It has been developed with the assistance of bureau of reclamation engineers. It detects winding defects and faults in the magnetic core thereby helping to improve transformer reliability, reduce maintenance costs and prevent costly failures. Turn on the sfra test instrument and wait 20 seconds. Sweep frequency response analysis sfra is one of the most powerful diagnostic tools for assessing. Each frequency range corresponds to dfferent components in the transformer. It measures the frequency response of passive element rlc of the apparatus. The sfr analyzer identifies the following abnormalities in the. Pdf statistical approach for interpretation of power. Sfra testing basics offline test the transformer is seen as a complex impedance circuit open excitation current and short shortcircuit impedance responses are measured over a wide frequency range and the results are presented as magnitude response curves filter response changes in the impedance can be. The power transformer of rating 10 kva, 1 v440 v, 3phase, 50 hz, dyn11 has been specially developed inhouse for carrying out sfra testing by. In this test configuration, input test signal is applied to one end of a winding and the response is measured at one end of another winding on the same phase. Sfra testing basics offline test the transformer is seen as a complex impedance circuit open magnetization impedance and short shortcircuit impedance responses are measured over a wide frequency range and the results are presented as magnitude response curves filter response changes in the impedance.
Sweep frequency response analysis given below is a list of sweep frequency response analysis projects executed by us. This includes methods to determine if the corrosive sulfur. Sweep frequency response analysis sfra test on transformer. A sfra open circuit test will show the response of core and windings, while a sfra short circuit test only shows the response of windings. Sweep frequency response analysis test or in short sfra test can detect efficiently, displacement of transformer core, deformation and displacement of winding, faulty core grounds, collapse of partial winding, broken or loosen clamp connections, short circuited turns, open winding conditions etc. Experimental investigations to identify sfra measurement. By using the latest proven sfra test techniques, it is possible to accurately assess transformer condition without dismantling it.
Sfra, detect of winding deformation in power transformer. In 2012 the transformer was again subjected to sfra test. Sfra is an electrical test that provides information relating to transformer. The sweep frequency response analysis sfra is an analysis technique for detecting winding displacement and deformation among other mechanical and electrical failures on power and distribution transformers. For example, valves positioned incorrectly, plugged radiators, stuck temperature indicators and level gauges, and noisy oil pumps or fans. Nov 17, 2019 sweep frequency response analysis test or in short sfra test can detect efficiently, displacement of transformer core, deformation and displacement of winding, faulty core grounds, collapse of partial winding, broken or loosen clamp connections, short circuited turns, open winding conditions etc. Inspect transformer and parts for shipping damage and moisture. By adjusting cursor positions to frequency subbands, new autocorrelation constants can be calculated.
A change in winding position, degradation in the insulation, etc. Connect the test lead bnc connectors to the frax instrument, generator yellow, reference. The test in progress and system ok indicator lights come on. Iec6007618 sfra of power transformers, typical test sequences this application note will discuss typical transformer configurations and measurement sequences as specified in the iec6007618 international standard. Frequency response transformer testing sfra all about. As per iec specifications, test should be carried out by applying double the r. Sfra, detect of winding deformation in power transformer doi. It is also known as iovtinduced over voltage test, it is one of the routine test of transformers usually performed to check in turn insulations of the windings. This highlyaccurate verification device confirms that your equipment is providing you with results you can trust. Result analysis and reporting after the measurement a reference test of the same. The latest sfra test sets make these techniques more accessible, more convenient and more dependable that ever.
This guide is based on the operation of the n4l sfra45 sweep frequency response analyzer and will provide a. Non typical fault detection in power transformers using sfra. The measurement of sfra can be a part of regular transformer maintenance. Most dielectric and mechanical failures in large power transformers are. Expert system for sweep frequency response analysis of. Condition monitoring of power transformer by using sfra test. Frequency response analysis of power transformers 100215. Feb 23, 2012 if a good reading is found the transformer is good. Pdf measurement of shortcircuit effects on transformer winding.
Sweep frequency response analysis test or in short sfra test can detect. Following is an approximate sequence for transformer testing. The megger technical library provides access to a range of additional content and resources such as technical guides, application notes and more. Abb trafositetesting is the transformer test floor that comes to your site the abb tres mobile highvoltage power transformer test system enables abb tres to perform a full range of testing on all types and brands of transformers, reactors, cables and other hv equipment. In this test you can understand the diagnosis of transformer. In this paper the method of sweep frequency response analysis sfra has been proposed for on site and instant test of oil condition without requiring the transformer to be opened and sending oil. An electrical test procedure for determination of copper. Test your sfra instrument and leads together or test the instrument using the included hook up cables. This is also true for other, especially mechanical, faults.
Based on the theory of the previous chapter, a value of remanent magnetization was minimal. This paper presents how interpretation of sweep frequency response analysis sfra traces can be done for the open circuit and short circuit winding faults on the 10 kv a power transformer. Pdf on site oil test for a transformer using sweep. Measurement of shortcircuit effects on transformer winding with sfra method and impact test.
Typically, a baseline is taken in the factory to which all subsequent test results are compared. An electrical test procedure for determination of copper sulfide contamination in transformer windings lance r. The sfra 5000 offers both high precision and portability in a single package, providing all the accessories required for fast, easy to use, reliable and repeatable measurements. To get value from an sfra test it is necessary to make sure that the measurements are credible, which requires good test technique and simple procedures. Power outages cause loss of income for power consumers and.
Pdf condition monitoring of power transformer by using sfra test. In all cases the specimen under test transformer, reactor, etc. Sweep frequency response analysis electrical test equipment. Sfra is condition monitoring technique for expensive power equipment. The winding of transformer may be subjected to mechanical stress. An initial sfra test is carried out to obtain the signature of the transformer frequency response by injecting various discreet frequencies. This is a case where a sweep frequency response analysis sfra test will become invaluable.
Sfra is an off line testing and it can be carried out for any voltage rating of power transformer, generator transformer and distribution transformer. Theres no need to retype or reformat your documents. In this paper the method of sweep frequency response analysis sfra has been proposed for onsite and instant test of oil condition without requiring the. Sfra 5000 is a standalone sweep frequency response analyzer for the high accuracy transformer analysis and integrates the sts and td 5000 family test sets. The latest sfra test sets make these techniques more accessible, more convenient and. To improve the quality of your regular inspection program.
Lewand, doble engineering company introduction over the past several years there has been much work performed to determine if an oil has corrosive sulfur present. This test is very reliable for condition monitoring of physical condition of transformer windings. The power transformer of rating 10 kv a, 11,000 v440 v, 3phase, 50 hz, dyn11 has been specially developed inhouse for carrying out sfra testing by. Apr 29, 2018 hello, this video is for deep understand about sweep frequency response analysis sfra on transformer. The test methods used by the authors for presenting the results are described. Transformers are the most critical part of electrical transmission and distribution network, also when it is come to quality and continuity requirements on delivery of electrical energy. Sweep frequency response analysis test sfra test electrical4u. Basics, maintenance, and diagnostics vii contents continued page 4. Abbyy pdf transformer not only captures text but also recreates all formatting elements titles, tables, columns, pictures, charts, hyperlinks and internal links, etc. Sfra sweep frequency response analysis, leakage reactance, and normal power factor measurements were. The following traces were obtained using the doble sfra software for m5200m5300. A measurement setup accompanied by a transformer as a test object, on which winding faults are imposed, completes the test setup for performing the fra measurements. Sfra testing on transformers dismantling a power transformer to determine its condition is hardly ever a practical possibility.
Hello, this video is for deep understand about sweep frequency response analysis sfra on transformer. Sfra and additional transformer test results to get a comprehensive overview of. Before proceding with transformer measurements the test engineer will become familiar with the safety rules of section 2. Frax sweep frequency response analyzer sfra is designed to detect. The test in progress and system ok indicator lights go out. Interpretation of sweep frequency response analysis sfra. All other terminals of the transformer left floating. Sweep frequency response test in the most of the commercial sweep frequency response measuring instruments, the measuring task is. Transformer service trafositetesting verify the reliability of your transformers abb transformer remanufacturing and engineering services tres proudly offers comprehensive onsite transformer testing services with our highvoltage mobile test system. What is the correct procedure for dvdf and hv test on. This test configuration is intended to check the response due to the influence of space between two windings in a particular phase.
Iec6007618 sfra of power transformers, typical test. Sfra and the role it plays in transformer test and maintenance. In a power transformer it measures the fault current of the winding over a wide range of frequencies. The doble m5150 can be used in the field or in the office allowing you to isolate problems between hardware and cables. Sweep frequency response analysis sfra for the assessment. Dismantling a power transformer to determine its condition is hardly ever a practical possibility. This reference is then used for future comparisons. The transformer to be tested must be completely isolated from the power system.
That time, transformer was out of operation for almost 9 months. Anytime a transformer is moved there is a possibility of damage to this transformer. Power transformer, internal faults, frequency response analysis, maintenance and condition monitoring, sweep frequency response analyser. Jan 08, 2019 sfra stands for sweep frequency response analysis. The winding of transformer may be subjected to mechanical stresses during transportation, heavy short circuit faults, transient switching. Nowadays, there is an increasing interest in sfra method because of its sensibility in detecting mechanical faults without opening the unit. Main core deformation, open circuits, shorted turns, residual magnetism. The sweep rate response analysis is wide used technique for establish veiled fault and circumstance observance of power electrical device. Sfra testing on transformers electrical test equipment. If a good reading is found the transformer is good. The action is administrated by provide a coffee voltage signal of changeable frequencies to the electrical device windings and measures each the input and output signals.
Sfra and additional transformer test results to get a. It is useful to correlate the two methods to increase the precision of the result. No load losses at 60 hz and 50 hz failure localization shortcircuit impedance. According to 3 sfra method determines the transformer responses in a time or frequency area.