CT Tests – Ratio and Polarity In order to avoid increasing the winding temperature by the applied current, the measurement has to be completed in a short time and the measuring current has to be kept between 25%…100% of the rated current. The circuit connection shall be made as shown Figure 2 for loop resistance. During measurement, the current has to be at the value of IN or close to this value as far as possible. I am JE of Nagbhir sub station of 132/25 kv newly electrified section and testing started of current transformer when test CT ratio by injecting current in primary bushing of old CT which was 20 years old CT installed in circuit,after testing values not found according to ratio,100 amps inject and found in secondary terminal 3.9 amps please send me solution. Secondary resistance test is to verify the CT secondary winding resistance with specified one and no discontinuity in the winding. 1. Demonstration of UHF partial discharge location in a power transformer using time-of-flight techniques. These values are recorded and guaranteed to the customer and important for operational economy. In order to test instrument transformers to accuracy class 0.1, it has been previously necessary to carry out a complex on-site test, or sometimes to disassemble them completely and take them to a test laboratory for testing. Please supports, tHANKS FOr yoUR VAluaBLE InfO OVer tTHE yeARS MR. Edvard Csanyi……, sir i can’t download this article because download link is not available .plz help me. The same can be verified for other cores.
The short-circuit loss is a data which is also used in the heat test. You have disabled JavaScript. The voltmeter and ammeter must be connected as follows : Unless otherwise agreed, the HV winding shall be connected on principal tapping. Yes, I am a Electrical Engineer from SriLanka and I have been reading your valuable technical Articles for more than one year period and I have learned a lot from them and wish to add some articles in the near future. Verify nameplate ratings are in accordance with the approved drawings and specifications. The circuit connection shall be made as shown Figure 4. Very helpful for me, thanks and wish many more such articles. 2 incoming feeder from old substation supply permanent power to New Substation. Nice to know your background and engineering wisdom to the power systems. Tell us what you're thinking... we care about your opinion! The circuit connections shall be made as shown in Figure 4. Test Equipment Required 3. These values are influenced by temperature, so ambient temperature must be recorded during this test. The content is copyrighted to EEP and may not be reproduced on other websites. Please upgrade your browser or use another browser to view this page correctly. IEC 60044-1: Instrument transformers – current transformer. In cases where the power supply is not sufficient enough to supply the measurement circuit, compensation to meet the reactive power has to be made using capacitors. Class X CT: The obtained Vk should be greater than specified one; mag current should be less than specified one. Testing and diagnostics of power transformers Brochure, Maintenance Management of Protection Systems, Client/Server Communication (MMS) in IEC 61850 Environments. Magnetization Curve test is to confirm the magnetisation characteristics of CT with nameplate specification. If these two readings are equal, no correction shall be applied on the measurement of no-load loss. C57.113. With our testing system, you can use a single device to determine all of these parameters in an easy way. Measure secondary current at all points of CT circuits.
75°C ) stated in the standards and evaluated. Verify tightness of accessible bolted electrical connections by calibrated torque-wrench method. This test is performed to ensure the expected overall insulation strength of the transformer. Get access to premium HV/MV/LV technical articles, electrical engineering guides, research studies and much more! Secondary current should only be observed at respective phases and no current on neutral during Phase to phase injection. Resource: Testing and Commissioning of Electrical Equipment – Schneider Electric Service Dpt. The wave shape shall be as nearly as possible of the sine-wave and the primary windings shall be open. Winding resistance measurement shall be performed when the windings are at ambient temperature without supply for a time long enough to achieve this condition. 52Buxton St Doornfontein Johannesburg South Africa, New version of this literature is very useful https://library.e.abb.com/public/c1256b3c00492da6852570f8006d6175/1LAB000074_Testbook_intro.pdf.