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8.1.4 Cooling loop valves
The product should only be supplied with oil from a cooling loop valve if there are no
other valves available.
supply valve must be located on the high-pressure side of the oil pump.
Do not
and that there are no other alternative valves in which to connect the
product.
8.2
Supply & Return Valves
All transformers have different valve configurations. The transformer supply and return
valves should be assessed for durability to ensure that a reliable connection can be
made. The valve size should measure at least 15 mm (½ in.) in diameter. These valves
will need to be adapted to ¼ in. female NPT fittings to properly fit the ¼ in. NPT male
fittings on the product. When choosing how to prepare the oil supply and return valves,
consider these points:
Hot surfaces present on oil pipes and risk of contact with mineral oil. Use
suitable PPE.
8.2.1 Oil supply
▪
Oil is typically taken from a valve midway up on the transformer or from an active
cooling loop.
necessary to ensure that the oil is taken from a location where the oil is well mixed
and in the active flow of transformer oil. The oil temperature at this location should
not exceed 100 °C or be lower than −10 °C.
▪
The distance between the oil supply valve and oil return valve should be at least 30
cm (12 in.) to prevent mixing of the de-gassed oil with the transformer oil being
sampled.
▪
Fittings must be provided to adapt the oil supply valve to a ¼ in. female NPT fitting
using fittings and adaptors made from stainless steel, brass or black iron.
Do not
negatively affect the gas concentrations in the sample line.
▪
If the oil supply 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
supply 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 supply, if required.
MA-005 - Minitrans Installation Manual - Rev 4.5
Note: If oil must be taken from an oil-forced cooling loop, the oil
return oil to the cooling loop unless the cooling is not directed flow
Note: Oil should not be taken from a forced oil cooling loop.
use galvanised steel, copper or plastic fittings as these materials can
It is
13-Aug-20
Page 22 of 86
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