IEC 60044-2:1997 pdf download – lnstrument transformers -Part 2: Inductive voltage transformers

IEC 60044-2:1997 pdf download – lnstrument transformers -Part 2: Inductive voltage transformers.
This pan of IEC 44 applIes to new inductive voltage transformers for use with electrical measuring instruments and electrical protective devices at frequencies from 15 Hz to 100 Hz.
Although this standard relates basically to transformers with separate windings. it is also applicable, where appropriate, to auto-transformers. This standard does not apply to transformers for use in laboratories.
NOTE — Requirements spcitic to three-phase voltage transtormers are noq included In tti. standard but so tar as they are relevant, Pie requ.rements m clauseS 3 to II apply to these transtomiws and a few retereacea to them age Included In those clauses (e.g. see 2.1.4, 51 I. 5.2. and lI.2J.
Clause 13 covers the requirements and tests. In addition to those in clauses 3 to 12, that are necessary for single-phase inductive protective voltage transformers. The requirements of clause 13 apply particularly to transformers which are required to have sufficient accuracy to operate protective systems at voltages that occur under fault conditions,
1.2 Normative references
The following normative documents contain provisions which, through reference in this text. constitute provisions of this part 01 IEC 44. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this part of lEG 44 are encouraged to investigate the possibility of applying the most recent editions of the normative documents Indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
IEC 28:1925, Internaponal standard of resistance for copper
IEC 38:1983, IEC standard voltages
lEG 50(321): 1986, International Electrotechnical Vocabulary — Chapter 321: Instrument transformers
IEC 60-1:1989, Hsigh-volrage test techniques — Pan 1: General definitions and test requirements
IEC 71-1: 1993. Insulation co-ordination — Part 1: Definitions, principles and rules
IEC 85:1984, Thermal evaluation and classification of electrical insulation
IEC 270:1981, Partial discharge measurements
IEC 721: Classification of environmental condit,ons
IEC 815:1986, Guide for the selection of insulators in respect of polluted conditions
2 DefInitions
For the purpose of this part of IEC 44, the following definitions apply.
2.1 General definitions
2.1.1 Instrument transformer: A transtormor intndod to supply measuring instruments, meters, relays and other similar apparatus. (1EV 321-01 -01 modifiedJ
2.1.2 voltage transformer: An instrument transformer in which the secondary voltage, in normal conditions of use, is substantially proportional to the primary voltage and differs in phase from it by an angle which is approximately zero for an appropriate direction of the connections. 11EV 321-03-01)
2.1.3 unearthed voltage transformer A voltage transformer which has all parts of ts primary winding, includii terminals, insulated from earth to a level corresponding to its rated insulation level.
2.1.4 earthed voltage transformer: A single-phase voltage transformer which is intended to have one end of its primary winding directly earthed or a three-phase voltage transformer which Is intended to have the star-point of its primary winding directly earthed.
2.1.5 primary winding: The winding to which the voltage to be transformed is applied.
2.1.6 secondary winding: The winding which supplies the voltage circuits of measuring Instruments, meters, relays or similar apparatus.
2.1.7 secondary circuit The external circuit supplied by the secondary winding of a translormer.
2.1.8 rated primary voltage: The value of the pnmary voltage which appears in Itie designation of the transtormer and on which its performance is based. (1EV 321 -01 -12 moditiedj
2.1.9 rated secondary voltage. The value of the secondary voltage which appears In the designation of the transformer and on which its performance is based (1EV 321-01-16 modifiedj
2.1.10 actual transformation ratIo: The ratio of the actual primary voltage to the actual secondary voltage 11EV 321-01-18 modifiedj
2.1.11 rated transformation ratio: The ratio of the rated primary voltage to the rated secondary voltage. 11EV 321-01-20 modifIed)
2.1.12 voltage error (ratio error): The error which a transformer introduces into the measurement of a voltage and which arises when the actual transformation ratio is not equal to the rated transformation ratio. (1EV 321 -01-22 modified)
The voltage error, expressed in per cent, is given by the formula.