MA-005 - MINITRANS Installation Manual - Rev 3.1
29-Sep-15
Page 21 of 85
8.2.2
Oil Return
Oil is typically returned to a valve lower on the transformer, such as the transformer
drain valve.
Do not
return the oil to a location that leads directly to a critical location within
the transformer, such as a cooling loop designed for directed cooling.
Oil returning to the transformer must be via the “Return Assembly” provided in the
product installation kit. This assembly incorporates a check valve, a ball valve and a
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 it. The assembly can
be reconfigured to fit the transformer valve and adaptor, but must first be adapted
from a ¼ in. female NPT fitting.
If the oil return valve is located more than 1.82 m (6 ft) above the base of the
transformer, it is recommended that an additional ¼ in. ball valve be placed in the
oil return line within easy reach while standing, and in an easily accessible and
visible location. This valve can be used to conveniently shut off the oil return, if
required.
It is important to ensure that the configuration of the Return Assembly eliminates
any pre-existing air pockets. This is achieved by the use of a Tee on the return valve
with the bleed port facing upwards. To reduce the possibility of air pockets behind
the flange, the position of the ¼ in. NPT hole must be drilled near to the top of the
flange offset from the centre (see Figure 8—9).
Note: An optional manual oil sampling arrangement can be fitted to the oil inlet on the base of the
product. For more information, contact the GE Customer Service Centre.
8.3
Tubing
Stainless steel tubing is used to connect the product to the transformer. The amount of
tubing required is based on the location of the product in relation to the valves on the
transformer.
Stainless steel is the only material that should be used
– the use of any other
tubing material would invalidate the results of the analysis and void the
warranty of the product. (See Appendix D for a full description of the tubing.)
It is also recommended that each section of tubing between the transformer and the
product be installed as one continuous piece, and to use as few fittings as possible to
reduce restriction and minimise the risk of oil leaks.
