Common use of Type Tests Clause in Contracts

Type Tests. One transformer of each type shall be subjected to the following type tests. Impulse-Voltage Withstand Test - One transformer of each outdoor design, rating and voltage ratio shall be tested in accordance with IEC 60076-3: 2000, Clauses 12 and 13. Neutral terminals shall be connected as in service, i.e. neutrals of fully insulated windings shall be left isolated. Approved means shall be provided to prevent voltages in excess of 75% of the design impulse voltage of the associated winding from appearing at the line terminals not under test. Except where modified below at least one terminal of the winding or windings not under test on the same limb as the winding under test shall be solidly earthed. The transformer tank shall be efficiently connected by low impedance copper strip to the impulse generator earth point and the whole well earthed. Arcing horns, if fitted to the transformer bushings, shall be adjusted to the maximum setting permitted by the bushing design or shall be removed. Temperature Rise Test - One transformer of each rating and voltage ratio with is own tank, voltage control apparatus, and cooling apparatus, if any, shall be tested in accordance with the provisions of IEC 60076. Unless otherwise agreed with the Engineer the temperature rise test shall be carried out with the transformer on normal ratio. Capacitance Test - The capacitance between windings and to earth shall be measured by an approved method. Short Circuit Test - When required by the Engineer a full voltage short-circuit test shall be performed on a typical transformer. With the high voltage winding energized at full voltage from a supply source which will maintain this voltage under fault conditions, a short-circuit shall be applied to the low voltage terminals and held for 5 seconds in accordance with the Specification Clause headed "Duty Under Fault Conditions". It shall be demonstrated that the transformer has sustained no damage as a result of this test. A separate price for this test shall be entered in Schedule 'J2'. Noise Level Test - Noise levels shall be measured with the transformer on no load at normal voltage and frequency. Where a transformer has more than one rating, measurements shall be repeated with the cooling system corresponding to each rating in operation. All readings shall be made at the "A" weighting using a precision sound level meter conforming to IEC.61672. The calibration of this instrument shall be verified before and after the tests. The background noise level shall be of the order of 10 dB. Wherever possible the transformer shall be positioned at least 3 m from any reflecting surface. Where this is not possible any readings influenced by reflections may, at the discretion of the Engineer be disregarded when computing the average noise level. Measurements shall be made at intervals not exceeding 1 m in a horizontal plane 1.2 m or half the tank height, whichever is the lesser, above the tank base. The microphone shall be located at points situated 0.3 m from an imaginary strin passed round the transformer to include all major projections from the tank but excluding valves and similar fittings. The average surface noise level shall be calculated from the average of the readings obtained

Type Tests. One transformer of each type shall be subjected to the following type tests. Impulse-Voltage Withstand Test - One transformer of each outdoor design, rating and voltage ratio shall be tested in accordance with IEC 60076-3: 2000, Clauses 12 and 13. Neutral terminals shall be connected as in service, i.e. neutrals of fully insulated windings shall be left isolated. Approved means shall be provided to prevent voltages in excess of 75% of the design impulse voltage of the associated winding from appearing at the line terminals not under test. Except where modified below at least one terminal of the winding or windings not under test on the same limb as the winding under test shall be solidly earthed. The transformer tank shall be efficiently connected by low impedance copper strip to the impulse generator earth point and the whole well earthed. Arcing horns, if fitted to the transformer bushings, shall be adjusted to the maximum setting permitted by the bushing design or shall be removed. Temperature Rise Test - One transformer of each rating and voltage ratio with is own tank, voltage control apparatus, and cooling apparatus, if any, shall be tested in accordance with the provisions of IEC 60076. Unless otherwise agreed with the Engineer the temperature rise test shall be carried out with the transformer on normal ratio. Capacitance Test - The capacitance between windings and to earth shall be measured by an approved method. Short Circuit Test - When required by the Engineer a full voltage short-circuit test shall be performed on a typical transformer. With the high voltage winding energized energised at full voltage from a supply source which will maintain this voltage under fault conditions, a short-circuit shall be applied to the low voltage terminals and held for 5 seconds in accordance with the Specification Clause headed "Duty Under Fault Conditions". It shall be demonstrated that the transformer has sustained substained no damage as a result of this test. A separate price for this test shall be entered in Schedule 'J2'. Noise Level Test - Noise levels shall be measured with the transformer on no load at normal voltage and frequency. Where a transformer has more than one rating, measurements shall be repeated with the cooling system corresponding to each rating in operation. All readings shall be made at the "A" weighting using a precision sound level meter conforming to IEC.61672. The calibration of this instrument shall be verified before and after the tests. The background noise level shall be of the order of 10 dB. Wherever possible the transformer shall be positioned at least 3 m from any reflecting surface. Where this is not possible any readings influenced by reflections may, at the discretion of the Engineer be disregarded when computing coputing the average noise level. Measurements shall be made at intervals not exceeding 1 m in a horizontal plane 1.2 m or half the tank height, whichever is the lesser, above the tank base. The microphone shall be located at points situated 0.3 m from an imaginary strin passed round the transformer to include all major projections from the tank but excluding valves and similar fittings. The average surface noise level shall be calculated from the average of the readings obtainedobtained Tank Vacuum Tests - One transformer tank of each size shall be subjected when empty of oil to a vacuum of 70 kN/m2 below atmospheric pressure. The permanent deflection of flat plates after the vacuum has been released shall not exceed the value specified below.