Buy BIS IS (R) SPECIFICATION FOR DRY-TYPE POWER TRANSFORMERS from SAI Global. Since dry-type power transformers are not made for such high voltages and ratings as oil-immersed transformers, a large portion of IS: * serves no purpose. pdf – Download as PDF File .pdf), Text File .txt) or read online. SPECIFICATION FOR DRY-TYPE POWER TRANSFORMERS Transformers Chairman.

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Part 2 Measuring current transformers jirst revision. NOTE – In view of the fact that the transtormers will be operated at two different taps the winding temperature-rise of two transformer may be slightly different. By agreement between the manufacturer and the purchaser at the time of the enquiry, tests may be made with positive polarity, but in this case sudden changes of polarity have to be avoided.

The test sequence per line terminal shall be one calibration impulse at a voltage between 50 and 75 percent of the full voltage followed by three impulses at full voltage. Thus, for convenience sake, this separate and concise standard has been prepared to set out specific requirements for drytype power transformers.

IS 11171 (1985): Dry-Type Power Transformers

Part 3 Insulation level and dielectric 13 tests IS: For the purpose of determining when constant temperature conditions have been achieved, thermocouples, thermistors, RTDs drry thermometers shall be applied to the following surfaces: Letter symbols for use in connection shall be as given in Table 2. The procedure shall be as given in Part 1 General first revision.

Part 3 Insulation level and dielectric tests second revision. While such conditions may have little or no effect on a sealed, dry-type transformer, they may have serious effects on other kinds of dry-type txansfbrmer.

Part 1 General Jirsi reuision. Any site conditions which may either impose restrictions on the cooling air or produce high ambient air temperatures should be stated by the ipurchaser.

The provisions out by mutual 18 ; of acoustic sound level 19 ; and test Part 3 Insulation 21 levels transformfrs and for each of 11117, lim;ts, and dielectric tests B The low-voltage winding shall be supplied from a three-phase or single-phase source, depending on whether the transformer itself is three-phase or single-phase. The full test voltage shall be applied for 60 s between the winding under test and all the remaining windings, core, frame and transformer enclosure, connected to earth.


The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. Introduction to Power Generation and Transmission. Calibration is carried out as described in Appendix A of IS: Enclosed or non-enclosed non-encapsulated-winding dry-type transformers are normally designed for installation indoors in dry locations.

IS (): Dry-Type Power Transformers

In addition to high or low ambient temperature and high altitude, other environment conditions which may affect design and application can exist and are not necessarily covered by this standard. Part 1 General requirements first revision. Standard vry the assurance that they have been produced transformes comply witb the requirements of ytpe standard under a well-defined system of inspection, testing and and supervised by IS1 and operated by the quality control which is devised producer.

Information on the gas, if required, to fill the enclosure; g h 3 k 4 Method Indoor of cooling; or outdoor installation; Rated power in LVA ; Rated voltage for each winding ; State whether tappings are required, and circuit tap-changers or links are required; 20 if SO, whether off- 4 Highest voltage for equipment, U, transformres each winding ; P Insulation level, that is, values of test voltage at power frequency and, if required, lightning impulse ,for which each winding is to be designed [see IS: NOTE consideration The above does not apply to sealed should be given to bushings.

Part 2 Measuring voltage transformers jirst rruision. If it is, the degree of protection of the enclosure see NOTE- When a transdormers has windings of different insulation system temt peratures class of insulationonly one reference temperature is, the one relating to the winding having the higher inrulation NOTE- In dry-type transformers, the lightning impulse test can give rise to capacitive partial discharges in the air which do not endanger the insulation.

For greater altitudes, see 3. The repetition rate of calibration pulses should be of the order of twice the frequency of the excitation voltage. Cl Wave-shape of supply uoltage – A supply voltage shape is approximately sinusoidal. The choice between Lists 1 and 2 should be made by considering the degree of exposure to lightning and switching overvoltages, the type of system neutral earthing and, where applicable, the type of overvoltage protective device.


Part 3 Insulation levels and dielectric 8 tests Isrlll7l-r98!! These ratings shall be such that the transformer can deliver its rated current under steady loading conditions without exceeding the limits of temperature-rise specified in Section 3, assuming that the applied voltage is equal to the rated voltage and that the supply is at rated frequency. Geafol encapsulated dry-type transformers are required for indoor installations where safety and.

Part 1 General requirements Jirsl revision.

Guidance may be obtained from Part 3 Insulation levels second revision. When the test frequency duration of the test shall be: NOTE – Insulating materials may be used separately or in a combination providing that, in any application, each system will not be continuously subjected to a temperature in tansformers of that for which it is suitable when operating under rated conditions.

Oblique strokes shall be used to separate the group of symbols for different cooling methods for the same piece of equipment.

IS 11171: Dry-Type Power Transformers

Part 3 Protective current transformers jfirst revision. Part 1 General Jirsl revision. Afo NOTE – necessary.

The short-circuit run with rated current flowing in one winding and the other winding short-circuited is started immediately following the noload run, and continued until steady-state conditions are obtained when transformera individual winding temperature rises, A BO, are measured. Part 4 Terminal markings, tappings and connections Jirst revision. It may be performed on all kinds of dry-type transformers, but is especially applicable to transformers having encapsulated windings.

Temperature tests are made by utilizing the rises obtained tests, one with no-load loss only, and one with load losses only, short-circuit run. Dry-Type Power Transformers advertisement.

Furthermore, in the case of a single-phase phase-to-neutral and tested according to Furthermore, the electrical and mechanical properties of the insulated winding must not be impaired by the application of the hot-spot temperature permitted for the specrfic insulation system.

IS1 marked products are also continuously checked by IS1 for conformity to that standard as a further safeguard.