Page 444 - Industrial Power Engineering and Applications Handbook

13/41 8 Industrial Power Engineering and Applications Handbook

Relevant Standards
~ ~
IEC Title IS BS IS0
Methods of test for ready mixed paints and 101-1 to9 BS 3900 3205, 3210
enamels
Method for specifying phosphate conversion 3618/1991 BS 3189/1996 9717/1990
coatings for metals 6005/1991
Apparatus for salt spray test 11864/1991 - -
Specification for electrostatic hand held spraying - BS EN -
equipment for non flammable material for 5OO59/199 1
painting and finishing

Relevant Standards of American Society for Testing Materials
ASTM DI654/- Standard method for evaluation of painted or coated
79a/1984 specimens subjected to corrosive environments
ASTM B117/1990 Standard test method of salt spray (FOG) testing

Notes
1 In the tables of relevant Standards in this book while the latest editions of the standards are provided, it is possible that revised editions
have become available. With the advances of technology and/or its application, the updating of standards is a continuous process by
different standards organizations. It is therefore advisable that for more authentic references, readers should consult the relevant
organizations for the latest version of a standard.
2 Some of the BS or IS standards mentioned against IEC may not be identical.
3 The year noted against each standard may also refer to the year of its last amendment and not necessarily the year of publication

List of formulae used Fault current
I . Rated current
Isc = 1.e.
Selection of bases Z, Short-circuit unit impedance (1 3-51
Actual quantity Base MVA etc.
Per unit quantity, p.u. = (13.1) Fault MVA = (1 3.6)
Chosen base ZP
Actual impedance

z- v2 n (13.2) Further reading
I - WA x 1000
If Zp is the p.u. impedance then
1 Beeman, D. (ed.), Industrial Power Systems Handbook, McGraw-
Z, . (base kVA) x 1000 Hill, New York.
z, = (1 3.3)
Base V2 2 Coelho, F. ‘Modern MCC designs’, Siemens Circuit, XXII, July,
No. 3 (1987).
3 Lythall, R.T., Group motor control boards, Electrical Review
(1 3.4)
30 June (1961).
4 Lythall, R.T., The J & P Switchgear Book, Butterworths.
= p.u. impedance at the original base, and 5 Lythall, R.T., Sitnplijied Short-circuit Culculations, Belmos
Zp2 = p.u. impedance at the new base Peebles Ltd.