Created: 15-11-21
Last Login: 15-11-21
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Best Ways to Test Transformer Oil
"What is the best transformer oil testing equipment?"
Several variables must be considered in order to answer this question, including your budget, the volume of samples to be tested and the need for real-time continuous monitoring.
Cost is generally the first consideration. Like most business decisions, a cost/benefit analysis should be conducted to determine whether testing is a valid expense. Sadly, in many cases, once the cost of testing or testing equipment is calculated, the answer typically is, “We can’t afford that now.” The idea often is then put on the back burner where it eventually withers and dies.
However, if you compare the cost of testing or testing equipment to the cost of a replacement transformer, labor to remove and reinstall, and most importantly the cost of downtime, how can you afford not to perform testing?
The next consideration should be whether the volume of samples is sufficient to justify the cost of onsite testing equipment and personnel. In most cases, the sample volume is not enough to warrant this expense. In these cases, a third-party lab must be selected that can perform the following tests for in-service transformer oils: interfacial tension (ASTM D971), acid number (ASTM D664), dielectric breakdown voltage (ASTM D877 or D1816), Karl Fischer water (ASTM D1533), oxidation inhibitor (ASTM D4768 or D2668) and dissolved gas analysis (ASTM D3612).
In addition, the following tests should be conducted upon receipt: liquid power factor (ASTM D924), specific resistance (ASTM D1169), corrosive sulfur (ASTM D1275), gassing tendency (ASTM D2300), oxidation stability (ASTM D2440) and particle count (ASTM D6786).
If the decision is made to perform testing in-house, many of the necessary tests may be outside the standard capabilities of the "lab-in-a-box" equipment currently on the market. This will require purchasing multiple pieces of equipment, which can be several thousands of dollars per piece. Unless the volume of samples is significant, there is no initial cost savings to purchasing onsite equipment. Nevertheless, the benefit of having instant test results allowing for the identification and correction of an impending equipment failure could well justify the cost as indicated above in the form of repair work and downtime.
In regard to real-time condition monitoring, as technology advances and test equipment becomes less expensive, it may be well worth the investment. Several companies now offer monitoring equipment for continuous dissolved gas analysis as well as instruments to measure electrical conductivity, dielectric constant, oil temperature, etc. Many of these have the option of transmitting data to a central location via Wi-Fi, adding the convenience of monitoring a transformer’s condition from the control station. This could potentially reduce or eliminate the need to periodically sample and test the oil, as you would allow the system to monitor the oil and test only when an exception condition was indicated.
Keep in mind that there is no "one-size-fits-all" approach. The best equipment will be whatever provides the most accurate results, is most affordable and, most importantly, will actually be used. When making these decisions, be sure to take into account the cost of the downtime to be incurred if you suffer a catastrophic failure.
What is Flash Point of transformer oil?
At which minimum temperature the transformer oil gives of vapor to ignite in the air is called the flash point of transformer oil. Commonly the flash point of transformer oil/ insulating oil is 140 degree Celsius. Flashpoint is the physical parameter of transformer oil. Flashpoint test of transformer oil indicates the flammability of the substance or the organic compound.
Flashpoint test of transformer oil is a low-cost test and popular test of insulating oil and can use transformer oil flash point tester. The oil sparkles after the mixing of vapor with oxygen in the air. The vapor pressure of oil normally in flash point is 3-5 mm Hg. When a small amount of flame is applied to the oil the mixture of vapor will burn for temporary and then it will get rid of automatically when the point temperature has been reached. If we continue the heating process for a long time or more than the flash point (50-70 degree Celsius) then the oil will be reached at the fire point.
What is a transformer?
Transformers are used to change an AC voltage, for example by stepping it up or stepping it down. They also play an insulating role. In this latter role, they protect the users of electric equipment by isolating the input and output sides of the power supply circuit so that electricity on the input side cannot flow directly to the output side. We can use transformer tester to finish these operations.
Examples that are familiar to most people include the small transformers that people use during overseas travel and the bucket-shaped transformers that you can see mounted on utility poles.
Transformers convert electricity to an easy-to-use voltage based on the necessary load at the facility in question, from high voltage to low voltage. You may be wondering, “Why not just transmit electricity at an easy-to-use voltage in the first place?”
However, transmitting electricity via power lines at low voltages causes substantial transmission losses. Power plants use high voltages to reduce current while transmitting electricity in order to limit transmission losses.
CT/PT ANALYZER
CT PT Analyzer is an all in one solution for testing all type of CT/PT as per IEC standards. It is an equipment with high ROI ( Return On Investment ) . Below features make CT/PT analyzer and ideal tool for CT/PT Manufacturer , Testing labs , Substations (Upto 765KV) , Power Plants etc.
Low Testing Time (Completes all test for CT/PT Winding & Cores in few min)
Simple connection (Simple one time connection)
Highest Accuracy (0.05% for turns ratio & winding resistance )
Portable & Light Weight ( < 15KG )
High Interference Rejection (Can be used in 220/400/765 KV Live Switchyards )
This compact 15kg unit with complete measurement function is capable of testing all types of current/potential transformer as per below test standards
CT PT TESTER
The CT PT tester can carry out testing work such as current transformer and voltage transformer excitation characteristics, ratio, polarity, secondary winding DC resistance, CT secondary circuit AC load, etc.
1, Use of DC method and low frequency method test current transformer excitation voltage below 80kV excitation characteristics, the speed is extremely fast.
2, Use of voltage and current method to test the current transformer (including the transformer bushing CT) ratio, polarity.
3, The built-in power supply has an output current way, used to check the integrity of the current transformer secondary circuit.
4, With current output function, the external booster output maximum current 200A (optional).
5, Test current transformer secondary winding DC resistance.
6, Test current transformer secondary circuit load.
How to use zinc oxide arrester tester
Many people who have been in contact with the zinc oxide arrester tester only know that this tester is used for electrical test and arrester testing, but the specific usage requirements and methods may not be well understood. Now the editor has compiled this article to give everyone a specific understanding of the zinc oxide arrester tester, so that everyone can use this instrument better and more conveniently to ensure the normal operation of the zinc oxide arrester.Under normal circumstances, a lightning arrester is an electrical appliance used to protect electrical equipment from high transient overvoltage hazards and to limit the freewheeling time and often limit the freewheeling amplitude. It is also another important equipment that is often used when communication cables are used to prevent lightning damage. The zinc oxide arrester tester mainly monitors the electrical performance of the arrester.
Glove Integrity Testing – Pressure decay Method: Performance Qualification
In recent years, Glove Integrity Testing has been profoundly discussed and numerous articles have been written on this topic. However, many doubts still remain within the industry due to the lack of norms and clear guidance available. In 2008 Annex 1 to EU Guidelines to Good Manufacturing Practice reiterated the importance of having glove integrity testing:
“25. Monitoring should be carried out routinely and should include frequent leak testing of the isolator and glove/sleeve system.”
Over the course of the past few years different industry specific associations have conducted statistical studies about the frequency in which this type of testing is performed in the pharma industry and the results indicated that the test is executed normally prior to each batch of a production run.
However as far as performance requirements the question is still open: which hole diameter should I be able to detect?
The theoretical answer would probably be 1μm (bacteria spores diameter), but the practical answer is much larger due to technological limitations at this time.
The methodologies of testing available today are many, but few of them may be automated and many times they are not suitable for the routine.
Moreover today it is difficult to find equipment to test the integrity of gloves that comes with performance qualification (PQ) and this is mainly due to the lack of test repeatability. Although there are many different methods available in the industry, the method used by the greatest portion of the users to test the integrity of the gloves is the Positive Pressure Decay method which follows the international standard ISO 14644-7 Annex E.5.
The ISO 14644 Part 7 doesn’t detail specific methodologies for the Positive Pressure Decay. In terms of acceptance criteria many different interpretations can be reached. The box below shows what the ISO norm states about the test procedure and the results.
As such, the equipment and the test can be easily validated while the specific glove and fixing mechanism (flange and counterflange, o-ring, etc.) is characterized in terms of “normal leakage” (Closed System curve). Before running the test, it is important that the integrity of the machine running the test is also verified and assured.
With the method described above a variety of hole diameters can be detected developing the correct test parameters.However the detection limits are primarily influenced by the precision of the adopted transmitters, statistics involved and time constraints.
Using this method with a calibrated hole of 100 μm a high level of reproducibility and a very, very low frequency of false positives has been observed. This means that an automatic gloves test machine may be easily validated. Lower detection limits may be achieved by the use of smaller calibrated hole sizes, but this practice will impact the reproducibility and the probability of false positives.