ABB THF 1BS Series, Installation And Operation Instruction Manual

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2 3 2
switch.
3.
Care should be taken to ensure that no
earth/neutral bond exists on the supply
(transformer) side of the filter.
•
150/180 Hz current: 7% of the rated primary current of current transformer ( T1).
This current can cause overheating in case of fault in the TN-S-system.
•
Time settings 0,5 sec.
•
50/60Hz current exceeds 50% of the rated primary current of current
transformer (T1). This current is a cause of increased unbalance voltage.
Installation and operation instruction for THF filter and
protective unit THF 1_
Connection to the network need to be done by authorised and skilled personnel only.
Installation to TN-C-System -
THF in the transformer star point
The installation shall be done following the local
wiring rules suggesting to work all power off.
Prior to installation of THF in the transformer star-
point between point A and B following measures
must be taken.
1.
Measure the fundamental 50/60Hz current in
the star point connector conductor. Load balancing
is recommended, if the unbalance current exceeds
15% of the rated primary current of the CT.
2.
Open both the HV-main switch and the LV-main
This may result in a by-pass situation causing exces-
sive current to flow via the system earth, heating of
the cables and inactivating the THF.
4. Measure the isolation resistance between point A
and B to ensure that the resistance between point A
and B is high. R
e
needs to be over 50 k
Ω
.
Any earthing conductor with lower resistance by-
passing the THF between the star point and B might
be subject to high third harmonic current, which can
cause heating of the cables.
5.
Make the earthing in point B.
The installation of THF
6. Before the installation turn the by-pass switch of
THF-unit ON.
7. Connect the OUTPUT-terminal to the load
side(B).
8. Connect the INPUT-terminal to the line side (A).
9. The PEN-wire shall be earthed after the OUTPUT-
terminal only. No earthing is allowed between the
transformer star point (N-terminal) and the INPUT-
terminal.
10. After the installation turn the by-pass-switch in
OFF-position.
11. Check that the THF connection is right by measu-
ring the current with THF ON and OFF.
In proper installation the filtering effect should be
around 90 % and the 150/180 Hz voltage across THF
should be 10...45V.