LATEST Version of Sag Calculator: v3.6 released on 23-Oct-2013.
Overhead Cable Sag Calculator, or more simply Sag Calculator, is a computer program that calculates the sag of overhead cables, such as the conductors and earthwires used for electrical transmission and distribution lines, the cables used for chairlifts, telephone cables, and so on.
Sag Calculator works on desktop, laptop, and/or netbook IBM PC compatible (i.e. PC's) computers running Windows 95, Windows 98, Windows ME, Windows NT, Windows 2000, Windows XP, Windows Vista, Windows 7, Windows 8, Windows 10 - for all x86 and x64, 32 and 64 bit, versions of Windows.
Sag Calculator allows you to work in and change between metric or imperial units.
Sag Calculator has two modes of operation:
- Sag Mode: for tensioning (or sagging) new cables or for re-tensioning (or re-sagging) existing cables. The required sags must be provided in a schedule or read from a stringing chart.
- Check Mode: for checking tensions (or sags) in new or existing cables. In this mode the actual sag is measured.
The rationale adopted for Sag Calculator has been to keep the user inputs as simple as possible and to perform the task with the least complicated equipment possible. Therefore conductor tension constraints are not required; conductor properties are not required for the majority of methods and distance measurements are a last resort.
Sag and/or check modes can be performed using a variety of methods:
- Tangent sighting methods:
- Sightboard method
- Level sighting method
- Single span tangent sighting method
- Two span tangent sighting method
- Timing methods:
- Travelling wave method
- Pendulum or swing method
- Tension methods:
- Series dynamometer method
- Shunt dynamometer method
- Clearance methods:
- Height stick method
- Two span offset method
- Other methods:
- Clino 1 Span
- Clino 2 Span
Sag Calculator comes with a suite of methods for sagging cables and for checking the cable sag. Each method has been field tested and the results have been confirmed by independent calculations. There are methods to suit the most demanding situations, including the case where the sag is greater than the structure height, which can occur in rugged. mountainous terrain.
Sag Calculator comes with extensive, context sensitive, on-line help with practical advice regarding the advantages and disadvantages of each method.
With Sag Calculator, you can even sag spans where one or both of the supporting structures have been moved during construction but the sagging schedule is not up-to-date.
Sag Calculator allows you to vary any input parameter to see how sensitive the output parameter is to this change. This will give you a feel for the degree of control that you exercise with each method.
The time saving methods allow more spans to be sagged than would traditionally be sagged using the sight board method. This means that the constructed tensions will be much closer to their design values, thus ensuring statutory ground clearances are met.
Each variable used in the calculations is saved in the event of a future audit requiring resolution of a conflict.
Sag Calculator stores the data for each cable (phase, subconductor, earthwire or pilot cable) that is sagged or checked within each span. A project file would normally be setup for each feeder that is sagged. Provided that structure numbers are unique, one file would suffice for checking sags. However, the tensions do depend upon the conductor type.
A basic report of Actual Sags (check mode) and Required Sags (sag mode) can also be generated by Sag Calculator.
Sag Calculator has been tested against a 36 page written test plan containing more than 350 tests. In addition, Sag Calculator has been independently and thoroughly tested and verified by Ergon Energy Australia.
So far, the program has required in excess of 300 hours of development time, and its source code consists of more than 88,000 lines of Delphi program code.
