I am working on a Tsurumi vancs 50PLS2.15S pump (Aquascapes 3-PL). The pump was used as pond waterfall pump and was tripping a ground fault. It had no mechanical issues and ran great when pulled into an outlet without a ground fault.

It had a line to ground impedance of 150 kohms. I removed black the plastic cap where the electrical cable enters the pump and removed the oil, which had a few rust particles. Afterwards the line to ground impedance was > 20Mohms without oil. It appears as though there is a separate oil which covered the electrical section of the pump, as quite a bit came out. I also drained the lubricating oil from oil drain screw which had a separate section of oil. About 4 oz of sludgy oil came out. According to the Aquascapes manual there should 5.1 oz, so this is close.

For this pump is there supposed to be a separate section of oil around electrical section? How much oil should be around the motor and electrical section and how can it be refilled? Is it also white mineral oil iso vp 32 which is in the drive section of the pump? Should I use dielectric oil for transformer/sump pumps such as U197-8a?

Does anyone have any technical drawings or additional information on this pump? Thanks for any assistance.