×
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

High voltage equipment terminal temperature rating

High voltage equipment terminal temperature rating

High voltage equipment terminal temperature rating

(OP)
Does anyone know if there is a standard terminal temperature rating for high voltage equipment?  I was thinking that it was 90°C but am not sure.  I've tried looking at some IEEE standards but haven't found anything yet.

RE: High voltage equipment terminal temperature rating

IEC60943: 1998 Guidance concerning the permissible temperature rise for parts of electrical equipment, in particular for terminals.

RE: High voltage equipment terminal temperature rating

(OP)
I don't have access to that standard.  Any chance you could give me a little more detail before I spend $400 to get a copy?

RE: High voltage equipment terminal temperature rating

Mudcat,

If the installation is ruled by NFPA the answer is 90 °C.

As per NEC 2011 Article 110 (Requirements for Electrical Installations), Part III (Over 600 Volts, Nominal)see the following articles:

110.30 General. Conductors and equipment used on circuits over 600 volts, nominal, shall comply with Part I of this article and with 110.30 through 110.40, which supplement or modify Part I. In no case shall the provisions of this part apply to equipment on the supply side of the service point.

110.40 Temperature Limitations at Terminations. Conductors shall be permitted to be terminated based on the 90°C (194°F) temperature rating and ampacity as given in Table 310.60(C)(67) through Table 310.60(C)(86), unless otherwise identified.

Hope this helps

RE: High voltage equipment terminal temperature rating

C57.19.00 says 30K rise over 30C average 24 hr ambient, 40C maximum ambient.

RE: High voltage equipment terminal temperature rating

Your understanding of max temperature of 90 C for terminals to be connected to external conductors is correct. If the terminals are tinned or silverplated,limit temperature is 105C. In both cases temperature rise shall be limited to a max of 60 or 75 C.

In IEC, the above limits are specified in various product standards eg Table 2 of IEC 60137-2008 Transformer Bushings, Table 2 of IEC 60947-1:2010 Low Voltage Switch gear and Control Gear,Table3 of IEC 62271-1:2007 High Voltage switchgear and Control Gear Part 1 Common specifications etc.

IEC/TR 60943ed2.1: 2009 is the Technical Report on Guidance concerning the permissible temperature rise for parts of electrical equipment,in particular for terminals. This classic tutorial elabortae the theory behind above temperature rise limits.This 60 page document is value for money covering theory and application.Table 4 gives comparative values of contact resistance, and table 6 typical values of temperature rise and temperature limits  for various connections-bolted,spring contcat etc.

I could not find appropriate IEEE std on the subject. Stevenal,I could not find the values in C57.19-2004.Clause 5.4.1 gives 75K/ 65K as temperature rise  

RE: High voltage equipment terminal temperature rating

Section 4.1, Usual service conditions.
5.4.1 speaks of the thermal basis for the continuous current rating. 75 K rise is the hottest spot on the bushing, 65 K is for the oil the lower part of the bushing is immersed in.
I believe Section 4 is more appropriate for an application question, since 5.4 is more about how the current rating was derived.
Also see 4.2 for unusual service.

RE: High voltage equipment terminal temperature rating

Thank you Stevenal! I missed it.But 70C absolute temperature looks too low compared to IEC  standards values of 90C (uncoated) and 105C ( Tinned or silver plated)

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