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:

cable length = head length + route length + tail 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.

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:

head length = base length, measured as dx + dy + dz

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

head length = base length + Additional head and tail length from cable router settings

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:

head length = base length + Extra length at head from cable's properties

Route length

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

route length = base length, measured as Σ (length of segments)

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

route length = base length + Additional route length from cable router settings

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:

tail length = base length, measured as dx + dy + dz

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

tail length = base length + Additional head and tail length from cable router settings

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:

tail length = base length + Extra length at tail from cable's properties

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:

directly routed cable's length = base length, measured as dx + dy + dz

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:

directly routed cable's length = base length + Additional route length from cable router settings

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:

directly routed cable's length = base length + Additional head and tail length from cable router settings

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:

directly routed cable's length = base length + Additional route length + Additional head and tail length from cable router settings

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:

directly routed cable's length = base length + Extra length at head + Extra length at tail from cable's properties

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.

Attribute	Tag	Description	Availability
Length	len	This value represents the total length of the routed cable as stored in COS and including all extra head/tail lengths defined in the cable router. The value is expressed in millimeters.	Available in listings and via the Query Cable tool.
Length	cle	This value represents the total length of the routed cable as stored in COS and including extra head/tail lengths defined in the cable router. The value is expressed in meters.	Available in the columns of the cable router and in listings.
Changed cable length	.L2	This value represents the total length of the routed cable as calculated from its current route, including extra head/tail lengths defined in the cable router. For changed cables, this shows the new length, which may differ from the previously stored length (cle). For unchanged cables, this usually matches the stored length (cle). There may be a small difference if some of the route nodes have been moved by less than 75 mm, which is not enough to designate the cable as changed but enough to affect its length. For cables with a broken route, this is not calculated. The value is expressed in meters within the cable router, but in millimeters elsewhere.	Available in the columns of the cable router, in listings, and via the Query Cable tool.
Cable extra length at head	.np	Shows either "Using cable settings (<value> mm)" or a cable-specific extra head length defined by the user. The value is expressed in millimeters.	Available in the columns of the cable router, in listings, and via the Query Cable tool.
Cable extra length at tail	.nq	Shows either "Using cable settings (<value> mm)" or a cable-specific extra tail length defined by the user. The value is expressed in millimeters.	Available in the columns of the cable router, in listings, and via the Query Cable tool.
Cable head length	.Gm	This value represents the length of the head of the cable, as stored in COS and including the extra head length that may be defined in the cable router. The value is expressed in millimeters.	Available in the columns of the cable router, in listings, and via the Query Cable tool.
Cable tail length	.Gn	This value represents the length of the tail of the cable, as stored in COS and including the extra tail length that may be defined in the cable router. The value is expressed in millimeters.	Available in the columns of the cable router, in listings, and via the Query Cable tool.
Cable length to the penetration from head	.Go	This value represents the length of the cable from the head equipment (or virtual point) to the first penetration component in the route, as stored in COS. The value is expressed in millimeters.	Available in the columns of the cable router, in listings, and via the Query Cable tool.
Cable length to the penetration from tail	.Gp	This value represents the length of the cable from the tail equipment (or virtual point) to the last penetration component in the route, as stored in COS. The value is expressed in millimeters.	Available in the columns of the cable router, in listings, and via the Query Cable tool.

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