Morgan Schaffer Calisto - Page 34

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Calisto/Calisto 2 requires two oil valves from the transformer. Typically the top oil fill valve and the
bottom main drain valves are used. The preferred method is to draw oil from the top fill valve and
return the oil through the bottom main drain valve. This can only be done if the top oil fill valve is
below the top oil level. If the top oil valve is above the top oil level it will be necessary to draw oil
from the bottom main drain valve and return it through the top oil fill valve. Drawing oil from the
bottom main drain valve can pose some problems if there is an excessive amount of sludge from oil
decomposition in the bottom of the transformer. Also, condensed water may accumulate at the
bottom of very wet transformers.
Here are some suggestions for determining whether the top oil valve is below the top oil level:
 Contact the transformer manufacturer.
 Contact the responsible party within your organization.
 Review the Outline drawings of the transformer and look for notes or review the instruction
book supplied with the transformer.
 Some transformers have a conservator tank. A conservator tank is a large cylindrical or
rectangular tank that sits above the transformer main tank. A pipe connects the conservator
tank to the main transformer tank. If this is the case, the top oil valve on the main tank will
be below the top oil level.
 Compare the location of the oil level gauge to the location of the top oil fill valve. If the
location of the oil level gauge is above the location of the top oil fill valve, most likely the
top oil fill valve is below the top oil level. If the top oil valve is higher than the location of
the oil level gauge, most likely the top oil fill valve is NOT below the top oil level.
 Review the small print on the transformer nameplate. Often there is a statement indicating
that the top oil level is X below the highest manhole cover on the top of the transformer.
Compare this measurement to the location of the top oil fill valve.
Refer to Figure 1 and Figure 2 to view the oil inlet and outlet ports of the Calisto/Calisto 2 monitor.