Introduction to transformer DC resistance and tap changer comprehensive tester
The DC resistance test of transformer winding is an indispensable test item for transformers after handover, overhaul, and change of tap-changerAt the same time, the on-load tap-changer is the only moving part connected with the transformer circuit, so the detection of the on-load tap-changer has attracted more and more attention. In the "Regulations for Handover and Preventive Test of Power Equipment", it is required to check the operation sequence of on-load tap-changers, measure the switching time, etc.
The traditional test method for both test projects is a split test, i.e. a direct resistance test and an on-load tap-changer tester are required. Because it is a two-sided instrument, each instrument is equipped with a special test line, which requires separate wiring and testing, which leads to a greatly reduced work efficiency.
In addition, for the transformer DC resistance test project, with the development of the power grid in recent years and the continuous improvement of transformer technology, there are many phenomena of excessive evaluation. The in-depth study of this problem finds that the main reason for this phenomenon is that due to the inaccuracy of the oil temperature of the upper layer of the transformer in the field, there is a large error in the uniform conversion of the DC resistance value to 75 evaluation.
In order to solve the above problems, our company has developed and produced a comprehensive tester for transformer DC resistance and on-load tap-changer, which can carry out two tests with only one-time wiring: direct resistance test and on-load tap-changer test. In addition, the wireless temperature measurement technology can be used to monitor the internal oil temperature of the transformer in real time, so that the DC resistance value can be converted to 75 evaluation standards more accurately and reliably.
Performance characteristics of transformer DC resistance and tap-changer comprehensive tester
1. At the same time, it has the functions of direct resistance test and on-load tap changer test, one-time wiring, and completes two kinds of tests, which is simple and convenient.
2. For the winding test of the star connection with the neutral point lead-out wire, the instrument can take the three-phase simultaneous measurement method to test the three-phase DC resistance, saving the test time. In addition, the data of the A0 phase is tested first, and then the data of the three phases is tested at the same time, which solves the problem that the resistance of the neutral point lead wire cannot be tested during the simultaneous test of the three phases, and makes the test data closer to the single-phase test value.
3 For the winding test of Y type and type, the instrument can carry out the three-phase automatic test and calculate the three-phase unbalance rate.
4. The instrument comes with a wireless temperature measurement function, which can monitor the internal oil temperature of the transformer in real time.
5. It has a variety of protection functions such as back electromotive force protection, wire break protection, etc.
6. The instrument adopts the operation mode of button and shuttle, which is flexible and simple to operate, especially for the operation optimization of the on-load waveform analysis function, which greatly improves the user's efficiency and operability.
7. It has local storage and USB disk storage, in which the local machine can store 200 on-load test results and 200 direct resistance test results, and the local storage can be transferred to the USB diskWhen the USB disk is stored, the transition waveform and other information of the on-load test results are directly saved in BMP** format, and the direct resistance test results are directly saved in Word format, which is convenient for users to print and view directly on the computer.
8 No power down, clock and date display.
9 Thermal printer printing function, fast and silent.
10. The human-computer interaction interface is more friendly.
11. Small size, light weight, easy to carry and use.
Technical indicators of transformer DC resistance and tap changer comprehensive tester
1 On-load test.
1.1. On-load test output current: 10a、0.5A two gears are optional.
1.2. Transition resistance measurement range: 10a file 01～20ω 0.5a file 50～40ω
1.3. Transition resistance measurement accuracy: (reading 5% + 5 words) Resolution: 001ω
1.4 Transition time measurement range: 1 250ms
1.5. Transition time measurement accuracy: 1ms resolution: 01ms
1.6. Sampling frequency: 10k
2. Direct resistance test.
2.1 Range: 10A 1000mω～1ω
1 a 100.0mω～20ω
5 a 10.00mω～4ω
5a + 5a 10.00mω～1ω
1a + 1a 100.0mω～5ω
2.2 Accuracy: (Reading: 0.)2% + 2 words).
2.3 Maximum resolution: 001uω
3. Power supply: AC220V 10%, 50 60Hz
4 Operating temperature: -10-50 Relative humidity: 90%, no condensation.