4
AT CU R R E NT I N STRU M E NT TR A N S FOR M E R
I N S T R U C T I O N S FO R I N S TA L L AT I O N , USE A N D M A I N T EN A N C E
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02 AT35/41 mouting
points
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03 AT38 mounting
points
2.
Ground always the metallic base of the
instrument transformer.
3.
Connect always one terminal of each sec-
ondary winding of the transformer to the
earth. When the secondary of trans-
former is interconnected, there should
be only one grounded point to prevent
accidental paralleling with system
grounding wire.
4.
Always short-circuit the secondary of the
current transformer, which is not cur-
rently in use, to prevent secondary volt-
ages, which may be hazardous to per-
sonnel or damaging to the transformer’s
secondary. The secondary like this must
be additionally grounded.
Mounting
Mounting points are showed on picture below
The AT transformer is mounted in different
ways-using rings to fix the transformer directly to
the bushing, using flanges, or other ways of fixa-
tion. The mounting is not a part of transformer
delivery and the customer is fully responsible for
installation in the right way.
Tightening torques
AT35 (M12)
30 Nm
AT38 (M16)
30 Nm
AT41 (M16)
50 Nm
The producer has not any liability for incorrect
mounted form or possible consequences of it.
Nuts and threaded rots are delivered on cus-
tomer request.
Connection of transformer primary side
The AT transformers don´t have its own primary
conductor. The primary conductor is designed as
a bushing with its own insulation, or insulated ca-
ble.
Connection of the transformer secondary side
Secondary outlets are marked by color. Which
color is assigned to which wire you can see in ta-
ble below.
Outlets marking
test wire (measure side)
black marked with M
test wire (earth side)
black mark with Ground
screen earth
black mark with Ground
secondary wire xS1
(X1, Y1, Z1, U1, V1, W1)
black and marked with core/
terminal no.
secondary wire xS2
(X2, Y2, Z2, U2, V2, W2)
red and marked with core/
terminal no.
secondary wire xS3
(X3, Y3, Z3, U3, V3, W3)
yellow and marked with core/
terminal no.
secondary wire xS4
(X4, Y4, Z4, U4, V4, W4)
blue and marked with core/
terminal no.
secondary wire xS5
(X5, Y5, Z5, U5, V5, W5)
grey and marked with core/
terminal no.
secondary wire xS6
(X6, Y6, Z6, U6, V6, W6)
brown and marked with core/
terminal no.
4. Instructions for use
Current instrument transformers are used:
• to convert large currents in the primary circuit
to an appropriate level for secondary circuit
equipment (relays and meters);
• to insulate primary and secondary circuit from
each other to protect the secondary equipment
from the harmful effects of large current ap-
pearing during the operation (short circuits).
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02
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03
Mounting points
Lifting points
Mounting points
