Systems and methods for removing moisture from a power transformer

A system for removing moisture from a power transformer, the system comprising:

• a power transformer electrically connected to an electric grid, the power transformer having paper insulation and oil positioned therein;
• and
• a moisture removal system connected to the power transformer at an input channel and an output channel, the moisture removal system comprising:
• a pump positioned so as to move oil from the power transformer into and through the moisture removal system via the input channel,
• one or more incoming oil moisture and temperature sensors to detect a moisture level and a temperature of oil when pumped from the power transformer into the moisture removal system via the input channel,
• one or more processors to receive the moisture level and the temperature from the one or more incoming oil moisture and temperature sensors, the one or more processors configured to determine, based on the moisture level and the temperature, an estimated paper moisture value of the paper insulation, and also configured to compare the estimated paper moisture value to a predetermined target paper moisture value, and
• an overdry prevention bypass valve configured in a first position so as to divert oil to the output channel without drying when the processor determines that the estimated paper moisture value is equal to or less than the predetermined target paper moisture value, and in a second position so as to channel oil through one or more drying cylinders so as to remove moisture from the oil when the one or more processors determines that the estimated paper moisture value exceeds the predetermined target paper moisture value.

A system to remove moisture from a power transformer, the system comprising:

• a power transformer having paper insulation and oil positioned therein;
• and
• a moisture removal system connected to the power transformer and positioned to move the oil from and to the power transformer, the moisture removal system including:
• a pump positioned to move oil from the power transformer into and through the moisture removal system from the power transformer and return to the power transformer therefrom,
• an internal moisture removal conduit to receive the oil and return oil thereto, the internal moisture removal conduit including a first internal conduit path and a second internal conduit path,
• one or more drying devices fluidly connected to the first internal conduit path to reduce moisture content of the oil when flowing therethrough,
• one or more oil moisture and temperature sensors positioned to detect moisture level and temperature of the oil when pumped from the power transformer into the moisture removal system,
• a controller positioned to receive the detected moisture level and temperature from the one or more oil moisture and temperature sensors, the controller being responsive to the detected moisture level and temperature to determine an estimated paper moisture value of the paper insulation and to compare the determined estimated paper moisture value to a preselected target paper moisture value, and
• an overdry prevention bypass valve responsive to the controller to direct the flow of the oil between the first internal conduit path and the second internal conduit path and positioned so as to allow the oil to circulate through the first internal conduit path to the one or more drying devices to reduce moisture content in the oil and to the output channel therefrom and to divert oil through the second internal conduit path directly to the output channel.

A method to remove moisture from a power transformer having oil and paper operationally associated therewith, the method comprising:

• pumping oil from the power transformer into a moisture removal system via an input channel;
• detecting a moisture level and a temperature of the incoming oil;
• determining, via one or more processors, an estimated paper moisture value of the paper insulation associated with the power transformer based at least in part on the detected moisture level and the temperature of the incoming oil;
• comparing, via the one or more processors, the estimated paper moisture value to a predetermined target paper moisture value;
• and
• operating, via the one or more processor, an overdry prevention bypass valve, the overdry prevention bypass valve configured to channel the incoming oil through one or more drying devices positioned to remove moisture from the oil when the estimated paper moisture value is determined to be greater than the predetermined target paper moisture value, and configured to divert the incoming oil to bypass the one or more drying devices when the estimated paper moisture value is determined to be less than or equal to the predetermined target paper moisture value.