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Linked Cables

This post is related to consideration and planning of a set of new features.  Our time frame for implementation is to do this in stages, starting third quarter 2017 and completing early 2018.  Please feel free to contribute and add your views to the discussion.

Cables within myCableEngineering are looked at individually.  This makes the sizing of cables uncomplicated, easy to understand and is the way the majority of our users like to work.  However, some users would also like a more system type approach (being able to calculate the total voltage drop from the source to cable load for example).  One of our design goals is to avoid turning myCableEngineering into just another system analysis software (there are already many available), but to keep it intuitive, straightforward, easy to use and a cost effective way to manage project cables.  To cater for all our users and keep to our design goals, we are looking at the concept of 'Linked Cables'

Linked Cables

If a cable's source designation is the same as the destination designation of another cable, the cables are lined.  This means that the cable being studied is supplied by the other cable, with results from one cable calculation being able to supply the input for the linked cable. To assist with the management of linked cables, a 'Group-by Source' option is available for the schedule so that related cables can be displayed together.

For users not wishing to link cables, they need only ensure the source designation is unique or alternatively manually enter the cable system, voltage and fault details (see below).

Note: to change a cable source designation, the user needs to edit the cable.  Future updates will allow inline editing of certain cable fields directly from the schedule/grid.  This will significantly speed up moving of cables.

This is a proposed feature and not yet implemented.  If you would like to comment on this, please join the discussion.

Important: calculations across linked cables is an advanced feature.  For linked cable calculations, you will need to enable this on a project by project basis.  As changes in one cable may affect other cables, the user has additional responsibility for ensuring that related cables are not adversely affected. 

System & Voltage Drop

The voltage and system information for a linked cable is automatically calculated from its parent cable.  The user does not need to enter any of this information.  However, should the user wish he can switch to manual input and override the calculated values. For linked cables, system wide calculations will be available, and for manually input details only cable level calculations.

Both the voltage drop across the cable, and total voltage drop from the ultimate source to the destination of the cable are calculated.  Both cable and total voltage drops are checked against user set limits.

This is a proposed feature and not yet implemented.  If you would like to comment on this, please join the discussion.

Note: calculations across linked cables is an advanced feature.  For linked cable calculations, you will need to enable this on a project by project basis.  As changes in one cable may affect other cables, the user has additional responsibility for ensuring that related cables are not adversely affected. 

Current Capacity

Sustained current capacity calculations are not affected by the linking of cables.

Note: for a supply cable, it is possible to sum all the loads on it's linked cables to arrive at a load current for this cable.  At present we have no plans to implement this, and feel that the user specifying the cable load value is better engineering practice.  However, should there be sufficient demand, it is something we could look at.

Fault Levels

A linked cable's fault levels are derived from the destination fault levels of the supply cable. The user is still able to adjust the fault clearance times (as this information resides outside the application).  The user has the option of overriding the derived values and manually inputting the fault levels he wishes to consider for the cable. 

This is a proposed feature and not yet implemented.  If you would like to comment on this, please join the discussion.

Special Cases

myCableEngineering is not a system analysis application and does not use load flow or numeric solutions.  We rely on circuit theory for our results.  This can create issues where two or more cables supply a single linked cable. Under these conditions, we make the following assumptions:

  • For each supplying cable the destination voltage and fault levels will be calculated:
    • source voltage at the linked cable source will be taken as the lowest voltage calculated
    • source fault levels at the linked cable, will be taken as the maximum levels calculated

The designer having a more detailed knowledge of how the overall system works is free to enter more appropriate voltage and fault levels if necessary. 

This is a proposed feature and not yet implemented.  If you would like to comment on this, please join the discussion.

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