IEEE C57.18.10-1998 pdf download Errata to IEEE Standard Practice and Requirements for Semiconductor Power Rectifier Transformers
5.2.2 Loading at other than rated load
5.2.2.1 Liquid-immersed rectifier transformers
IEEE Std C57.12.00-1993 and IEEE Std C57.91-1995 define loading for other than rated load conditions forliquid-immersed rectifier transformers.
5.2.2.2 Dry-type rectifier transformers
IEEE Std C57.12.01-1989 and IEEE Std C57.96-1989 define loading for other than rated load conditions fordry-type rectifier transformers
5.2.3 Unusual temperature and altitude conditions
Rectifier transformers may be used at a higher or lower abient temperature or at higher altitudes than thosespecified in 5.1, but special consideration must be given to these applications. For unusual temperatures, theappropriate guides referenced in IEEE Std C57.12.00-1993 and IEEE Std C57.12.01-1989 apply. For alti-tude, Table 1,Table 2, and Table 3 in Clause 10 may serve as a guide.
5.2.4 Other unusual service conditions
Other unusual service conditions include the following!
aDamaging fumes or vapors, excessive or abrasive dust, explosive dust or gases, steam, salt spray.
excessive moisture or dripping water, etc.
6iAbnormal vibration,shocks.or tilting.
c)Unusual transportation or storage conditions.
d)Unusual space limitations.
elUnusual operating duty, frequency of operation, difficulty of maintenance, poor wave form, unbal.
anced voltage, special insulation requirements, high source impedance, etc.
0The presence of any dc current in transformer windings either from load or supply side.
5.2.5 Transformers energized from a convertor/inverter
Transformers energized from a convertor/inverter are often subject to considerably distorted voltages. Generally, voltage harmonics are considered to be low with regard to loss correction and negligible in therma.design considerations. If voltage distortions are known to be above the specified limits in IEEE Std 5191992, information shall be given in the specification with details of the service conditions
Variable frequency applications are generally considered to be constant volts per hertz, unless noted otherwise. If the volts per hertz is variable, the degree of variation shall be given in the specification. The amplitude of the fux density in the core is the most important factor, not the maximum value of the nonsinusoidavoltage.
6. Rating data
The kVA rating of a rectifier transformer shall be the kVA drawn from the line.
6.1 Taps on rectifier transformers
If taps are provided they shall be considered to be, unless otherwise specified, only a means of adjusting forsustained departures in alternating supply voltage. These shall be rated kVA primary taps.
When taps are provided in the rectifier transformer for adjusting the output voltage, the taps providing outputvoltages above rated voltage shall be rated kVA taps, and the output current shall be reduced in proportion tothe increase in output voltage, thereby maintaining rated kilowatt output. The taps providing output voltagesbelow rated voltage shall be reduced kVA taps, the output currents shall not exceed the current specified, andvoltage variation shall not exceed +10%.
6.2 Cooling classes of transformers
Use “Cooling Classes of Transformers” in IEEE Std C57.12.00-1993 and “Limits of Temperature Rise”inIEEE Std C57.12.01-1989.
6.3 Frequency
The frequency of rectifier transformers covered by this standard shall be 60 Hz unless otherwise specified
6.4 Phases
See Table 9 for selection of number of primary and secondary phases.
6.5 Rated kVA
6.5.1 Line kVA rating
IEEE C57.18.10-1998 pdf download
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