ALCO Cable Gland Tutorial

Transcription

1 ALCO Cable Gland Tutorial Selection and fitment of Hazardous Area SWA Cable Glands Phone:

2 Steel Wire Armoured Cable Consider the construction of SWA cables, starting at the outside diameter (OD) There is a PVC or XLPE sheath that covers the entire cable that is required to have an environmental seal. Underneath that covering are protective steel wires that are wrapped around the rest of the cable build to provide flexible/mechanical protection as well as a current path to earth for fault protection via the SWA grounding cones. Underneath the steel wires, there is another protective sheath that also requires an environmental seal. Under this sheath sometimes finds additional brass tapes or a nylon jacket. The balance of the cable build is made up of the insulated conductors which are electrical terminated to carry the required load. In Hazardous area fitment, the requirement of the gland is not only to provide tortuous path, earth bonding of the SWA and environmental sealing, But to also consider seal dimension and characteristics as well as special thread dimensions to provide managed expansion of air pressure or gas pressure from one environment to another.

3 Gland Selection It is imperative that the correct cable gland to suit the fitting environment is selected. Hazardous Areas must have compliant Hazardous Area Glands See the following page or refer to page 2 of the Alco catalogue for classifications. This information is also available online at

4 Hazardous Area Gland Classification

5 HAW and HAW-B HAW Hazardous Armoured gland Termination: HAW Gland Assembly HAW-B Hazardous Armoured Barrier gland Termination HAW-B Gland Assembly In most cases references to explosion proof will pertain to barrier glands.

6 Critical Dimensions for Gland selection Overall Diameter (OD) This is the outside or overall diameter of the cable, where the OD seal will fit. SWA Diameter This is the individual diameter of the protective steel wires in the armour. Over Bedding Diameter (OB) This is the diameter of the insulation, underneath the SWA. Under Bedding Diameter This is the diameter underneath the bedding but over the sheath covering the multicores, where the OB seal will fit.

7 Critical Dimensions for Gland selection It is necessary that each cable is check measured prior to fitment of glands due to manufacturing inconsistencies in the dimensions of cable. It is quite common for cables to be +/-1 or 2mm different than catalogued sizes. Dimensions from the beginning, middle and end of a drum can vary as can the diameter from one batch over many cable drums.

8 Critical Dimensions for Termination In each case, HAW or HAW-B, there are dimensions quoted in the relative gland tables for exposed lengths of SWA and bedding. Arbitrary or random SWA lengths cause a lot of trouble at termination, so adherence to the quoted dimensions is critical. i.e. If SWA is left too long then there will be issues trying to fit the sleeve, affecting the seal on the bedding and OD.

9 HAW GLANDS Typically this style of gland not only offers IP68 weather protection but also offers tortuous path or mechanical securing and earth bonding of the Steel Wire Armour. In addition to the primary function of this gland is the suitability to Hazardous area fitment. Flame path threads and seals are different to the normally used AW gands.

10 HAW Gland Table

11 HAW Hazardous SWA Establish the suitable HAW Gland for the termination application. In the sealed packet there will be 1 seal to suit the OD of the cable. Also there will be two seals, A and B to suit a flexible range of OB dimensions for that gland. Establish the correct seal to use and discard the other. Also discard the brass cone insert as it is not used in this application.

12 HAW Assembly

13 HAW Gland Assembly 1. Pass the Gland nut and OD seal over the end of the cable to be terminated. 2. Determine the length of the tail, removing the sheath with a cable knife or Jokari stripper 3. Remove the SWA leaving the required exposed length determined from the gland instruction sheet (Dimension E ). 4. Pass the sleeve and clamping ring over the SWA and then slide the cone over the bedding and under the SWA. You may need to pre-bend the SWA to do this with smaller size cables. 5. Screw the body of the gland into the enclosure by screwing into the tapped thread for fitment. Ensure the fibre washer provided is used to retain the IP68 and EX rating.slide the appropriate inner seal over the bedding and ensure it is butted up to the cone. 6. Slide the cable through the fitted gland body, ensuring that the SWA butts up against the cone face.

14 7. Maintaining pressure, so that the inner seal, cone and armour remain in place, slide the clamping ring, and sleeve against the SWA and tighten. 8. Slide the OD seal into the fitted gland assembly. Apply a small amount of cable pulling lubricant onto the exposed surface of the OD seal to allow for easy assembly when the gland nut is now pushed up to meet the threads of the gland assembly. 9. Tighten the gland nut as per specifications supplied. These instructions are also printed in the Alco Gland Catalogue and are also available on the website;

15 HAW To B or not to B Barrier glands are typically used in applications where standard glands featuring elastomeric seals are insufficient. Barrier glands are similar to standard hazardous area cable glands, except an epoxy compound sealant (insulputty) is required to be used to seal around the individual cores and the gland. This is done to ensure the inside and outside of the cable remain liquid tight. Furthermore, the following questions need to be answered to establish whether a barrier gland is required.

16 Is the cable round, compact and effectively filled? Yes-> move to next question No-> barrier gland is required Does the enclosure have an internal source of ignition? Yes-> move to next question No-> standard gland may be used Does the hazardous gas require IIC apparatus? Yes-> barrier gland should be used No-> standard to next question Is the installation area zone 1? Yes-> move to next question No-> standard gland may be used Is the volume of the enclosure greater than 2 litres? Yes-> barrier gland should be used No-> standard gland may be used

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18 HAW-B GLANDS In addition the primary function of this gland and its suitability to Hazardous area fitment, application of epoxy putty can be applied between the cores of a multicore cable to ensure the integrity of the flame path. This is important where in cable construction, the inner cores do not allow for symmetrical or regular diameters for ordinary seals to fit well.

19 HAW-B Gland Table

20 HAW B Hazardous SWA BARRIER Establish the suitable HAW-B Gland for the termination application. In the sealed packet there will be 1 seal to suit the OD of the cable. Pay particular attention to the dimension Under bedding, that is over the multicores. Discard the OB seals as the brass cone insert is used in this application.

21 HAW B ASSEMBLY

22 HAW-B Gland Assembly 1. Pass the Gland nut and OD seal over the end of the cable to be terminated. 2. Determine the length of the tail, removing the sheath with a cable knife or Jokari stripper 3. Remove the SWA leaving the required exposed length Dimension E determined from the gland instruction sheet. 4. Trim the bedding so that the exposed length beyond the SWA equal to dimension G determined from the gland instruction sheet. 5. Spread the exposed cores of the cable and remove any fillers or tapes without damaging the insulation on the conductors. 6. Pass the sleeve and clamping ring over the SWA and then slide the cone over the bedding and under the SWA. You may need to pre-bend the SWA to do this with smaller size cables. 7. Screw the body of the gland into the enclosure by screwing into the tapped thread for fitment or by use of a locknut. Ensure the fibre washer provided is used to retain the IP68 and EX rating.

23 8. The epoxy filling compound is a two part product that must be thoroughly mixed so that it has an even colour. Where larger glands are supplied with multiple packets of compound, mix each pack separately and then apply collectively whilst all fill is pliable in one application. The compound has a working life of around 40 minutes at ambient temperatures of 25 degrees. Use of the supplied disposable gloves is not essential however, is recommended for those with sensitive skin or where prolonged exposure is anticipated. Mix the epoxy compound. 9. Pack the compound between the exposed cores starting at the centre and working outwards, for the length of cable equal to the length of the supplied brass insert. Ensure that as you work the epoxy compound inwards to outwards, the cable cores return to their original position and all are fully coated with the compound. Additionally ensure there is sufficient compound to completely fill the bell shaped end of the brass insert. 10. Slide the insert over the epoxy filled cores, removing excess compound as required, until the brass insert mates onto the cone. 11. Slide the cable through the fitted gland body, ensuring that the brass insert remains mated with the cone and that the SWA butts up against the cone face.

24 12. Slide the clamping ring and sleeve onto the SWA. Tighten the sleeve whilst ensuring that the SWA is not allowed to slip back from the cone face or that the brass insert does not part from the cone during this tightening process. 13. Slide the OD seal into the fitted gland assembly. Apply a small amount of cable pulling lubricant onto the exposed surface of the OD seal to allow for easy assembly when the gland nut is now pushed up to meet the threads of the gland assembly. 14. Tighten gland nut as per specifications supplied. 15. Leave the assembled gland for three hours to allow for the epoxy compound to cure. After curing, the gland may be disassembled for inspection or maintenance. These instructions are also printed in the Alco Gland Catalogue and are also available on the website;

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26 ALCO Cable Gland Tutorial Thankyou! For your attention Phone: