Cable length calculations

When Plant Modeller needs to know the length of a particular cable, such as the overall length of a cable route or the amount of cable that should be delivered to a cable pulling location, the length calculation takes into account how the cable is routed, and what kind of extra length values the user has defined.

Normally, a cable starts from a piece of equipment, is routed via the cable ways, and ends at another piece of equipment. Such cables have three main constituents that define their overall length:

In this calculation, each individual length value can consist of a base length and possible extra length defined by the user.

There are a number of extra length settings that the user can define to make sure that enough cable is reserved for installation:

• All cable routes can get extra length from the cable router setting Additional route length (see Cables), if it has been defined:

  route length = base route length + additional route length

• All cable ends (heads, tails) can get extra length from the cable router setting Additional head and tail length (see Cables), if it has been defined:

  head or tail length = base head or tail length + additional head and tail length from cable router settings

• To override the cable router setting, an individual cable end can use the Extra length at head or Extra length at tail value from the cable's properties (see Set extra lengths), if either value has been defined:

  head or tail length = base head or tail length + additional head or tail length from cable's properties

On the other hand, a cable that goes directly from one equipment to another has no base route length, so its length is calculated differently than that of a cable that goes through cable ways. This, and other special cases, are described in more detail below.

Note: The extra length information is not stored in the cable; the extra lengths are calculated whenever length information is requested from the program.

• Cable length calculations
  • Head length
  • Route length
  • Partial route length
  • Tail length
  • Length of a directly routed cable
  • Length from head to first penetration
  • Length from tail to last penetration
  • Length from head to pull marker
  • Length from tail to pull marker
  • Length related cable attributes

Head length

The base length of the head section is the distance from the head equipment to the first node, measured along the main axes X, Y, Z:

If additional head and tail length is defined in the cable router settings, the value is added to both ends of the cable:

If the user defines extra head length for an individual cable, the value is added to that specific cable, instead of using the common head and tail value from cable router settings:

Route length

The base length of the cable route is the combined length of the cable routing network segments that the cable uses:

If additional route length is defined in the cable router settings, the value is added to the route:

Partial route length

A partial cable route only has a base length—all extra lengths are managed by the main cable route. When a partial route includes head or tail length, this is included in the main route length if the corresponding routing point is real. If the routing point is virtual, the head or tail length is not included.

In a partial cable route, a routing point is considered virtual if the main cable route can bypass that point using a segment. In cable penetrations, routing points are always considered virtual because there is a penetration segment that bypasses them.

A partial cable route can be a direct route from head equipment (or routing point) to tail equipment (or routing point). In direct partial routes, the routing points are always real—not virtual—and the partial route length affects the main route length. Direct partial routes do not have head or tail lengths.

Both real and virtual routing points can affect the following cable lengths:

• Length (cle) or Length (len), indicating total cable length

• Changed cable length (.L2)

• Cable route length from pull marker to head (.C5)

• Cable route length from pull marker to tail (.C6)

• Cable length to the penetration from head (.Go)

• Cable length to the penetration from tail (.Gp)

Note: The length of a main cable route is not accurate until all its partial routes are defined.

Tail length

The base length of the tail section is the distance from the last node to the tail equipment, measured along the main axes X, Y, Z:

If additional head and tail length is defined in the cable router settings, the value is added to both ends of the cable:

If the user defines extra tail length for an individual cable, the value is added to that specific cable, instead of using the common head and tail value from cable router settings:

Length of a directly routed cable

Cables do not have to go via the cable ways. When two pieces of equipment are located in the same 3D space, it is possible to route the cable directly from one equipment to another.

The base length of a directly routed cable is the distance from the head equipment to the tail equipment, measured along the main axes X, Y, Z:

If additional route length is defined in the cable router settings, the value, which can be defined in millimeters or as a percentage, is added to the directly routed cable:

If additional head and tail length is defined in the cable router settings, the value, which must be defined in millimeters, is added to the directly routed cable:

If both additional route length and additional head and tail length are defined in the cable router settings, both values are added to the directly routed cable:

If the user defines extra head or tail length for an individual directly routed cable, the values, which must be defined in millimeters, are added to that specific cable, instead of using the head and tail value from cable router settings:

Length from head to first penetration

The program calculates the cable's length from the head equipment to the first penetration component in the route.

Length from tail to last penetration

The program calculates the cable's length from the tail equipment to the last penetration component in the route.

Length from head to pull marker

The program calculates the cable's length from the head equipment to the pull marker node.

Length from tail to pull marker

The program calculates the cable's length from the tail equipment to the pull marker node.

Length related cable attributes

The various length measurements are available in the following attributes.

Attributes that show the cable's length on each side of the pull marker node are described in Pull Markers.