Hi all,
Just need to verify some doubts..
IEC 60599 Guide to interpretation of Dissolved Gas Analysis
Page 49.
I have 2 readings of Ethane taken in Nov 2003 & Dec 2003.
PPM is as such:
Nov 2003 - 52ppm
Dec 2003 - 106ppm
Oil Vol - 7950 cubic meters
number of days interval - 15
Using the...
Hi, I understanding that a CT secondary shall not be open circuited due to the built up of high voltage across the CT secondary terminal. However, does this means that all CT secondary shall have shorting links?
We have a CT feeding into a earth leakage relay (ELR) and when the ELR is faulty...
Hi all,
I found a earth cable linking the excitation transformer (230kV/660V) LV terminal box to the generator excitation panel (earth bar). The power cables from the transformer to the panel is single core without screen/shealth.
I was wondering what is the purposes for this earth cable?? If...
Hi all,
I was told that the motor housing plays a part in containing the magnetic flux generated when the 3 phase volatge is applied to the stator. Is this true?
If there is a hole in the housing (happened actually, I ahve this motor which is exposed to acid and the acid actually burnt a hole...
Hi all, just a theory question to ask.
We know that relay coils make use of electromagnetic principle (DC) for activation. But what about AC relay coils? Is there any rectification circuit inside the relays? I am referring to those tiny auxiliary relays.
Thanks in advance for enlightening!
Hi all,
What are the recommended UPS maintenance? Here i am referring to Inverters and Chargers only.
We are using AEG Saft Protect Inverters and Profitec Chargers. They consists of mainly electronics cards, capacitors and the usual. I am not too sure how to maintain a system that depend...
Hi, it's me again..
Just like to check on something that i dun really understand..
I am asked to use a test voltage of 500V to megger the 400V breakers but use 5kV to megger 6.6kV breakers. Are the test voltages correct respectively? If it is, that why is it that we use a higher than rated...
Hi all
May i ask is it necessary to do a megger test on a 400V MCC busbar for a shutdown maintenance? I have limited manpower and time, thus i would like to give this item a miss. Please advise if there is any standards that recommends maintenance for LV switchgear? Thanks!
Hi,
Just a bit confused over the use of "choke" and "filter"..
When is a "choke" (inductor) use? And when is a "filter (Capacitor & resistor) used? What I understand is that both are used for filtering purposes, pls correct me if I am wrong...
Thank u!!!
czping
