17
Figure 35: Three-position disconnector.
4.4.3. Instrument transformers
a) Voltage transformers (Figure 36).
The resin-insulated voltage transformers are used for
supplying measurement instruments and protections.
They comply with IEC 61869-1, IEC 61869-3 which
have fully replaced previous standard IEC 60044-2.
They are installed in the fixed version and their
dimensions comply with DIN Standards 42600 Narrow
Type. Their performances and accuracy classes
comply with the functional requirements of the
apparatus they are connected to.
On request, the voltage transformers are equipped
with fuses or removable links (Figure 36).
Replacement of the fuses (chapter 7.5) must be
carried out with the power circuit de-energized.
For the ENA version, access to the voltage
transformer compartment is controlled by a key
interlock which ensures that the VT compartment
cover cannot be removed unless the three-position
disconnector is in the earth position and the circuit-
breaker is closed.
WARNING
Before removing the voltage transformer
compartment cover, make sure that cables are
earthed (three-position disconnector in EARTH
position and circuit-breaker is closed).
Figure 36: Instrument transformers
1 Voltage transformer
2 Removable links
3 Current transformer
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