What is PD IEC/TR 60865-2 - short circuit effect calculation standard about?
A short circuit (sometimes abbreviated to short or s/c) is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical impedance. This results in an excessive current flowing through the circuit. A short circuit in the power system is the result of some kind of internal and or external effects.
- Internal effects are caused by the breakdown of equipment or transmission lines from the deterioration of insulation in a generator, transformer, etc. Such troubles may be due to the aging of insulation. inadequate design or improper installation
- External effects causing short circuits include insulation failure due to lightning surges. overloading of equipment causing excessive heating: mechanical damage by public etc
The object of PD IEC/TR 60865-2, which is a Technical Report, is to show the application of procedures for the calculation of mechanical and thermal effects due to short circuits as presented in IEC 60865-1.
Who is PD IEC/TR 60865-2 - short circuit effect calculation standard for?
PD IEC/TR 60865-2 on short circuit effect calculation standard is useful for:
- Manufacturers of electrical cables
- Manufacturers of short circuit protection devices
- Concerned maintenance teams
- Product development / innovation / research teams
- Quality control teams
Why should you use PD IEC/TR 60865-2 - short circuit effect calculation standard?
A short circuit is simply a low resistance connection between the two conductors supplying electrical power to any circuit. This results in excessive current flow in the power source through the ‘short,’ and may even cause the power source to be destroyed. The technical report in PD IEC/TR 60865-2 is an addition to IEC 60865-1. It does not, however, change the basis for standardized procedures given in that publication. The following points should particularly be noted:
- The examples in this Technical Report illustrate how to make the calculations according to IEC 60865-1 in a simplified and easy-to-follow manner. They are not intended as a check for computer programs.
- The numbers in parentheses at the end of the equations refer to the equations in IEC 60865-1:2011
- The system voltages are referred to as nominal voltages
- The results are rounded to three significant digits.
- Short-circuit effects appear as exceptional load in addition to the mechanical loads of the normal operation of switchgear. In the following examples with rigid conductors, a possible static preloading is therefore calculated too. Depending on whether it concerns the load of the normal operation or the load during the short-circuit different safety factors come to use. The height of these factors has been chosen typically and is recommended for the use. However, other safety factors may be necessary depending on the safety concept.
The sections on mechanical effects on strained conductors, centre-line distance between sub-conductors, mechanical effects on strained conductors with dropper in the middle of the span have been discussed in thorough detail in PD IEC/TR 60865-2. Using PD IEC/TR 60865-2 guidelines you can determine the application of procedures for the calculation of mechanical and thermal effects due to short circuits. PD IEC/TR 60865-2 enables you to provide your operators with a safe working atmosphere and your users with safe and reliable products.
What’s changed since the last update?
PD IEC/TR 60865-2:2015 supersedes PD 6575-2:1995. PD IEC/TR 60865-2:2015 includes some technical changes with respect to PD 6575-2:1995. The important ones include:
- The determinations for auto reclosure together with rigid conductors have been revised
- The configurations in cases of flexible conductor arrangements have been changed
- The influence of mid-span droppers to the span has been included
- For vertical cable-connection, the displacement and the tensile force onto the lower fixing point may be calculated now
- Additional recommendations for foundation load due to tensile forces have been added