A way to assess the circumstance of the power transformer with an ISA testing system. There are various checks required to make the performance of the transformer seamless.
Common forms of exams are accomplished using the manufacturer before dispatching the transformer: routine tests and type tests.
Routine tests are made to affirm the operational overall performance of the individual unit in a manufacturing lot and they are executed on each unit synthetic, even as type tests must follow designated requirements no longer covered by way of recurring assessments: temperature upward pushes take a look at (IEC 60076-2) and dielectric kind tests (IEC 60076-three).
Further, some other checks also are finished by way of the customer at the website earlier than commissioning and also periodically on a normal & emergency basis all through its lifestyles. Periodic tests of the CHINT Power Transformer help you decide the condition of your asset and pick out the right corrective measures to make sure reliable operating lifestyles and expand the lifestyles expectancy of your energy transformer.
1. Winding resistance test
We carry out winding resistance checks to assess possible harm in windings or contact troubles. There are two common methods of testing: static winding resistance check and dynamic winding resistance test. Static resistance measurements are accomplished at the transformer without running the oltc during the size, while dynamic resistance measurements are resistance measurements regarding oltc operation in the course of the test.
The distinction between the measured value and the nominal value ought to be much less than 2 % – 3 %. Remember the fact that although it is the first mentioned test, we often carry out this checklist, and then the transformer needs to be demagnetized.
2. Turn ratio test
Turn ratio is one of the maximum basic checks at the chint power transformer. It identifies if there are any shorted turns and/or any open turns in the HV winding, presents information on insulation faults between the turns, and helps perceive the transformer vector group.
The turn ratio (n) may be defined as “the no-load voltage ratio” among two windings of a transformer. Please continually bear in mind to generate on the primary aspect and measure at the secondary aspect, in any other case high voltage at the number one aspect might damage the measurement enter. Consistent with IEC 60076-1 and IEEE c57.152, the measured values need to now not deviate extra than 0.5 % from the nominal ratio.
3. Quick circuit impedance check
Quick circuit impedance is the regular terminal voltage at the primary facet required to circulate full load contemporary beneath quick circuit conditions at the secondary side.
4. Frequency response to stray losses
Frequency reaction to stray losses is essentially the fast circuit impedance test but completed in distinct frequencies. Frsl is a quick circuit impedance test. However, the test at variable frequency i.e. 15hz to 500hz.
5. No-load modern test
Which will perform the check, the second facet of the transformer needs to be opened. Then the voltage is generated on the primary aspect (for every phase one at a time). While we make one of these setups we can see what are the losses in the core and in doing so we can find if we have some of those troubles:
- unusual core grounds
- winding faults: shorts, open circuits
- on-load tap changer problems
- production defects
6. Tan delta test
This check is used to measure the fine of chint power transformer insulation. In the transformer, there are a few insulations – HV side – lv aspect, hv aspect – gnd, lv aspect – and. What we surely do is we generate up to 12 kv (the usage of td 5000) and then we measure the resistive ir and the capacitive ic modern-day due to this voltage.
7. Sweep frequency response assessment
Sfra is one of the reliable and touchy strategies to assess the mechanical and electrical deformation (geometrical movement) in the transformer. The test is performed to attain the switch function of the transformer over a huge range of frequencies.
Sfra can stumble on core deformation, center earth removed, extra core earth, magnetized core, collapsed winding, radial deformation, raised/reduced winding, unclamped winding, shorted turns, an open circuit is broken conductor strands, and unclamped core.
8. Demagnetizer
This is not a check but an interest that needs to be executed on the way to “reset” the transformer after the winding resistance test. What we do right here is we follow a DC with change polarity to the winding, which allows you to remove the residual magnetism from the core.