MA-005 - Minitrans Installation Manual - Rev 4.5
13-Aug-20
Page 26 of 86
Do not
use any type of thread sealant on compression-type tube fittings.
Do not
open the valves on the transformer or the stainless steel tubing. This
is performed by GE-trained and certified personnel during the commissioning
phase to prevent air bubbles from entering the transformer.
8.3.3
Connection to oil supply valve
Oil is typically taken from a valve midway up on the transformer or from an active cooling
loop (see Section 8 for information on valve selection). Oil must be taken from a location
where the oil is well mixed and in the active flow of the transformer oil. The temperature
of the oil at this location should not exceed 100 °C or be lower than
−
10 °C.
Note: The
distance from the oil return valve should be at least 30 cm (12 in.).
These points must be observed when connecting to the oil supply valve:
▪
Locate the valve on the transformer chosen for the oil supply line. Identify the items
needed to adapt the oil supply valve to a ¼ in. female NPT fitting. Select fittings and
adaptors made from stainless steel, brass or black iron.
Do not
use galvanised steel, copper or plastic fittings as these materials can
negatively affect the gas concentrations in the sample line.
▪
All pipe fittings should be tight and all threaded pipe fittings tightly wrapped with
PTFE tape with a light coating of PTFE paste or other quality pipe thread sealant
applied over the taped male threads to prevent leaks. Both of these items are
included in the product installation kit.
Note: GE recommends two wraps of PTFE tape
or three wraps for large pipe fittings.
8.3.4
Connection to oil return valve
Oil is typically returned to a valve lower on the transformer
—
this can be the
transformer drain valve
. Note: The distance from the oil supply valve should be at least
30 cm (12 in.).
Do not
return the oil into a high pressure area on the transformer, such as a
cooling loop.
The following points must be observed when connecting to the oil return valve (see
Section 8 for information on valve selection):
▪
The return line to the transformer must be via the Return Assembly (see Figure 8-8 to
Figure 8-11). This assembly incorporates a check valve and port that facilitates
bleeding the system of air during the installation process. The bleed port must be
oriented up so that air can be drawn from the top. The assembly can be reconfigured
to fit the transformer valve and adaptor. This assembly must be adapted from a ¼ in.
female NPT fitting to the valve on the transformer.
