This section provides extensive information on established installation and maintenance techniques that will result in optimum performance.
It is available as a separate publication for issue to installation and maintenance staff as required.
The section covers most of the issues which will confront the installer and maintenance staff when dealing with cables for force guided applications.
Correct transportation, storage, and handling of the cable are most important to avoid damage. It is also important to follow specific cable installation procedures to avoid torsion and other undesirable mechanical effects during installation.
The summary of compatible connectors, terminators, plugs, couplers, splice kits, etc. which is given in this section is intended to serve as a guide for the user.
It is not intended that this guide precludes the use of alternate materials or techniques, nor do we accept responsibility for third party materials.
For best results, confirm the compatibility of the selected accessory for the intended application with the manufacturer or his representative and follow his instructions with care.
Prysmian power cables are manufactured with a left hand conductor lay. This conductor lay has the natural effect of making the cable roll to the left. It is therefore important that the first turn of cable be installed on the drum or random wound reeler against the reel's left hand flange and angled correctly. This allows the cable to layer on the drum correctly. Prysmian control cables, with their right hand lay, should be installed in the opposing direction.
To assist in the movement of the cable over guide rollers, sheaves, etc., a dry lubricant or silicone based grease may be used. These types of lubricants resist grit and dust from adhering to the lubricated surface.
The preferred method for on site cable installation is to jack up the transport reel and unwind the cable onto the cable run along the entire length of the machine's travel route. Conventional cable pulling equipment and rollers can be used for this purpose. If the marking or jacket imprinting on the cable shows a slight spiraling around the cable along its length, do not attempt to straighten the cable. The spiraling is a natural effect of the manufacturing process, which is sometimes evident over long cable lengths.
In many cases, this procedure cannot be used due to site conditions. Direct transfer of the cable onto the reel can be used whenever long runs of large diameter cable are installed. This method also is recommended when the reel location and/or cable runway are not accessible.
Avoid introducing "S" bends between the transport reel
and the reel during this procedure. Whenever possible, the cable
should be transferred directly from the transport reel onto the
reel without passing over any guide rollers or changes of direction.
The transport reel-to-reel transfer should be performed slowly and with a minimum of tension to avoid torsional influence on the cable during installation. The machine should be taken to the end of its travel and the anchor point released if detectable torsion is evident during installation.
Correct installation and maintenance of cable tender systems is essential for reliable performance. For general guidelines on transport reel handling please click here.
Generally, high operating speeds require tenders to be used with multiple cable installations. Therefore, it is important to balance the system as well as possible. The steel wire towropes must be adjusted correctly to avoid application of excessive tension on the cable. Adjustment can be made to allow more tension to be applied to the heavier power cables than to the lighter control cables by adjusting and maintaining cable length. This procedure must be carried out carefully so that sufficient tension remains on each cable to prevent it from leaving its sheave during operation. Follow equipment manufacturer's instructions for detailed installation and maintenance procedures.
Steel wire rope has a tendency to increase in length shortly after being placed into service. When this occurs the pulling force can be exerted entirely on the electrical cables. It is therefore important to check the steel wire rope as per the cable tender manufacturer's instructions and adjust it accordingly.
The optimization of pulling tension between the steel wire rope and electrical cables is important as cables that are too loose can be cut by the cable tender.
Generally when cable is installed onto a forced
guidance system, i.e. reeler, festoon system, gravity fed
(spreader) basket, etc., the transport reel should be jacked
up above ground level. Avoid introducing "S" bends.
Advice for specific types of guidance systems follows the
notes on twist removal.
When installing festoon systems, do not over tighten the clamps on the trolley saddles. The clamps must be tightened sufficiently to prevent any cable slippage during operation, which would result in uneven loop depths. Over tightening the clamps leads to stress concentrations at the clamping point. This condition can cause cable failure, particularly with high-speed systems.
A wide range of flat and round cables in assorted sizes may be used on festoon systems, and a multitude of different clamping systems are available. Only general guidelines are available for clamping pressures. Basically, the clamp should be tightened until slight cable deformation is evident to provide adequate clamping pressure. A quick means of visual inspection for cable slip is to spray paint the clamp and cable on the trolley.
Clamps used to hold the grouped cables should be tightened with sufficient pressure to retain their position. The clamps should be tightened firmly to the heavier and stronger power cables only. This condition should allow the control cables and others of less strength to slip through the clamp, eliminating excessive mechanical stresses on the lighter cables.
Particularly with large, fast moving festoon systems in which multiple saddle trolleys or cable stacks are used, establish the correct loop depths and clamp locations. This should be accomplished during initial installation and maintained in their correct relative positions during the life of the system. The ideal installation places lighter control cables on the bottom saddle or stack with a long loop depth. The power cables should be on top with a shorter loop depth. The towrope should be the shortest component in the loop.
This loop relationship ensures that the strongest cables will absorb tensile forces when the festoon system accelerates apart, protecting the lighter control cables from undue tension. A clamp inserted firmly around all cables at the bottom of the loop defeats the purpose of the system. Therefore, it is necessary to locate clamps about 1/3 of the loop depth from the bottom. They should be offset slightly so they do not strike one another when the festoon loops close in the parked position. Because of their susceptibility to wind sway as a result of their large sail area, the use of clamps on flat cable systems is recommended.
Under high wind, or icing conditions, round cable is preferred to
flat. This is to ensure that the flat cable will not be damaged
due to "sailing" or excessive weight due to ice build
up on the cable. If flat cables are used in high wind areas or on
high-speed systems a maximum loop depth of 10ft (3m) should be maintained.
For towropes, wire ropes are preferred to steel chains, as chains
may tangle with the loop clamps pulling loops out of alignment.
Generally, no special termination materials or cables are required for fixed connection of cables of 2000V or less. Crimp type lugs and connectors (glands) to execute fixed connections in weatherproof enclosures are readily available to cover almost all items listed on these pages.
However, the special considerations applicable to force guided cables have led to a variety of different termination techniques becoming established as follows.
The wide variety of options available to the user precludes us from listing all possible types of terminating equipment applicable to the range of cables covered in this material.
However, in order to assist the user who has no preferred procedure or source of supply, we have attempted to describe and cross-reference (where possible) all commonly available termination techniques.
In order to provide effective assistance we have identified market-leading products by name and/or part number. This does not imply an endorsement of any product mentioned nor does it preclude in any way the use of other products. This information is intended only as a guide and it is the user's responsibility to confirm the compatibility of any equipment selection with the given application.
General guidelines given in this catalog are not intended to supersede the manufacturers' instructions given with terminating materials. For best results confirm the compatibility of selected equipment with your preferred supplier and follow their installation instructions with care.
As
the force-guided cable is often used in applications where the cost
of downtime is prohibitive, a quick disconnect feature to allow
fast replacement of a damaged cable is often an operational requirement.
Where installed below ground level, such plugs may be subjected
to ground water or tidal influence.
Correct sealing and filling compounds should be used to enhance performance under these conditions.
Plugs and couplers are available from a number of manufacturers and are generally divided into power and control categories.
Typically available power cable couplers include brands such as TJB, Joy and PLM and are specifically designed for heavy duty mining applications. Such couplers may be used for CORDAFLEX (K) and CORDAFLEX (SM) cables, particularly in the larger power sizes to enable fast replacement of damaged cable.
For control cable conductor counts and sizes, the market leading brands include CamLok's series 2001, Pyle National's Star-Line series and Crouse Hinds.
These types of plugs are often used with spreader cables such as SPREADERFLEX and CORDAFLEX (SM) (RS) but are also suitable for applications covering the full CORDAFLEX (K) and CORDAFLEX (SM) control cable line.
For further information or cross-reference, please contact your nominated plug manufacturer or your nearest Prysmian sales office or distributor.
Cables
being utilized for push button pendant station control of cranes
are exposed to static loads due to the weight of the vertical cable
plus the weight of the pendant. Furthermore, excessive tensile loads
may be applied to the conductors if the cable is used to pull the
crane along its track. The cable is also subjected to torsional
forces in a free swinging application. Both factors contribute to
reduce cable life.
Proper stress relief of pendant station cables can be accomplished by the use of either Kellems® grips or a steel messenger rope attached from the pendant to the crane structure. The cable should be looped at the crane end to offer additional relief from tensile forces. Please click here for information on "Anchoring with a Kellems® grip". If a steel messenger rope is used, the cable should be clamped to the messenger at three feet (1 meter) intervals.
Whenever
possible, use a fork truck or crane to lift the transport reel.
Avoid, or at least minimize, rolling the reel on its flanges. If
rolling is necessary, always roll in the direction of the arrow
shown on the reel's flange.
Observing these suggestions will keep the cable coils tight on the reel and prevent any torsion or tension from acting on loose coils of cable.
Another
recommendation is to store reels of spare cable on their flanges
to prevent slumping cable coils. This should be considered whenever
long term storage of operating spares is anticipated.
Spare or back-up cables that may require long term storage should be kept in a cool and shaded location to prevent a "set" from developing in the cable. The cable's ends must be sealed to prevent ingress of moisture and storage should be in a dry location.
Correct
handling of the cable and spare cables is necessary for reliable
SPREADERFLEX cable operation in spreader baskets or tubs.
To eliminate the need for unreeling and re-reeling when adding connectors, SPREADERFLEX can be ordered, "joy wound" onto a special shipping reel. A "joy wound" reel provides access to both ends of the cable while it remains on the reel. There is a service charge for joy winding SPREADERFLEX.
Directly feed the cable into the spreader basket in a counter-clockwise direction from the top of the transport reel.
No twisting of the cable should be induced while it is fed into the basket.
The polyurethane
jacket of the SPREADERFLEX cable has a high resistance to oil and
grease. This characteristic permits most common lubricants to be
used on the basket and guide equipment for trouble-free operation.
The cable should be lubricated to ensure correct coiling into the
basket.
One lubricant which has provided good operational results is Neva Melt grease by Drew Chemical Corp., Magnus Maritic Division, of Boonton, New Jersey. Lubrication is best performed immediately after installing the cable. Click here for basket design recommendations.
Above 300 fpm hoist speeds occasional "backwrapping" of cable as it enters the basket may be observed. This is normal in many cases and will not damage the cable. Modification of the spreader basket or other changes may be necessary if the cable entry into the basket becomes excessively troublesome.
Test hoist the spreader several times immediately after installation. The testing is necessary to ensure that the cable is coiling correctly prior to termination. It is usually immediately following installation that any problems of torsion build-up can be detected.
In the course of operating a gravity fed collector basket system, the jacket may be accidentally cut or nicked. If this should occur, the jacket must be repaired immediately even if the insulated conductors are still intact.
This is because the twisting imposed on the cable will cause the conductors to try to "migrate" out of the cable through the cut jacket leading quickly to cable failure. Even where the jacket is significantly weakened, but not cut through, "bulging" caused by migrating conductors may begin to develop.
In the event of jacket damage as described above, the key is to restore the circumferential strength of the damaged portion to at least that of the undamaged cable. Conventional self-adhesive PVC tape will not give adequate results. The use of fiberglass reinforced tape is recommended, as this will provide maximum strength without over sizing the repair. The tape wraps should be tapered towards the ends so that there is no tendency to catch on the basket guide. For best results, finish with an outer wrap of PVC tape and lubricate the taped area before returning to service.
Cables
in power tracks should be installed parallel to each other and have
sufficient length to allow full movement of the cable while the
power track is in motion. This will ensure that the cables do not
experience tensile load.
Lightly tightened cable ties should be used to attach the cables inside the power track. Care should be taken to maintain cable alignment when installing the cable ties.
Flat cables may be stacked in the power track prior to attachment with cable ties. Round cables may also be stacked in a power track only if the second layer of cables is placed in the interstice formed between two adjacent cables in the first layer. Lightly tying the cables together in bundles of three with cable ties is recommended.
In the event that the cable has become twisted during the handling described previously, the following practices should be used.
Two common methods of twist removal are recommended. The first utilizes a wave motion whereby a cylinder roller between 6 - 8 inches in diameter is inserted underneath the cable near the detected twist. Two people should then walk with the roller and push the "wave" towards the free end of the cable. This procedure should be repeated until the detected twist is removed.
The spiral method can be carried out by one person to achieve the
same effect as described above. Enough cable should be provided
at the cable's fixed end to make a spiral on either the left or
right hand side depending on the direction of the twist. The spiral
is then rolled to the free end of the cable thereby removing any
twisting. This process may need to be repeated to remove all twists
in the cable. The cable may then be re-anchored to start operation.
