Pre commissioning test of power transformer

Several methods for substation commissioning substations provide utilities and developers with ways to effectively maintain project schedules. It is widely known in many industries that testing the entire system, as installed, is the best way to ensure performance and system availability.

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Changing the tap settings on a transformer is a common way to provide conditions for testing. Considerations when using this method for transformer commissioning include:. When a new substation is constructed or a substation is upgraded, it must be tested before going live. The substation commissioning process involves turning on the facility operations, determining what works, identifying any issues and then fixing problems prior to the operation going on-line.

Following established standards and proven processes helps ensure a successful utility substation commissioning. It will explain how successful commissioning can lead to greater control, more efficient operations and lower costs.

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pre commissioning test of power transformer

Do you have a question? Connect with one of our experts. Please fill out the form and a member of our team will contact you within one business day.Transformer is the most important equipment in the electrical power transmission and distribution system.

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In order to ensure availability of uninterrupted power supply, it is essential that the condition of trans-former is continuously monitored during service as failure of transformer would result in interruption of power supply resulting loss of industrial production and inconvenience to customers on large scale. On receipt of transformer at site, it is essential to verify the technical suitability for the application and check the healthiness of the transformer before energizing by connecting to the power supply system and loading the same.

This course aims in providing participants clear under-standing of the basic constructional features of power transformers, various processes during manufacturing, various fittings and accessories, type tests and routine tests in manufacturers works, pre dispatch precautions, Non destructive diagnostic measurements to access present condition of transformers, installation at site, pre-commissioning testing including diagnostic tests and commissioning of the trans-former and preventive maintenance practices.

The course will also definitely be beneficial for the all the other department people concerned with the plant operations, production, maintenance and safety. It could be also useful for the procurement and quality personnel. Transformer Polarity, Terminal Markings, and Connections. Online Condition Monitoring of Transformers.

Online Monitoring of Bushings and Lightning Arrestors. A variety of methodologies will be used during the course that includes:. International AI Driving…. Abu Dhabi Polymers Company…. Abu Dhabi Company for…. Abu Dhabi Distribution…. Abu Dhabi Chamber of…. Abu Dhabi Commercial…. Abu Dhabi Food Control…. Abu Dhabi Gas Industries…. Abu Dhabi Gas Liquefaction…. Abu Dhabi Health Services…. Abu Dhabi Marine Operating…. Abu Dhabi National Exhibitions….

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Abu Dhabi National Oil…. Abu Dhabi Police. Abu Dhabi Sewerage Services…. Abu Dhabi Transmission…. Abu Dhabi City Municipality. Al Ain Distribution….You can find below a comprehensive switchgear testing and commissioning procedure. It is necessary that all testing tools are available before starting the work.

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Therefore at least following tools shall be arranged before starting the electrical testing job. All workers to comply the safety requirements such as safety shoes, safety helmet, safety glasses, fluorescent vest, and safety gloves to ensure maximum ability of safe work.

PTW should be signed by all parties with valid dates and times related to the specific activity. Check the cable installation and ensure the following are in accordance with the approved shop drawings. The above said is repeated for other phases and other breakers as applicable.

Then dividing the value of the primary voltage by the secondary voltage checks the ratio of the VT. Relay Testing. While doing the HV test the steps to be followed are as below:. Primary injection is done by applying current in primary of the CT and measuring the current up to the last point of the secondary circuit by making all the CT circuits through. This test is proving the secondary circuit of CTs is proper. I believe that an electrical engineer has all the measuring tools needed to test our switchgear.

Sharing is caring:. Like this: Like LoadingThe pre-commissioning tests need to be carefully programmed so that they take place in a logical and efficient order, in order that no equipment is disturbed again during subsequent tests. Before starting the tests, it is essential to ensure that the assembly of the particular item being tested has been completed and checked. The most important pre-commissioning tests and in-service checks of protection system can be summarized as follows:.

In addition, the list of the tests to be carried out should be arranged in a chronological order together with any precautions that need to be taken into account.

Some of the more usual tests are briefly described below. This test should be carried out with the aid of a V insulation resistance meter.

It is difficult to be precise as to the value of resistance that should be obtained. The climate can affect the results — a humid day tends to give lower values, whereas on a dry day much higher values may be obtained. These tests are intended to reproduce the operating conditions for each relay and are limited solely to the protection as such, so that it is important to read and understand the relay instruction manual application, operation, technical characteristics, installation and maintenance.

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The actual tests carried out on the relays depend largely on the type of relay. Secondary injection tests are required to ensure that the protective relay equipment is operating in accordance with its preset settings. Relay inputs and outputs must be disconnected prior to perform these tests. The test equipment supplies the relay with current and voltage inputs that correspond to different faults and different operating situations.

Pick-up values are reached by gradually changing the magnitudes of these inputs while simultaneously measuring the relay operating time. If the curves and characteristics of a relay are to be tested at many points or angles, it is convenient to use test equipment that can conduct a test automatically.

Commissioning / routine / diagnostic

Modern protective relay test equipment has the option of performing automatic tests aided by software programs, for which the testing process is much faster and more precise. Figure 1 shows a typical layout of a protective relay test equipment.

This equipment is able to provide current and voltage injection as well as phase shift when testing directional protection. For example, a typical pro forma for overcurrent relay tests, as shown in Figure 2 below, could have the following information recorded:. It is important to note that the tests referred to beforehand correspond to steady-state conditions, and the equipment to carry them out is rather conventional.

As a consequence of technological developments, more sophisticated equipment is now available to undertake tests using signals very similar to those that exist during fault conditions.

Since relays are required to respond to the transient conditions of disturbed power systemstheir real response can be assessed by simulating the signals that go to the relays under such conditions. Several manufacturers offer equipment to carry out dynamic-state and transient simulation tests.

A dynamic- state test is one in which phasor test quantities representing multiple power system conditions are synchronously switched between states. Power system characteristics, such as high frequency and DC decrement, are not, however, represented in this test.

A transient simulation test signal can represent in frequency content, magnitude and duration, the actual input signals received by a relay during power system disturbances. Before commissioning a protection scheme, it is recommended that the following features of current transformers are tested:.

When CTs are connected in order that a fault on a breaker is covered by both protection zones, the overlap connections should be carefully checked.

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This should be carried out by a visual inspection. If this is not possible, or difficult, a continuity test between the appropriate relay and the secondary terminals of the appropriate CT should be carried out.

There are often several combinations of CTs in the same bushing and it is important to be sure that the CTs are correctly connected to their respective protection. Sometimes all the CTs have the same ratio but much different characteristicsor the ratios are different but the CTs are located close together, which can cause confusion. Each CT should be tested individually in order to verify that the polarity marked on the primary and secondary windings are correct.

The measuring instrument connected to the secondary of the CT should be a high impedance voltmeter or a moving coil ammeter, with centre zero. A low voltage battery is used in series with a push-button switch in order to energise the primary. When the breaker is closed the measuring instrument should make a small positive deflection, and on opening the breaker there should be a negative deflection, if the polarity is correct.

This test checks out all the protection system, including the current transformers.February 8, 26 Comments. Test Procedure:. Method No: 1 Kelvin Bridge Method for measurement of winding resistance. Method No: 2 current voltage method of measurement of winding resistance. Filed under Uncategorized. About Jignesh.

Parmar B. Tech Power System ControlB. E Electrical. Membership No:M He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. Dear Sir, thank you very much for sharing useful information.

Power Transformer Testing and Commissioning Guidelines(Oil Type)

I have one quotation How to cross check the transformer rating during routine test or factory level test. Thanks and regards, Sharath Shetty. Thank u sir for sharing such useful information. No one can find such theories at any where which is very much essential for an Electrical Engineer when he starts career…….

Dear Sir, Thanking for the documents send. As I am required to provide training regarding switchgear and protection to my colleagues.

Common electrical tests on power transformers

Please provide how much meggar value found at LV and HV side and also provide many other things completaly please. Thanks and regards. Hi Jignesh, thanks for your insight into a lot of detailed information. I have a specific question about Medical imaging systems especially devices that require large input feeds in the V range like a Linear accelerator. Can you please give me an overview of the electrical distribution system with various components that are typically used to design a system from the main hospital feed to the similar equipment?

You can also send me an email directly. Thank you sir. It would be more helpful if the expected range of insulation resistance is also included in the IR test. It is really very helpful.

Various Routine Test of Power Transformer-(Part-1)

Thank You So Much…. Thanks Mr. Parmar for these useful compilations. Respected sir,this article helped me a lot in my lecture notes.

pre commissioning test of power transformer

Are routine tests part of condition monitoring of power transformers. I am doing thesis on condition monitoring of power transformers. You are commenting using your WordPress.An electrical power transformer has to go through a number of transformer testing procedures for confirming its specifications and performances. In this article, you will learn different types of transformer testing methods, test setup, and their acceptance criteria.

The transformer testing methods are broadly divided into two based on where the test is conducted. Some of the tests are done at the factory during the manufacturing process. Other tests are done at the site at the time of the transformer installation. The routine tests are performed on all transformers.

But type tests are performed on each unique design. Each of the above tests contains a series of tests which are briefly explained below. We will discuss each of the tests in detail in coming articles. Some transformer testing methods are carried out for confirming the basic design expectation of that transformer. Type tests are done mainly in a prototype unit not in all manufactured units in a lot.

The type tests of the transformer confirm the main and basic design criteria of a production lot. Routine tests of the transformer are mainly for confirming the operational performance of an individual unit in a production lot. Routine tests are carried out on every unit manufactured. Special tests of the transformer are done as per customer requirement to obtain information useful to the user during the operation or maintenance of the transformer. In addition to the above transformer testing methods, the power transformer also goes through some other tests, performed on it, before the actual commissioning of the transformer at the site.

The transformer testing performed before commissioning the transformer at the site is called the pre-commissioning test of the transformer. These tests are done to assess the condition monitoring of the transformer after installation and compare the test results of all the low voltage tests with the factory test reports.

Condition monitoring for transformers is the process of monitoring the parameters of conditions in transformer moisture, temperature, etc. This transformer testing method is conducted to determine the resistance.

Winding Resistance Measurement is one of the routine tests in a transformer. Also, to verify, through acceptable resistance readings, that all bolted connections are tight, and that crimped connections and conductor splices are adequate.

These are used to measure low resistances below 10 Ohms. The low current is necessary to insure against heating of the windings which would lead to false readings due to an increase in resistance. The variation in resistance measurements between phases of the same winding shall not exceed the limits specified by the transformer manufacturer. This equipment connects to each phase of the HV and LV winding and via the application of a very low voltage determines the ratio of the high voltage windings to the low voltage windings.

These values are compared to those supplied from Engineering.A primary part of commissioning a transformer involves testing it after its installation in the field. This amounts to a rigorous examination of the transformer intended to:. For many tests, this will be almost essential to diagnose problems effectively in the future. Transformers should be tested periodically through their lifetime. However, limitless testing is not a good use of budget and manpower and not necessary.

Some tests are well suited as screening tools while others make sense only under suspicion of specific problems.

pre commissioning test of power transformer

For example, unless there is reason to be concerned about winding deformation, a leakage reactance test is probably not necessary. The electrical field tests recommended for routinely testing a transformer include:. The list of electrical tests that should be used to diagnose a transformer is all inconclusive. Here it makes sense to intelligently choose, or at a minimum order, the tests to be performed based on symptoms of the transformer, operating and test history, etc.

Megger can help with this. The electrical field tests available to diagnose a transformer include:. Electrical test recommendations for transformers A primary part of commissioning a transformer involves testing it after its installation in the field. We use cookies to provide you with a better experience. Read more on our cookie policy.