×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Motor Overload CTÆS

Motor Overload CTÆS

Motor Overload CTÆS

(OP)
I’ve come across two similar 60/1A ct’s, one is marked two primary turns, the other three  primary turns. Does this mean two / three primary turns respectively are required to give a 60/1 ratio in each case? To me, a 60/1A ct is 60/1 with one primary passing through???

Thanks in advance.

Alan

RE: Motor Overload CTÆS


If manufacturer’s literature is not available, a ratio check may be in order.  Excite the secondary at ~6 volts at line frequency and measure primary-side voltage with 1-3 turns through the primary window.  
  

RE: Motor Overload CTÆS

The ratio of both is 60/1. The turns are different.

The one with two primary turns must have 120 T in the secondary. The 3T must have 180 turns in the secondary. See the rated current capacity or Burden for each. Are them from the same manufacturer?

Be careful since open secondary of CT's could induce very high voltage. Better keep the secondary short circuited and test with a clamp on ammeter if current is circulated in the primary.

If test with voltage apply 120 VAC to the secondary (120 or 180 turns side) and measure the small induced voltage in the primary, less than 2 volts ( 2 or 3 turns), Get the CT ratio by the measured inverse volts ratio.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources