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8.2.2 Oil return
▪
Oil is typically returned to a valve lower on the transformer, such as the transformer
drain valve.
Do not
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
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.
Consider these points when choosing where to route the tubing and estimating how
much tubing is required:
▪
The route must not interfere with the regular maintenance of the transformer. The
tubing shall not be routed so that it could be stepped on, tripped over or damaged by
activities near the transformer.
▪
The route shall be selected to allow the tubing to be secured to existing structures. It
is important that the tubing be adequately secured to the structure of the
transformer or ancillary structure with appropriate mounting hardware and
fasteners. (Swagelok or Ham-Let offer several options for mounting and securing
tubing.)
MA-005 - Minitrans Installation Manual - Rev 4.5
return the oil to a location that leads directly to a critical location
– the use of any
13-Aug-20
Page 23 of 86
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