none of us are without issues.

What are some possible causes for a small mass found during a chest CT scan?

Description : What are some possible causes for a small mass found during a chest CT scan?

Last Answer : I know that you lived in Vegas as a child. I’m wondering if the nuclear testing they used to do in the desert has anything to do with it? {{{Hugs}}} and prayers and good thoughts sent to you.

How high is the risk of cancer from CT scans?

Description : How high is the risk of cancer from CT scans?

Last Answer : I found this article on multiple sites (although all of them not-exactly-unbiased, since they were radiology service type sites).

Are CT Scans still effective without dye or contrast?

Description : Are CT Scans still effective without dye or contrast?

Last Answer : answer:I don't know much on the topic, but I think the dye shows blood vessels and blood flow most of all. If you had contract with your MRI, which would be an MRA I believe, then they likely ... get it, especially if you are older. Sorry to hear about the tumour, I hope everything will be ok.

Is a CT scan necessary to detect a broken neck/spine, or is a regular xray sufficient?

Description : Is a CT scan necessary to detect a broken neck/spine, or is a regular xray sufficient?

Last Answer : It might injure the area further to do the manipulations necessary for clean x-rays. Whereas, with a cat scan the spine can stay immobilized.

Is it possible to cross-rate from IT to CT in the Navy?

Description : Is it possible to cross-rate from IT to CT in the Navy?

Last Answer : I doubt a website can answer your question adequately. This is something that is site specific, and only your unit commander can help you.

Is Danbury CT too far a location to commute to NY airports?

Description : Is Danbury CT too far a location to commute to NY airports?

Last Answer : I would think that if you don’t fly all that often that 90 mins. would be acceptable.

Strange symptoms after head CT?

Description : Strange symptoms after head CT?

Last Answer : Your experience would have nothing to do with the CT scan.