ABB THF Series Installation And Operation Instruction Manual

2247 0191/ 1SCC330001M5803
Installation and Operation Instruction for THF Filter and
Protective Unit THF 1_
General guidelines
Due to the fact that most UK building earth circuits are TN-S-systems, special care should be
taken when installing a THF system in this country.
As with all other THF installations, the device should be fitted in the Neutral conductor, however
the following guidelines should be followed:
THF should be installed in the Neutral
•
conductor at the Transformer Star
Point.
In N- conductor in transformer star
•
point: Care should be taken to ensure
that no earth/neutral bond exists on the
supply (transformer) side of the filter.
This may result in a bypass situation
causing excessive current to flow via
the system earth.
THF 1S_
•
•
In case of installation in N-conductor
of TN-S- system: Prior to installation of
THF, resistance measurements must
be carried out between the downstream
(building) earth & neutral to ensure that
no erroneous earth/neutral connection
exists other than that intended
to achieve a TN-S-system. Such
accidental connection could cause
excessive current to flow in the system
earth.
This Installation and setting instructions
for the THF-1S protection unit and
brochure THF 1 GB and 2 GB should
be followed.
THF
34 THF 1S1 C
THF 1BS_