|
Home > Archive > Electrical Engineering > April 2007 > Transformer check
You are viewing an archived Text-only version of the thread.
To view this thread in it's original format and/or if you want to reply to
this thread please [click here]
|
|
| obeng.appiah@gmail.com 2007-04-19, 1:25 pm |
| Our factory is currently being fed by a dedicated 50KvA transformer
taking its source from a 33Kv line.
We have however been experiencing voltage drops on the BLUE phase to
about levels of 150volts (with the RED and YELLOW phases at about
220volts) when we switch on our equipment. Our total three phase motor
KW rating is about 37.5 and anytime we start up to 20KW of these
motors they cut off due to the quality of supply from the BLUE phase.
We also do not have any other loads on these phases when the motors
are on.
We shall be grateful if you could help.
We hope our request receives the required attention.
Thank You,
Michael Obeng Appiah
(For: Pavetech Ltd.)
| |
| phil-news-nospam@ipal.net 2007-04-19, 8:25 pm |
| On 19 Apr 2007 09:55:58 -0700 obeng.appiah@gmail.com wrote:
| Our factory is currently being fed by a dedicated 50KvA transformer
| taking its source from a 33Kv line.
|
| We have however been experiencing voltage drops on the BLUE phase to
| about levels of 150volts (with the RED and YELLOW phases at about
| 220volts) when we switch on our equipment. Our total three phase motor
| KW rating is about 37.5 and anytime we start up to 20KW of these
| motors they cut off due to the quality of supply from the BLUE phase.
| We also do not have any other loads on these phases when the motors
| are on.
|
| We shall be grateful if you could help.
It sounds like something for your power utility to address, especially
if they own/maintain the transformer(s). It could be a bad primary
connection. There are many other possibilities, too.
It might help to know how the transformers are wired (D-D, D-Y, etc).
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-04-19-2006@ipal.net |
|------------------------------------/-------------------------------------|
| |
| John Rye 2007-04-20, 3:25 am |
| Hello Michael
In article <1177001758.735691.259350@b58g2000hsg.googlegroups.com>,
<obeng.appiah@gmail.com> wrote:
> Our factory is currently being fed by a dedicated 50KvA transformer
> taking its source from a 33Kv line.
> We have however been experiencing voltage drops on the BLUE phase to
> about levels of 150volts (with the RED and YELLOW phases at about
> 220volts) when we switch on our equipment. Our total three phase motor
> KW rating is about 37.5 and anytime we start up to 20KW of these
> motors they cut off due to the quality of supply from the BLUE phase.
> We also do not have any other loads on these phases when the motors
> are on.
It is difficult to make any suggestions on the basis of the information that
you have provided. Induction motors can easily take 5 times full load
starting, so with a total of 37.5 HP on a 50 kva transformer I would expect
to see very significant dips during starting.
What are the three line to neutral voltages on no load, and the three line to
line voltages on no load ?
John
--
John Rye
Hadleigh IPSWICH England
<http://web.ukonline.co.uk/jrye/index.html>
---< On Line using an Acorn StrongArm RiscPC >---
|
|
|
|
|