CN204188709U - Insulating oil dielectric loss detection system - Google Patents

Abstract

The utility model discloses a detection system for dielectric loss of insulating oil, which includes a frequency conversion power supply, an excitation transformer T, a reactor L, a detection circuit, a double-pole double-throw switch K1, and the double-pole double-throw switch K1 includes a linkage first action contact and the second movable contact, and the first static contact and the second static contact matched with the first movable contact, the third static contact and the fourth static contact matched with the second movable contact, Wherein, the two ends of the reactor L are respectively connected to the secondary winding of the excitation transformer T and the first movable contact, the second movable contact is connected to one end of the standard capacitor Cn, and the first static contact is connected to The third static contact is connected, the second static contact is grounded, and the fourth static contact is connected between the secondary winding of the excitation transformer T and the reactor L. The utility model realizes the switching of the test excitation transformer boost and the series resonance boost in the detection of insulating oil dielectric loss through the double-pole double-throw switch, so as to adapt to the measurement of capacitors of different samples.

Description

Insulating oil dielectric loss detection system

technical field

The utility model relates to the technical field of electric equipment maintenance, in particular to a dielectric loss detection system for insulating oil.

Background technique

Oil-filled equipment such as power transformers is one of the main equipment in the power system, and it is also one of the more expensive equipment. The economic losses caused by insulation failures are huge. Therefore, how to prevent potential failures of power transformers and ensure the reliable operation of the power grid , has been an important subject of long-term research on electric power at home and abroad. The quality of insulating oil is related to the safe and reliable operation of oil-filled equipment. At the same time, the problems and operating life of oil-filled equipment can be predicted based on insulating oil. The dielectric loss factor of insulating oil (tanδ) is an effective parameter that can judge the integrity of insulating oil samples. It can indicate the dirt and deterioration of the oil during operation or the treatment result of the oil is good or bad, so as to judge the insulation condition of oil-filled equipment , especially for distributed defects such as insulation damp and aging deterioration. The so-called dielectric loss factor is the complementary angle between the voltage and current angle on the dielectric. The dielectric loss factor is only related to the material characteristics, but has nothing to do with the size and volume of the material. The existing dielectric loss factor measurement methods mainly include bridge method, phase difference method and all-digital measurement method. The advantages of the bridge method are high reliability and accuracy, but the operation is complicated and cannot be applied in the field. The phase difference method test is relatively simple, and it is carried out in the form of a transformer, but it is greatly affected by the environment and the measurement accuracy is low. The all-digital measurement method can realize the full-digital filtering technology and the vector method test principle through the dielectric loss tester, and realize the detection through the capacitor voltage divider method. The measurement accuracy is high and the performance is stable. However, for different oil-filled equipment, the equivalent test The size of the sample capacitors is different, and the step-up method of this variable frequency power supply is single, and the dielectric loss measurement of the sample capacitors with different capacitances has different accuracy and poor versatility.

Utility model content

In view of the above deficiencies, the purpose of this utility model is to provide a dielectric loss detection system for insulating oil, which can realize the switching of test excitation transformer boost and series resonance boost in the detection of dielectric loss of insulating oil through a double-pole double-throw switch. Adapt to the measurement of capacitors of different samples.

For realizing above object, the technical scheme that the utility model takes is:

Insulating oil dielectric loss detection system, which includes a frequency conversion power supply, an excitation transformer T, a reactor L and a detection circuit, the output end of the frequency conversion power supply is connected to the primary winding side of the excitation transformer T, and the detection circuit includes a voltage divider C1 . One end is grounded, and the three detection input interfaces of the dielectric loss tester are electrically connected to the other end of the sample capacitor Cx, the other end of the standard capacitor Cn, and the voltage divider C1 and C2 respectively, and the dielectric loss of the insulating oil The detection system further includes a double-pole double-throw switch K1, the double-pole double-throw switch K1 includes a first movable contact and a second movable contact in linkage, and a first static contact and a second movable contact matched with the first movable contact. Two static contacts, a third static contact and a fourth static contact matched with the second movable contact, wherein the two ends of the reactor L are respectively connected to the secondary winding of the excitation transformer T and the first movable contact connected, the second moving contact is connected to one end of the standard capacitor Cn, the first static contact is connected to the third static contact, the second static contact is grounded, and the fourth static contact is connected to Between the secondary winding of the excitation transformer T and the reactor L.

Compared with the prior art, the utility model has the beneficial effect that: the utility model realizes the test excitation variable boost in the dielectric loss detection of insulating oil through the double-pole double-throw switch (the first moving contact cooperates with the second static contact , the second moving contact cooperates with the fourth static contact) and the switching of series resonance boost (the first moving contact cooperates with the first static contact, and the second movable contact cooperates with the third static contact), to It is suitable for small sample capacitors and large sample capacitors respectively (the capacitance value of the large and small sample capacitors is bounded by 5000pF), and has strong versatility.

Description of drawings

Fig. 1 is the circuit principle diagram of the insulating oil dielectric loss detection system of the utility model.

Detailed ways

The content of the present utility model will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Example

Please refer to Fig. 1, the insulating oil dielectric loss detection system, which includes a variable frequency power supply, an excitation transformer T, and a reactor L, a detection circuit and a double-pole double-throw switch, and the input end of the variable frequency power supply is connected to an AC power supply (such as 380V three phase power supply), its output end is connected to the primary winding side of excitation transformer T, the detection circuit includes voltage divider C1, C2, standard capacitor Cn and dielectric loss tester, and the end of voltage divider C1 and C2 is connected in series with the sample capacitor Cx And one end of the standard capacitor Cn is electrically connected, the other end of the voltage divider C1 and C2 connected in series is grounded, the three detection input interfaces of the dielectric loss tester are respectively connected to the other end of the sample capacitor Cx, the other end of the standard capacitor Cn and The voltage divider C1 and C2 are electrically connected, and the insulating oil dielectric loss detection system further includes a double-pole double-throw switch K1, and the double-pole double-throw switch K1 includes a first movable contact and a second movable contact linked together, and The first static contact and the second static contact matched with the first movable contact, the third static contact and the fourth static contact matched with the second movable contact, wherein, one end of the secondary winding of the excitation transformer T Ground, the other end is connected to the first moving contact through the reactor L, the second moving contact is connected to one end of the standard capacitor Cn, the first static contact is connected to the third static contact, the second static contact is grounded, and the second static contact is connected to one end of the standard capacitor Cn. The four static contacts are connected between the secondary winding of the exciting transformer T and the reactor L.

When in use, for the sample capacitor with a small capacitance (less than 5000pF), the method of test excitation transformer step-up (that is, shunt reactor) is used. At this time, the first moving contact is connected to the second static contact, The second moving contact is connected to the fourth static contact, the reactor L, the excitation transformer T and the detection circuit are connected in parallel with each other, and the excitation transformer is boosted to provide power to the test capacitor, which can realize automatic double-conversion anti-interference and measure the effect optimal. For the sample capacitor with a large capacitance (greater than 5000pF), the series resonance boost method is adopted. At this time, the first moving contact is connected to the first static contact, and the second moving contact is connected to the third static contact. Point connection, the reactor L and the detection circuit form a series structure connected to the secondary winding of the excitation transformer T. Series resonance has a natural advantage in measuring large capacitors, only large capacitors can resonate to lower frequencies.

The above detailed description is a specific description of the feasible embodiment of the utility model. This embodiment is not used to limit the patent scope of the utility model. Any equivalent implementation or change that does not deviate from the utility model shall be included in this case within the scope of the patent.

Claims (1)

1. Insulating oil dielectric loss detection system, which includes a variable frequency power supply, an excitation transformer T, and a reactor L and a detection circuit, the output end of the variable frequency power supply is connected to the primary winding side of the excitation transformer T, and the detection circuit includes a voltage divider C1, C2, standard capacitor Cn and dielectric loss tester, one end of the voltage divider C1 and C2 is connected in series with the test capacitor Cx and one end of the standard capacitor Cn, and the voltage divider C1 and C2 are connected in series The other end of the dielectric loss tester is grounded, and the three detection input interfaces of the dielectric loss tester are electrically connected to the other end of the sample capacitor Cx, the other end of the standard capacitor Cn, and the voltage divider C1 and C2 respectively. It is characterized in that, The insulating oil dielectric loss detection system further includes a double-pole double-throw switch K1, and the double-pole double-throw switch K1 includes a linked first movable contact and a second movable contact, and a second movable contact matched with the first movable contact. A static contact and a second static contact, a third static contact and a fourth static contact matched with the second movable contact, wherein the two ends of the reactor L are respectively connected to the secondary winding of the excitation transformer T and the first movable contact, the second movable contact is connected to one end of the standard capacitor Cn, the first static contact is connected to the third static contact, the second static contact is grounded, and the first static contact is connected to the ground. The four static contacts are connected between the secondary winding of the exciting transformer T and the reactor L.