Previous in Forum: MV-Panels and MCC for chillers   Next in Forum: CURRENT INJECTION TEST
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
6 comments
Rate Comments: Nested
drajesh1985
Active Contributor

Join Date: Feb 2008
Posts: 18

difference between 1000/5A C.T & 1250A/5A C.T

10/16/2008 2:32 AM

what is the difference between using 1000/5A C.T & 1250A/5A C.T, while measuring the output from a 1000A ACB
Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Good Answers:

These comments received enough positive votes to make them "good answers".
Anonymous Poster
#1

Re: difference between 1000/5A C.T & 1250A/5A C.T

10/16/2008 3:53 AM

SORRY,

CAN YOU EXPLAIN WHAT YOU MEAN?

THANKS
Register to Reply
2
Sapper
Power-User
Australia - Member - New Member Hobbies - Target Shooting - New Member Popular Science - Weaponology - New Member

Join Date: Dec 2007
Location: Sydney Australia
Posts: 480
Good Answers: 35
#2

Re: difference between 1000/5A C.T & 1250A/5A C.T

10/16/2008 4:14 AM

The reading at your meter will be different by up to 20%.

The 1000A/5A needs 1000A to deliver a 5A Full Scale Deflection (FSD) to measure on your Meter.

The 1250A/5A needs 1250A to deliver a 5A FSD to measure on your Meter.

So if you are using a 1250A/5A on a 1000A circuit you get a vaulue of 4A at the meter, using the 1000A/5A on the same circuit you get a value of 5A.

Obviously the actual figures will depend on the scale of the Meter as I would expect it to be calibrated to the values being read

Regards,
Sapper

__________________
 It's all about the Boom! - MythBusters
Register to Reply Good Answer (Score 2)
No more Good Answers.
Sparkstation
Guru
New Zealand - Member - Interested in everything- see my Profile please APIX Pilot Plant Design Project - Member - Member Engineering Fields - Electrical Engineering - Member Engineering Fields - Power Engineering - Member Engineering Fields - Civil Engineering - Member Hobbies - Musician - Autoharp and Harmonica Hobbies - Hunting - Member Hobbies - Fishing - Member

Join Date: Nov 2007
Location: Christchurch, (The Garden City), South Island, New Zealand
Posts: 4395
Good Answers: 230
#5
In reply to #2

Re: difference between 1000/5A C.T & 1250A/5A C.T

10/16/2008 5:35 AM

Hello Sapper

from me

Your answer says it all.

Kind Regards....

__________________
 "The number of inventions increases faster than the need for them at the time" - SparkY
Register to Reply Off Topic (Score 5)
cnpower
Guru
Engineering Fields - Control Engineering - New Member China - Member - New Member

Join Date: Sep 2006
Location: CHINA
Posts: 2945
Good Answers: 14
#3

Re: difference between 1000/5A C.T & 1250A/5A C.T

10/16/2008 4:52 AM

#2 is right. they have different ratio. and the later has a little more precision than the front and get less current from line.
Register to Reply
TITO60
Associate

Join Date: Sep 2007
Posts: 54
Good Answers: 3
#4

Re: difference between 1000/5A C.T & 1250A/5A C.T

10/16/2008 5:13 AM

Hi drajesh1985,

The difference between using 1000/5A & 1250/5A CTs in metering shall result in correct/incorrect direct reading on the meter.

For example: Let us assume the load current is 600A, and the scale of your ammeter is 1000A;

Case # 1: Using 1000/5A CT

The Primary Current (Ip) = 600A

The Secondary Current (Is) = 3A, corresponds to 600A primary current. Accordingly, the meter shall indicate 600A, (correct direct reading).

Case # 2: Using 1250/5A CT

Ip= 600A

Is = 2.4A, corresponds to 600A primary current. Accordingly, the ammeter shall indicate incorrect direct reading. Therefore, you have to multiply the ammeter reading by a correction factor to get the correct one.

Regards,
Register to Reply
ramvinod
Guru

Join Date: Jun 2007
Location: chennai,India
Posts: 592
Good Answers: 19
#6

Re: difference between 1000/5A C.T & 1250A/5A C.T

10/19/2008 1:54 PM

There is no difference.You can use 1250/5 ct on 1000 amps Circuit.Only thing is the instrument connected to the CT should be calibrated for 1250/5 ct ratio,now a days the digital meters can be programmed for any CT ratios at site.

__________________
 Ramesh,Freelance Electrical/automation Consultant
Register to Reply
Register to Reply
Have a Different Question?
6 comments

Good Answers:

These comments received enough positive votes to make them "good answers".
Copy to Clipboard

Users who posted comments:

Anonymous Poster (1); cnpower (1); ramvinod (1); Sapper (1); Sparkstation (1); TITO60 (1)

Previous in Forum: MV-Panels and MCC for chillers   Next in Forum: CURRENT INJECTION TEST

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
Electrical Engineering:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (47 right now)
Show Members
Advertisement