High Frequency Current Transformer (Hfct) - GE Kelman DGA 900 Plus Installation & Commissioning Manual

9.4.2.14 To compress the sealing O-ring evenly, tighten the five screws progressively
working across the circle rather than around the circle of screws as illustrated
in Figure 9-12. Tighten the screws to the torque specified in the installation
drawing (46-XXXX) provided with each Bushing Adaptor.
Figure 9-12: Tightening order
WARNING: Ensure that the Bushing Adaptor has been assembled carefully
with the liquid tight fitting and conduit to form a liquid tight connection.
Water ingress inside the bushing may result in catastrophic failure.
If the cabling is being routed as part of the pre-installation work, then ensure that the
phase is properly identified on each coaxial cable.
Ensure that the serial number of the bushing adaptor matches the phase of the bushing
to which it is connected. For the bushing mappings, refer to Section 10.3 Configuration in
'MA-040 – DGA 900 Plus – Operator Guide'.
It is crucial that the Bushing Adaptor circuit integrity tests in Section 9.8 are
performed for each bushing.
9.5

High Frequency Current Transformer (HFCT)

WARNING: The HFCT must be installed on a ground cable or bar going
from the high voltage neutral bushing (typically identified as H0) directly to
ground. There must not be any open switches between the path to ground
from the neutral bushing while the transformer is energized.
WARNING: If there is a switch on the path to ground from the high voltage
neutral bushing as shown in Figure 9-13, the HFCT must NOT be installed
between the switch and the neutral bushing, because if for any reason the
switch is opened there will no longer be a direct path to ground causing a
potentially hazardous condition.
MA-041 – DGA 900 Plus - Installation & Commissioning Manual - Rev 1.1 4-Mar-22 Page 47 of 99