GE OSKF Instruction Manual page 13

Instruction Manual
With an infrared imaging device,
check if the primary terminal
connections are not overheating.
Compare with other CTs from the
same circuit.
After one year of operation, it is advised
a detailed inspection of tightening
torques and oil leakage and thereafter
twice per year according to the
substation maintenance contract.
If possible, GE suggests disconnecting
the CT and to perform the following
examinations:
1) Insulator: Depending on the pollution
level, it is necessary to clean the
porcelain;
2) Metallic components: check for
corrosion;
3) Tightening torque of primary and
secondary
adjustments shall be carried out as
described in the item "Primary
Terminals" of this document;
4) Secondary terminal box: If necessary
clean inside the terminal box.
5) Verify oil level indicator and if there
is any signal of oil leakage;
6) Remove the top cover to have access
to the bellows and verify if there is
any signal of oil leakage near the
fixation of the bellows and / or if the
bellows is in good condition.
Tests
It is recommended after the first few
hours of operation and whenever there
is a change in the CT primary current (in
the bar connection), performing the
© GE Grid Solutions
connections. Any
measurement of the primary terminal
temperature with a proper temperature
measuring instrument.
It is advised to perform the following
tests before putting the CT in operation
and thereafter at four year intervals
depending on availability of the CT:
1) Ratio (TTR);
2) Polarity (Polarity meter);
3) Saturation Voltage
source, Voltmeter and Ammeter);
4) Ohm Resistance
bridge);
5) Insulation Resistance
megohmmeter;
6) Tan δ of the HV insulation (Double
M4100, Omicron CPC100 or any
equivalent).
Important remark:
During commissioning and tests, it is
recommended recording the results
acquired in the tests abovementioned.
In case of doubts, please contact the
technical assistance support of GE: +55
35 3629 7042 or 7038 or 7000
(ac voltage
(Wheatstone
with any
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