IEEE C57-142-2010 pdf download IEEE Standard General Requirements for Dry-Type Distribution and Power Transformers Including Those With Solid Cast and/or Resin-Encapsulated Windings
41 Usual Service Conditions4.1.1 General.Transformers conforming tothis standard sltall be suitable for operation atrated kVA under the following usual service conditions.
4.1.2 Temperature
4,1.21 The tenpcraturc of the cooling air(amnbicnt temperaturc) sllall not execed 40 !alidl the average temperature of the cooling ajr forany 24h period shall not exceed 30 C.
4.1.2.2 The minimum ambient temperatureshall not be lower than -30 C.
4.13 Alitude.Tlte altitude shall not exceed8300 (1000 )
4.1.4 Supply Voltage.The supply voltagc waveshape shall be approxinintcly sinusoi(al, and thcphasc voltngcs suplying a polyphase transformershall be approximately ecunl in magnitudo and ofapproximate equal time phase displacement.4.1.5 Load Current，The load current shall beapproximnatcly sirsoical. The harmonic factorshall not (xceed 005 per unit.NOTK:“!urmonie actor” is defined ANSI/TEEE C57.12.801078(11].
416 Operation above Rated Voltage
4.1.6.1 Trrsforinerg shall be capable of:
Delivering ratec output in kVA at 5% abovcrated sccondary voltage, without excecding the limiting tempcrature rise, when thcpowar factor of the load is 80% or higherOpcrating at 10% above rated secondaryvoltage at no load withont exceeding thelimiting temperature rise.
Fulfilling the foregoing requirenents forrated voltage, rated frequency, and ratedkVA lor any tup.4.1.6.2 Thomaxmum continnous transformer operating voltage should not cxcecd the