SN EN 60524 : 1993 AMD 2 1997

National foreword
Cooperating organizations
1 Scope
2 Terms and definitions
2.1 D.C. resistive volt ratio box (hereinafter
      designated "VRB")
2.2 Rated voltage(s)
2.3 Nominal voltage ratio
2.4 True voltage ratio
2.5 Circuit installation voltage (nominal circuit
      voltage)
2.6 Auxiliary equipment
2.7 Leakage current screen (circuit)
2.8 Electrostatic screen
2.9 Ripple content
2.10 Common mode voltage
2.11 Influence quantity
2.12 Variation with influence quantity
2.13 Reference conditions
2.14 Reference value
2.15 Reference range
2.16 Nominal range of use
2.17 Limiting values of an influence quantity
2.18 Fiducial value
2.19 Error
2.20 Error expressed as a proportion of the fiducial
      value
2.21 Intrinsic error
2.22 Accuracy
2.23 Accuracy class
2.24 Class index
2.25 Parasitic voltage
3 Classification
4 Limits of intrinsic error
4.1 Permissible limits of intrinsic error
4.2 Multiple ratio VRBs
4.3 D.C. parasitic voltages
5 Conditions for the determination of intrinsic
      errors
6 Permissible variations
6.1 Limits of variation
6.2 Conditions for the determination of variations
6.3 Variation due to common mode voltage (see Appendix
      A)
7 Additional electrical and mechanical requirements
7.1 Effect of self-heating
7.2 Voltage tests and other safety requirements
7.3 Insulation resistance test
7.4 Limiting temperature for storage, transport and
      use
8 Information, markings and symbols
8.1 Information
8.2 Markings, symbols and their locations
8.3 Documentation
8.4 Examples of the marking of a VRB
Appendix
A Determination of the effect of common mode voltage
      (see Figure 2)

Concerns d.c. resistive volt ratio boxes with fixed ratios and rated input voltage up to 1.5 kV and a class index of 1000 parts per million or better. Relates to all equipment which is built in or is supplied by the manufacturer as an essential part of the volt ratio box. Includes sections on nominal and true voltage ratio, circuit insulation voltage, leakage current screen, electrostatic screen, ripple content, common mode voltage, influence quantity, fiducial value, error, parasitic voltage, multiple ratio VRBs, permissible variations, effect of self heating, voltage tests and other safety requirements, insulation resistance test, limiting temperature for storage, transport and use, marking, symbols and documentation.