Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F27/00—Details of transformers or inductances, in general
  • H01F27/08—Cooling; Ventilating
  • H01F27/10—Liquid cooling
  • H01F27/12—Oil cooling

Definitions

• the invention relates to a method for controlling devices for cooling an oil-filled power transformer as a function of its oil or winding temperature.
• Oil-filled power transformers are internationally characterized by their design and type of cooling with a 4-letter code.
• the first two letters refer to the type of cooling of the transformer itself; for this there is the abbreviation ON for "Oil Natural”, OF for “Oil Forced”, OP for “Oil Forced”, but with an oil cooling system with axial pump, OD for "Oil Directed”, as well as GF for "Gas Forced” (for transformers with SF 6 cooling) as a special design
• the following two letters indicate the respective type of cooling medium, for which there is AN for "Air Natural”, AF for "Air Forced”, WF for "Water Forced”.
• transformers By combining different types of cooling of transformers as well as different types of cooling medium therefore exist a variety of types of transformers, which can be represented by the illustrated coding.
• an oil-filled power transformer usually has several cooling stages, which can be based on different types of cooling or types of cooling medium.
• the object of the invention is to provide a method that decreases the user this complex activities.
• This object is achieved by a method having the features of the first claim.
• this method it is only necessary to identify the type and types of cooling of the respective power transformer and to specify the above-explained letter-coded characterization of the respective type of cooling of the transformer and the cooling medium in its respective cooling stages.
• These few necessary details about the power transformer are known to the user; They are included on the type plate and can be easily, easily and without transmission errors in a corresponding control unit.
• the method according to the invention makes use of the circumstance that the calculation rules to be used for calculating the specific 01 and winding temperatures, including the respective variables and parameters, are clearly defined in the cited IEC and therefore mandatory for the user to use. Therefore, these values are already stored non-volatile in the factory so that practically only one parameter has to be entered manually: The 4-letter coding for each existing cooling stage of the corresponding power transformer.
• the offered by the Applicant electronic control unit TAPCON ® is the 260th
• Figure 1 shows the method according to the invention in a schematic representation of all sequentially proceeding process steps
• Figure 2 is an expanded view of important steps in the process and the
• This calculation is made in accordance with the specific requirements of IEC 354 applicable to the particular transformer. For this calculation, the top oil temperature, the load current, the load factor - that is the quotient of the load current and the rated current - and other specific ones provided by the IEC Parameter used.
• the term "separate comparison" means that it is first checked whether the calculated value ⁇ exceeds the limit value S 1 for the first cooling stage, if this is the case the first cooling stage is activated and it is checked whether the calculated value ⁇ is so great that it also exceeds the threshold value ⁇ 2 of the second cooling stage, in which case the second cooling stage is also activated, and this comparison is continued in an analogous manner for any further cooling stages.
• the control unit used for carrying out the method in this example has four switching contacts S1 ... S4; It is for a transformer with up to four different ones
• Cooling stages 1 ... 4 usable. If fewer cooling stages are available for the respective transformer, the remaining contacts remain unused.
• Cooling level 0, d. H. Normal operation is usually always called ONAN.
• Cooling stages with the same type of cooling are indicated in ascending order with an index that corresponds to the number
• Each cooling stage is associated with characteristic parameters, the gradient gr, the winding exponent y and the winding time constant tau, which depend on the type of transformer and the
• Cooling stage 1 ... n - here as a percentage switching point in degrees Celsius above the respectively calculated
• Control unit existing contacts S1 ... S4 are occupied here.
• Switching contact 5 when exceeding the limit value ⁇ 4 for the last cooling stage 4 triggers a warning signal that signals that the regular cooling stages are obviously not able to
• Another switching contact 6 is triggered, although the limit value for this warning message is still significantly exceeded; then the entire transformer is shut down to prevent damage.
• the cooling stages 1... 3 are designed in the ONAF design and, as explained above, are therefore supplemented by an index 1.
• the last cooling stage 4 in this example is of the OPAF type.
• both the calculated oil temperature and the calculated winding temperature can be used as the comparison variable in the method according to the invention, which is why here consistently both types of calculated temperature are provided with the same reference symbol ⁇ . Differences arise, however, in terms of responsiveness, since the winding temperature changes much faster than the oil temperature, which follows with a certain inertia of this.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Housings And Mounting Of Transformers (AREA)
• Protection Of Transformers (AREA)
• Transformer Cooling (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=35597791

Family Applications (1)

Country Status (6)

Cited By (1)

Citations (3)

• 2005
  • 2005-11-22 DE DE502005005836T patent/DE502005005836D1/de active Active
  • 2005-11-22 EP EP05815353A patent/EP1859331B1/de not_active Not-in-force
  • 2005-11-22 ES ES05815353T patent/ES2314737T3/es active Active
  • 2005-11-22 AT AT05815353T patent/ATE412935T1/de not_active IP Right Cessation
  • 2005-11-22 WO PCT/EP2005/012455 patent/WO2006097142A1/de not_active Application Discontinuation
  • 2005-11-22 PL PL05815353T patent/PL1859331T3/pl unknown

Patent Citations (3)

Non-Patent Citations (2)

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