Def Stans - The Ultimate All Rounders
The ‘Defence Standard’ or ‘Def-Stan’ as it’s more commonly known is one of the most popular cables around. Originally developed for military and defence applications it has now become increasingly popular in the commercial industry. There are many different Def-Stan cable standards, however, this blog will focus on the most commercial and versatile of them all - Def-Stan 61-12 Parts 4 & 5. It will look at the range of options available, the differing sizes, screening and sheath options, and some of the applications where they’ve been used very successfully.
Conductor Sizes
The cable is available with either 7 or 16 strands. The strands are always made from tinned copper and cover three different sizes of conductors:
7/0.10mm: This is the smallest available coming in at 0.05mm². It has a current rating of 0.25amp and is used for small electrical equipment with short run lengths.
7/0.20mm: Probably the most popular conductor size at 0.22mm² with a current rating of 1amp. Applications include automated processing, alarm systems, and door entry.
16/0.20mm: This is the largest of the commercially available sizes. It’s 0.50mm² and runs up to 2.5amp. Again, it’s used in door entry and building management (BMS) systems, as well as process control, security, and data transfer.
Insulation
These Def-Stan cables either have PVC or Low Smoke Non-Halogen (LSNH) insulation. The insulation material itself should match the outer sheath material (see ‘Sheath’ below). If the product is being installed in a public building the advice is always to use LSNH as standard for safety. However, if it’s being used on process automation equipment PVC should be fine because of its superior flexibility.
Cores and Colours
These types of Def-Stan cables come in a variety of core counts, starting with the smallest 2core up to 36core. A 50core is available but it’s not widely available. Having so many core options give the installer the peace of mind that they can order any variety and know they have enough terminations with a single cable. The core identification is also simple. Each core has its own colour, with no small numbers to read that otherwise can result in identification mistakes, and every core up to 36 has a different colour. This means that termination is trouble-free.
Screening
There are three different screening options for this type of Def-Stan cable. Your choice should be made based on the application. Does it need a screen at all, or will it be run next to other cables or equipment emitting electromagnetic signals?
Unscreened - Type A
These cables have no screen in them and therefore cannot reduce electromagnetic interference from nearby electrical equipment. These types will be the most flexible and most competitive pricewise.
Braid Screen - Type C
This cable has an overall tinned copper wire braid (TCWB) screen. It’s important to recognise the difference between different manufacturers cables though, as sadly it’s not uncommon to replace some or all of the braid wires with aluminium or a mixed metal of copper and aluminium. This will impede the cables’ ability to reduce external electrical signals, and because aluminium is weaker than copper it’s prone to breaking when flexed. Webro only use tinned copper wire braids to ensure that the cable conforms to standard and performs how you would expect it to, delivering trouble-fee installation and operation.
Foil Screened - Type S
The most popular screen type in alarm, security, and BMS applications, this version has an overall foil screen with a 120% minimum coverage. This ensures that the cable can block external electrical signals, is able to flex better than a braid screen, and is competitively priced.
Sheath
As stated above it’s always best to match insulation material with sheath material on these cables. PVC is generally suitable for process control or industrial control applications because it remains flexible and easy to route. On the other hand, LSNH materials are good for BMS, access control, and door entry applications as well as any other when safety of people is important. The cable is easy to strip in both PVC and LSNH and comes in black as standard with other colours available.
If your application requires a more rugged cable then these can be offered with an extra jacket in polyethylene (PE) so that they can be installed externally or run through ducts. For added protection from rodents or vandals the cable can be armoured using steel wires and then PE sheathed to ensure that they’re waterproof and suitable for direct burial. This then helps to retain all the benefits of the standard Def-Stan cable.
Def-Stan Coding System
The Def-Stan coding system couldn’t be easier for making product selection simple. It consists of numbers separated by dashes and then the screen code:
- The first number is the number of strands, i.e. 7 or 16
- The second number is the strand size, i.e. 1 for 0.10mm or 2 for 0.20mm
- The third number is the number of cores
- Finally, it’s followed by the screen type, denoted by either an ‘A’ for unscreened, ‘C’ for braid screened or ‘S’ for foil screened.
Example: 7-2-12C is a 7/0.20mm (0.22mm²) Braid Screened 12core Def-Stan; all you need to confirm is the material type.
Once a mainstream product of the UK military and defence, Def-Stan cables have made the transition to commercial industry with great success. From wiring a simple alarm panel to a fully automated process control system, these cables still impress today with their vast number of uses.
Find out more by exploring the full Webro Def-Stan product range. Contact our technical sales team on 0115 9724483 or sales@webro.com, or Get in Touch.
