Calculation acc. to IEC 61400 part 4

Symbol -
Unit -
Attribute-ID stplus_switch_iso_iec_61400_4
Numeric ID 9473
Value Type PMBoolean

The IEC 61400-4: Wind turbines – Part 4: Design requirements for wind turbine gearboxes (2012) standard is based on the ISO standard system for determining the load carrying capacity of gearboxes.

Boundary conditions for determining the flank and root load carrying capacity

For determining the flank and root load carrying capacity, the standard is based on  ISO 6336 The following boundary conditions are set, among others (references refer to the sections in IEC 61400-4:2012):

  • Load spectrum calculation according to Miner should be used (load spectrum provided by the wind turbine manufacturer)(See section 7.2.2.1)
  • ZNT and YNT should be reduced to 0.85 at 10^10 load cycles (see section 7.2.2.1)
  • The gearbox operating hours should correspond to at least the forecast lifetime of the system (see section 7.2.2.1)
  • Safety against pitting should not be less than 1.25 (see section 7.2.2.1)
  • Safety against tooth root fracture should not be less than 1.56 (see section 7.2.2.1)
  • Static pitting resistance should be greater than 1.0 (see section 7.2.2.4)
  • Static security against tooth root fracture should be greater than 1.4 (see section 7.2.2.4)
  • Kv should be determined according to Method B (ISO 6336-1:2006). If the calculation results in a value less than 1.05, the value should be set to 1.05. (see section 7.2.3.2)
  • Kγ for planetary gears according to Table 3 (see section 7.2.3.2)
  • KHβ should be determined according to a higher value method (ISO 6336-1:2006 Method B) and should not be less than 1.15. (see section 7.2.3.4)
  • KHα and KFα can be set to 1.0 if the required quality according to Table 4 is met (see section 7.2.3.4.3)
  • Material values σHlim ad σFE aus ISO 6336-5 (see section 7.2.4)
  • Quality according to ISO 1328-1 (Table 4) External Gears: 6 or greater
  • Internal gears: 7 or greater (8 is also permissible for nitrided ring gears) (see section 7.2.6)
  • RzH <= 4.8 mm (see section 7.2.7.2)
  • RzF <= 9.6 mm (see section 7.2.7.2)

Different values for the individual factors can also be directly specified in the FVA-Workbench.

Boundary conditions for the scuffing calculation

In the scuffing calculation, methods according to ISO/TR 13989-1, ISO/TR 13989-2, DIN 3990-4 and ANSI/AGMA 925-A02 are permitted (see IEC 61400-4:2012 section 7.2.2.2)

  • The scuffing risk according to ANSI/AGMA 925-A02 should not be less than 5 %.
  • The minimum security according to ISO/TR 13989-1, ISO/TR 13989-2 and DIN 3990-4 should not be less than 1.3.
  • The scuffing load capacity of the oil is to be determined according to ISO 14635-1. For the scuffing calculation, one level less than the failure level in the test should be used. If no scuffing test has been performed, level 12 can be used for the calculation.