ClampStar is designed to carry more current than the largest conductor which a given unit will accommodate, i.e. no limitation to the user, and are suitable for use at the maximum conductor temperatures specified by the conductor manufacturer, continuous operating temperatures, emergency temperatures, or otherwise. Tests performed by CCI and others indicate the largest conductor (aluminum stranding) will fuse before the ClampStar sustains any damage. As the industry has not yet set a “standard” for evaluation of connector performance on High Temperature – Low Sag Conductors, we have chosen ACSS as the maximum temperature model, specified by the manufacturers as suitable for continuous operation at 250C conductor temperature (assumed measured at the surface – as this is not yet specified either). Based on testing such applications for a minimum of 500 thermal cycles with the ClampStar serving as a connector (carrying 100% of the electrical load) at conductor temperature of 390C, which we deem an equivalent percentage of thermal induced stress in comparison to the long established ANSI C119.4 Class “AA” test protocol, Extra Heavy Duty, said test being performed for the purpose of indicating stable performance of a connector installed on “service aged” conductor.

All ClampStar connector correctors are guaranteed to hold a minimum of 60% (C119.4 Class 1A Normal Tension) of the rated breaking strength (RBS) of the largest and strongest conductor within its clamping range when tested alone, without a primary connector in place. (See notes [a] and [b] below).

There is normally a connector in place, carrying line tension (even if degraded) at the time ClampStar is installed. ClampStar immediately shunts the majority of phase current around the degraded device, thereby reducing its temperature to near ambient, preventing further degradation, and halting any slip that may have occurred. The combination will restore a Class 1 Full Tension rating to the installation.

ClampStar is not intended to be a primary connector, but is designed to operate in conjunction with a primary connector, such as a splice or deadend, to reinforce the primary connector and restore its electrical and mechanical integrity to its original condition, or to exceed that condition.

As is the case with all bolted connectors and strain clamps, because ClampStar utilizes threaded fasteners, and is installed over a conductor, directly engaging only the outer layer of stranding, mechanical performance varies with the type of conductor. A full explanation of this is included in the PDF document titled: “Understanding the Mechanical Performance of ClampStar.”

(Note [a]: This 60% is based on ACSR type conductor. AAC, AAAC, and ACAR will typically approach “full tension” ratings).

(Note [b]: ACSS, ACCC, ACCR, INVAR, Gap Type, SD Type conductors rely on the primary connectors purchase and engagement of the core. ClampStar cannot engage or purchase the core of any conductor, including ACSR, and therefore requires the primary connector to serve as the mechanical anchor).

In its normal application, as a current shunt and a mechanical support for splices and other full tension connectors, there is no tension load on the ClampStar® unit because the connector over which the ClampStar® is installed is holding the tension and the conductor span is already tensioned when the ClampStar® unit is installed. Thus, the ClampStar / primary connector combination continues to maintain a full tension rating.

Similarly, there is no tension load on the ClampStar® unit when it is applied to shunt tangent suspension and other non-tension clamps and connectors.

The only purpose of ClampStar® units having a tension rating is to assure that the ClampStar® unit will continue to support the mechanical load and maintain conductor integrity in the unlikely event a severely degraded primary connector fails mechanically after ClampStar® installation.

The mechanical integrity of bolted line hardware is dependent upon the application as well as the conductor size and construction. This applies to all types of bolted conductor hardware, including straight line strain clamps, quadrant strain clamps, deadend shoes, etc. Like all bolted line hardware, ClampStar® units have two mechanical strength ratings. One is the UTS or Ultimate Tensile Strength of the ClampStar® body. ClampStar® units sized up through 4/0 AWG (CSR-0609) have UTS ratings that exceed the RBS (Rated Breaking Strength) of the largest conductor on which the ClampStar® unit can be used. The UTS of larger ClampStar® units is at least 70% of the RBS of the largest conductor on which it can be applied.

The conductor holding or slip strength is dependent upon the conductor used. ClampStar® Connector Correctors alone are designed to hold at least 60% RBS of the largest and highest strength conductor for which it is designed. However, most applications will exceed that rating and most AA conductors will be held to at least 95% of the conductor RBS, which is considered to be full tension.

Maximum line tension designs under worst case conditions for a given geographical area, are limited to 60% conductor RBS under maximum ice combined with maximum wind conditions. Normal line tensions are on the order of 10 to 25%. For example, a line utilizing 795 Drake ACSR conductor, which has a specified RBS (Rated Breaking Strength) would be normally tensioned to something between about 3000 lbs. to perhaps as much as 10,000 lbs, depending on span length and allowable sag. Thus many utilities utilize bolted deadends, such as inline shoes or quadrant style clamps, of which the vast majority are only rated at 40% RBS, but often test (on a given conductor) to tensions of 60 to 70%.

Exactly like bolted deadends, ClampStar units are designed to obtain a minimum of 60% RBS for a given conductor size, not including the connector already in place. i.e., if two cable ends were terminated in respective ends of a ClampStar, having no connector in between, with the ClampStar holding the entire tensile load, it would be intended for 60% minimum of the largest ACSR conductor which it will accommodate. Typically, it will exceed 70% or more, but being an external bolted connection, like all bolted deadends or other line hardware that has been used for over 100 years, it probably will not reach full tension based on the conductor rating, because it does not directly attach to the core. However, the design and intent of ClampStar is to be applied over an aged connector, that although is undoubtedly weakened due to annealing, is presently supporting the full line tension, and now having been protected from further thermal excursions, will contribute sufficiently to the overall assembly, and thus the repaired assembly with ClampStar included can restore the mechanical integrity to that of the original conductor/connector.

For applications on Dead-ends and suspension clamps, a stainless steel tether cable is available to attach through the steel eye, to assure the mechanical integrity of the assembly.

A mechanical tether is not necessary for splice applications, as the ClampStar is “in-line” with the tensile load and is designed to carry it. The mechanical tether is an option that is available on ClampStars® with flexible cable rails and is primarily intended for use with deadends. It may also be used occasionally on tangent suspension clamps when severe conductor damage has occurred. It is an auxiliary safety cable that is intended to keep the conductor in the air, even if the primary connector fails or completely separates mechanically.

Typical examples for use of a CSF ClampStar over a deadend would be either to uprate the line for higher ampacity, possibly for contingency conditions, or to restore the electrical integrity to a connector which has been identified as approaching failure, commonly by a hot infrared signature, or high resistance measured in-line.

If the purpose is to uprate the line, and the connectors are known to be mechanically sound, once the ClampStar is installed, the connector will be protected, and will remain cool (only slightly above ambient temperatures) and not be subjected to thermal concern, even at significantly high current levels which raise conductor temperatures to 250°C. Therefore, the connector will continue to serve as the mechanical connection to the insulator.

However, if the deadend had been running hot, or was known to have been subjected to severe fault currents, and was severely weakened mechanically prior to installation of the ClampStar, legitimate concern exists for the mechanical integrity of the deadend. Prudence dictates that it can no longer be relied upon to support the conductor, It is in this instance, where a “Safety Tether” may be used. If that deadend should mechanically fail or separate due the the damage which occurred prior to the installation of the ClampStar, the safety tether effectively picks up the mechanical tensile load on the conductor, and maintains near normal conductor position thereby preventing conductor drop, fault, and outage.

Another example would be a conductor with severely damaged strands in the mouth of a tangent suspension clamp. A safety tether from one ClampStar clamp, through the insulator connection of the clamp, to the opposite ClampStar clamp would ensure that the conductor remains in the air if either the conductor or clamp should fail completely.

It’s important to note that tether ferrules are 7/8” diameter (give or take a few thousandths) and will readily fit through a one inch opening. Hardware for deadend tether fittings cannot readily be “standardized” due to the substantial variety of components, not only between different manufacturers, but even from a single mfg. i.e., vertical eyes, horizontal eyes, clevis ends, adjustable clevis ends, and among those, there are different dimensions (such as diameter of cross-section through component) such as 30K insulator hardware, 50K hardware, etc., that it is almost impossible to make a one fits all, or even a 3 fits all.

At the present time we are working diligently with individual utilities to come up with a bracket for their particular application. We will gladly review hardware, and provide a solution for all inquiries.

“Click here to view the recommended ClampStar Safe-T-Link Deadend Installation procedure.”

That is what it is designed and intended to do, up to 20,000 lbs tension (the larger ones on the 1631 and the 1912 will be 30K rated). However, the way it works, (when properly installed with perhaps 1000 lbs of tension on it) is it prevents the deadend from being subjected to any additional tensile force. Imagine, a light cable attached to a screen door extension spring, the other end of the spring fixed, such that the spring mimics the deadend. Now, let’s stretch the spring a little bit by putting 10 lbs of tension on the far end of the cable. Now, let’s take a steel wire, attach it to the point where the spring is affixed, and just beyond the end of the spring, we attach it securely to the cable, in such fashion that the wire is tight, but is not so tight that it takes any significant load off the spring. This represents the tether.
Regardless of how much tension we now put on the far end of the cable, the spring will not elongate, or be exposed to any additional tension until enough tension is placed on the cable to rupture or overcome the wire.

Of course, if the wire is placed in slack, the spring would stretch until the wire became tight. Unfortunately, a deadend would not stretch very much, but it would likely elongate an eighth of an inch or so before rupture if the tether did not stop it. Typically, additional adverse tension applied to the conductor is going to be in the form of ice, or a tree falling on it, which will pull it downward, and thus the tether, properly placed above the conductor in the same vertical plane, will be subjected to the greater tensile force first.

So, the first objective of the tether is to prevent the original connector from ever being subjected to any additional tensile load – just as the first objective of the ClampStar is to prevent the original connector from ever being subjected to any additional ampacity/thermal load. A ClampStar will very effectively limit the temperature of a connector to something below 75˚C, even at ampacity levels that drive the conductor to 250˚C and beyond! The tether will very effectively limit the tensile load to what the connector is subjected to roughly 30-50% of its rated full tension capacity.

If a span were under 10K tension, and the connector was rated at 40K, the addition of the 20K tether would (within reasonable tolerances) prevent the connector from being exposed to 30K of tension, leaving the already existing 30K margin originally in the connector. As the load increases, movement of the conductor toward the ground, and stretch occurring in the tether, the load would likely equalize somewhere around 40K. Beyond that, we would be relying on the 20K margin still available in the original deadend.

The tether on the suspension clamp works in the same fashion, should there be a large percentage of broken aluminum strands, and perhaps even some core strands – more than just “holding the load in case the original conductor breaks” it prevents the area protected in the suspension clamp from ever being subjected to additional tension.

Several customers, from around the globe have brought to our attention, that broken conductor strands due to fatigue are often found under armor rod. It is presently undetermined if the action of the rods may be part of the fatigue problem due to their direct interaction with the conductor strands, nonetheless, this condition is found in both standard saddle type suspension clamps as well as the helical rod suspension systems which incorporate the elastomeric “dog bone” or “hourglass” shaped gripping components under the rods.
The problem is often not detected until conductor failure occurs, because the rods tend to assist in conduction of current, and in so doing, mask the thermal rise which would otherwise be more readily detectable. Thus one might argue that the rods are performing as intended, assuming that fatigue breaks might have occurred earlier had the rods not been in place, and the failure might have occurred earlier. It is difficult to determine the location of broken strands, as they seem to occur in all areas underneath the rods, from close proximity to the clamp, all the way out to nearly the end of the rods with many occurring near the center.

Therefore, the application of ClampStar over suspension systems that incorporate helical rod overlays is recommended to be attached at points directly on the conductor, beyond the end of the rods. Because the ClampStar is attached to the conductor, it moves with it, just as the “clamp portion” of a damper, the added weight serving to disturb the normal wave frequency, and as it has the flex rail attachment, traversing to the opposite side of the suspension system, it transfers a portion of the vibration energy around the normally “fixed point” and dissipates some portion of that energy through the process. Thus by two distinct means, ClampStar serves to dampen the vibration and lessen its severity.

Attaching the ClampStar directly to the conductor assures that (a) the electrical interface will serve to conduct ALL the current in the line if needed with no limits on ampacity, and (b) that should a mechanical need arise, with the addition of a safety tether, the conductor would remain suspended, with almost no detectable differential in sag. In most applications with ACSR type conductor, on normal spans, over cleared right-of-ways, unless there were some concern about the integrity of the core strands, (such as severe corrosion on aged conductor), a safety tether would normally not be required, because the thermal concern will be eliminated by the ClampStar, and the mechanical integrity is unlikely to degrade further. It would perhaps be wise to include a safety tether on “critical” or “high risk” spans such as river crossings, highway crossings, rail crossings, and areas of high pedestrian traffic, where a dropped conductor would cause significant damage or danger. For other types of conductor, such as AAC, not incorporating the safety advantage of a higher strength core, the overall integrity of the conductor must be considered.

The clearance length of the ClampStar is selected by the end user for the application, designated in the part number by the last three digits, i.e. ClampStar CSF-1108-072 is a Flex-Rail ClampStar for conductors typically from just under ¾” diameter up to a maximum diameter of 1.108 inches (795 Drake ACSR); and having 72 inches of clearance between the heads.

Creating a software program to compute the optimal placement of a ClampStar to minimize vibration is extremely complex, as all the mechanical characteristics are not yet quantified. The same may be said for modifying existing vibration analysis software at this time. Therefore, the optimal placement may be slightly different, but at this time, we would recommend placing the ClampStar ends such that the clearance to the end of the helical rods is no less than 3 inches, and typically no greater than 12 inches.

For example, an application of helical rods over 795 Drake ACSR conductor would utilize rods 100 inches long. Thus, an optimal ClampStar for this application would be CSF-1108-112, which would provide 6” clearance beyond the end of the rods.

In order of priority:

1.Type, diameter and size of conductor, i.e., size in kcmil – type, ACSR, AAC, AAAC, ACSS, etc., and preferably with the code name (bird, flower, river, city, animal – or other) from which we can determine everything else. This is needed to determine the proper size of the needed ClampStar, or IF another size might be, could be, or should be substituted. Also an indication for need of tethers. AAC will rarely if ever need tethers, except for deadend or suspension issues.

2. Application! Conductor Damage, Suspension Reinforcement, Connector and Type of splice/deadend; particularly Single Die, or Conventional Two Die, bolted or other. It can be very helpful to get the brand if possible, as this gives a clue to the length, needed to determine the clearance for the ClampStar.

3. Purpose! Is this to repair hot connections, or is this an uprate? Potential application for “Light” versions. Another consideration for tethers.

4. Voltage class of line. Needed to determine corona shielding, and also rigid or flex rail recommendation.

5. Vibration potential – span length – orientation. May determine rigid or flex rail recommendation.

6. Construction of line – single conductor or bundled and how many. Semi-important but could affect shielding options, and gives insight to CSR/CSF as in #4 & 5.

7. Age of the line, if known. May indicate additional potential problems that should be addressed.

8. Operating history, if known. Outages, component failures, other problems.

9. Operating environment. Location, terrain, (sea coast, desert, mountainous, heavily contaminated, etc.).

The basis for ordering CSF vs CSR for splice applications has to do with (a) length, as max CSR lengths are limited to a 40” clearance, but (b) more importantly is the characteristics of the line related to vibration. If the line is prone to high vibration, we would recommend the CSF units, and this is typically related to tension and positions of the span. Short spans of 3-500 feet, typical of some lower voltage applications are optimal candidates for CSR units. Longer spans, 800+ feet are typically best served by CSF units because of their inherent vibration damping characteristics. This is especially important for long spans that are predominantly perpendicular to the prevailing wind direction.

For deadend applications, we would suggest you take a look at the Classic Connectors photo gallery, the first photo is of an improved design specifically for deadends and suspension clamps, which is substantially easier to install, and a few dollars less expensive than the CSF units. It is known as the CSS unit, and should be the first choice for ClampStar applications on deadends or suspension clamps.

First, and most distinguishing, is a “softener – or – cushion” included in the OPGW product. It serves the purpose of evenly distributing the mechanical force of the keepers in a uniform manner such that it prevents crushing of the conductor, and therefore prevents damage to the glass fibers inside their tubular structures.

The OHSW product does not have this feature, and that too is intentional. OHSW units are commonly applied on galvanized steel conductor, which has a high tensile strength, and requires the maximum grip we can achieve, and this is best performed with the individual keepers giving a greater stress concentration to the gripping surface.

Second, again to prevent excessive compression on the OPGW, lower torque shear nuts are utilized. The OHSW on the other hand, utilizes high torque shear nuts to achieve the maximum compression required for the harder steel conductor.

Third, a different inhibitor distribution is used on the respective units.

Classic Connectors recommends that the properly identified product is used in each application, as the design performance of each is substantially different for the specific intended use. Using ClampStar products on conductors not listed within the size range, and conductor type, cannot be warranted. ClampStar® units designed and labeled for use on OPGW and OHSW shall not be used on energized conductors.

ClampStars for higher voltages will be corona-free to at least the corona inception level of the largest conductor for which it is designed. This will be accomplished through a combination of self and auxiliary corona shielding, as required.

Yes they can, and frequently are, for applications above 138 kV. The appropriate shielding is obtained by combining the ClampStar® unit number with the highest anticipated nominal system voltage. Example: corona shield part number CSC-1108-230 designates shielding for corona-free performance of CSF/CSR-1108 units installed on a 230 kV system.

Since most 161 kV lines are insulated for 230 kV, the corona shields for 161 and 230kV are the same and are made to fit specific ClampStar units. If you wish to order a complete assembly consisting of a ClampStar unit and the appropriate corona shields please add a “CORXXX” suffix to the ClampStar unit number. Therefore the complete part number for a unit with corona shielding for a 230kV nominal system voltage would be, for example, CSF-1302-048-COR230.

As noted above the shields for 161 and 230kV are identical for specific ClampStar units, as dictated by the number of keepers and the keeper bolt length. The shields fit over the complete keeper array and keeper bolt ends.

For CSF/CSR-1108 and larger units, 230 and 345 kV corona shields are identical due to the keeper bolt length. They should still be ordered based on the intended system voltage but, if the same ClampStar units are used at 230 and 345 kV, it is only necessary to order 345 kV shielding.

500 kV corona shields are also available.

Shields for 345kV and 500kV will be different [larger diameter tubes].

Note: To ensure that shields are used appropriately at 161kV and above, it is more secure to order ClampStar units complete with shielding when necessary.

Auxiliary corona shielding is only required for units up through and including 1302 (1272 kcmil). Units for larger conductors are self-shielded and require no additional corona shielding.

“Click here to view the recommended ClampStar Corona shield Installation procedure.”

There can be no generated RIV/TVI without corona and the only type of fair weather AC corona that is generally of concern is positive polarity plume corona which in air, at 25°C and sea level, appears (corona inception level) at a voltage gradient of approximately 30 kV rms/cm (76 kV rms/in).

Positive polarity plumes occur on the positive half cycle and are so named from the appearance of the corona discharges. Positive polarity plume corona is audible and generates significant RIV/TVI.

In laboratory RIV / corona tests two corona levels are usually obtained; corona inception on rising voltage and extinction as the applied voltage is reduced. Extinction generally occurs at a lower voltage than inception due to ionization of the surrounding air. There are two other types of AC corona that occur at lower voltage gradients. Brush at approximately 25 kV rms/cm (64 kV rms/in) and glow at 20 kV rms/cm (50 kV rms/in). Both are also named for their visual appearance and neither generates objectionable fair weather corona.

Under wet conditions virtually all energized electrodes are in corona, including the phase conductors. We have completed RIV tests on 230 kV assemblies with original prototype 230 kV corona shields that resulted in positive polarity corona extinction within 10 kV of nominal 345 kV phase to ground voltage. That shielding was made from 1.5” OD tubing and a Corona Test Report with that shielding on CSF-1108-036 is available. The 345 kV shield is made from 2” OD tubing and the shield for 500 kV is made from 3” OD tubing.

Yes. Full scale laboratory RIV/TVI tests and corona observations have been completed on CSF-1108-COR345 and CSF-1302-COR500 units at 345 and 500 kV, respectively. CSF-1108-COR345 is corona-free and generates no significant RIV/TVI above background at 240 kV RMS L-G (20% above nominal) and the same applies to CSF-1302-COR500 at 350 kV RMS L-G (20% above nominal). Since the same corona shields are provided with CSF-1108-COR230, that unit will be corona free at 230 kV and the results also apply to CSR-1108 units with rigid rails. “Click to request a copy of the CSF-1108 and CSF-1302 RIV Corona Test Report”

Yes, and ClampStar sizes are also available for applications on all distribution and transmission conductors through 765 kV, as well as OHSW and OPGW.

Connectors, Clamps, and ClampStar® – How are they different? A connector can be defined as a device for joining two or more conductors to provide a continuous electrical current path. Connectors generally fall into four types; automatic, compression, wedge, and bolted. The electrical and mechanical requirements for all are defined in ANSI C-119.4, “American National Standard for Electric Connectors – Connectors for Use between Aluminum-to-Aluminum and Aluminum-to-Copper Conductors Designed for Normal Operation at or Below 93°C and Copper-to-Copper Conductors Designed for Normal Operation at or Below 100°C”.

That Standard consists of four current classes:
Class AA (Extra Heavy Duty) – High current cycle test duration
Class A (Heavy Duty) – High current cycle test duration
Class B (Medium Duty) – Moderate current cycle test duration
Class C (Light Duty) – Low current cycle test duration
And four tension classes:
Class 1 – Full tension, 95% rated conductor strength
Class 1A – Normal tension, 60% rated conductor strength
Class 2 – Partial tension, 40% rated conductor strength
Class 3 – Minimum tension, 5% rated conductor strength
Current Class AA is intended for applications on aged conductor while Class A is for application on new conductor. Most automatic and compression connectors for transmission conductors will be rated Class A current and Class 1 tension. Some wedge connectors will be rated Class AA current and Class 1 tension. Bolted connectors will normally be rated Class A current and Class 1A tension for ACSR conductors, for example, because they cannot directly grip the steel core and any core gripping force must be transferred through the outer aluminum strands. In addition to ANSI C119.4, specifications for bolted clamps and connectors are also discussed in IEEE C135.100.

Clamps: Clamps are primarily intended to support conductors, as dead ends, jumpers, and suspension supports. Clamps are usually outside the electrical current path. IEEE C135.100 covers quadrant and straight-line bolted dead end and suspension clamp ultimate and slip strength requirements.

ClampStar®: ClampStar Connector Correctors are indeed different. They are engineered electrical and mechanical shunts that are primarily designed to reinforce and permanently restore the integrity of aged and degraded connectors, clamps, and damaged conductors thereby returning them to better than original condition.

Shunts, such as ClampStar are not presently covered by any American or International standards, but they are anticipated to be covered in a forthcoming Annex to ANSI C-119.4. Another ANSI C119.7 Subcommittee is working on a standard for “Connectors for Use Between Aluminum-to-Aluminum Connectors Operating Above 93°C”, and it is expected that shunts will be an Annex in that standard as well. That standard is aimed at HTLS (High-Temperature Low Sag) conductors that can operate at temperatures up to 250°C continuously. There are several questions about the connector test temperature for use on HTLS conductors by connector manufacturers. However, there is no question about ClampStar. Several ClampStar units have successfully completed 500 cycle current cycle tests at conductor temperatures of 390°C and all will do so. ClampStar units for larger conductors can also be tailored to meet Class 1 full tension requirements alone.

Although ClampStar is designed to be used in conjunction with a primary connector (or damaged conductor) that is holding line tension at the time it is normally installed, ClampStar is tested alone, without a primary connector, conductor, or other device in place. Under those conditions, all ClampStar units are designed and tested to hold a minimum of 60% of the rated breaking strength (RBS) of the largest and strongest conductor within its clamping range. Thus, they have a minimum tension rating of C119.4 Class 1A normal tension, which is a class, intended primarily for bolted connectors. That 60% rating can be compared to normal operating line tension ranging from approximately 15% – 30%.

ClampStar is installed mechanically in series and electrically in parallel with a hot splice or other compromised connector, conductor, clamp, or other device and by shunting the majority of the electrical current around that device, the device temperature will immediately return to near ambient. Further thermal degradation is prevented, and any slip that may have occurred prior to ClampStar is halted and further slip prevented by the mechanical reinforcement provided by ClampStar.

Because the mechanical tests are conducted without a primary connector in place, albeit one which is degraded, ClampStar holding strength alone is somewhat superfluous because it does not truly represent actual field applications. However, the combination of a primary connector and ClampStar will result in ANSI C119.4 Class AA current and Class 1 (95% minimum) tension.

“Click here for a downloadable, PDF version of this topic”

ClampStar® has little effect on the conductor’s self-damping characteristics due to its relatively small mass and, if anything, it will tend to diminish propensity to gallop because it is difficult to establish a wind foil on an irregular shape and the ClampStar® will tend to create turbulence (which also diminishes Aeolian vibration).

NOTE: Damper placement is never an exact science. Typically, utilities obtain placement recommendations from the damper manufacturer and those recommendations will vary, based on the damper characteristics. All are based on energy balance but, it is impossible to locate dampers such that they are on anti-nodes of vibration loops over the range of susceptible laminar wind velocities. It’s a very dynamic environment and damper placement becomes a matter of compromise. For example, the worst possible damper placement is on a vibration node and the reason for two dampers on one end of a deadend span is often to simply be sure that at least one will always be somewhere on the quarter cycle of a vibration loop.

Additionally, we have done some computer vibration analysis with hypothetical conductors, spans, tensions, etc. using a couple of different software packages and, if anyone would like an analysis of a specific case, we would welcome the opportunity to model and analyze it (and we do have the ability to simulate a defined mass anywhere in the span). Click here for more details.

The wind concerns appear to be ClampStar’s relatively low mass and wind profile effects on conductor mid-span blowout as opposed to Aeolian vibration. Aeolian vibration is the high frequency (3 – 150 Hz) low amplitude (0.01 – 1.0 times the conductor diameter) vibration that results from laminar wind flow over tensioned conductors at perpendicular wind velocities of 2 – 15 mph. Below 2 mph there is insufficient wind power to induce vibration, and above 15 mph, the winds tend to be too turbulent to remain laminar. The line environment and shielding by trees, buildings, or other structures are also important in determining the probability of exposure to laminar winds. Vibration tests on ClampStar rigid and flexible 1108 units on 795 kcmil 26/7 Drake ACSR have been conducted by Kinectrics North America in Toronto, Canada. In those tests both ClampStar units were found to not contribute to vibration and the resulting conductor strains were well below those that could cause strand damage on either the aluminum or steel core strands. In fact, ClampStars of both types reduce the reflected vibration traveling wave by attenuating the incident incoming wave.

The concerns about wind loading and galloping are probably best addressed by example. Let’s use the popular 795 kcmil 26/7 (Drake) ACSR, with an outside diameter of 1.108”, a rated breaking strength (RBS) of 31,500 lbf, and weight of 1.094 lbs/ft. The corresponding standard ClampStar for that conductor is CSR-1108-040 which weighs 27 lbs and has an overall length of 79”.

A service area that falls into the NESC light and medium loading districts will have the following loading criteria:

Light: 0” ice, 9 lbs/ft² horizontal wind pressure, and a constant added to the resultant of 0.05 lbs/ft of conductor length.

Medium: 0.25” ice, 4 lbs/ft² horizontal wind pressure, and a constant added to the resultant of 0.20 lbs/ft of conductor length.

For convenience, a span length of 500 ft and final tension of 25% RBS was chosen. This tension is likely greater than actual loading but it results in a conductor length that is only slightly more than the span length.

Galloping of a tensioned conductor requires specific conditions; steady winds similar to those that cause Aeolian vibration and ice, snow, or a conductor shape that forms a “wing shape” on the leeward side of the conductor. That wing provides the alternate lift and drag required to initiate conductor gallop. There are some regions of North America that are prone to gallop, such as the flat plains in the midwest, long river crossings, lakes and large bodies of water that freeze in winter, and similar regions. 

In terms of wind blowout, the most severe is the light loading district in which the blowout angle is 0.01° in this example with and without a ClampStar installed at mid-span. The ClampStar unit actually reduces wind swing slightly by increasing the conductor mass. The wind input energy is simply insufficient to overcome the conductor mass.

For the medium loading case, the calculated blowout angle is 0.006°.

Ice density of 57 lbs/ft³ is assumed for ice loading.

The short answer is “it depends”. For instance, if you are moving a line and must do the work energized you may be concerned with the weight of the ClampStar units. However, for the purpose of moving the line, ClampStar is a perfect tool that can be used and then removed and reused after the line is relocated.

Of course, factors such as; conductor/span length, sag, and splice location must all be considered. 3 ClampStars per span is commonly considered to be the max, but depending on location, perhaps only one or two if they are both in the middle of the span, but if they were all located close to the crossarms, as many as four could be installed and it actually raise the conductor slightly in the center, reducing the sag.  Presently, there is no hard rule or standard, every situation may be different.
Consider the following scenario:
Suppose you had a 300 foot distribution span of #2 ACSR conductor.  If you installed CSR-0325 ClampStars over the entire span, end to end, there would be 138 of them!  Now consider that ice weighs roughly 57.2 lbs/ft3 which is 0.033 lbs/in3.  ½” of radial ice on a #2 conductor will be roughly 1.1in3 per inch, and over the length of a CSR-0325, roughly 26 inches will be 29in3 x 0.033 lbs./in3 = 0.96  pounds.  This is 27% of the weight of a CSR-0325.
Now, If you figured 27% of those original 138 ClampStar units, it would be 37 ClampStar units. If they were equally spaced, they would be 6 feet apart. That would be the equivalent load on the line as ½” of radial ice, which is the ice loading requirement for Chicago, and not particularly unusual.
37 ClampStars in a 300 foot span! Now, would that create a lot of sag? You bet!  Some spans might break with the weight.  
The point is, even 6 or 7 ClampStar units would make no difference in the grand scheme of things mechanically. Now when you consider economics, I would think by the time you exceeded six units per span, you would be marginal, compared to the cost of replacing the span.
Of course some things just don’t make good sense.  As stated, each span has different characteristics, and trying to calculate all the scenarios possible would take decades – and at the end you would likely conclude that three per span would be the maximum number – but there may be instances where one might use a couple more.

Yes. ClampStars can be installed on Self Damping (SD) conductor? Click the following link for a detailed article on the subject: “ClampStar® and Self-Damping Conductor.”

The primary reason is the available system fault current diminishes with distance from the sources. In an attempt to quantify this, representative fault current calculations were made on a “typical” 34.5 kV circuit. I’ll call it “typical” because no circuit details or transformer nameplate data were available. We do know that the utility uses both 336.4 kcmil (Linnet) and 636 kcmil (Grosbeak) ACSR conductors on their 34.5 kV circuits and it is assumed that both are loaded to their 75°C maximum operating temperatures. The transformer used for these calculations was arbitrarily selected as 34.5 kV, 95.0 MVA, X/R=5.0, 5%Z (which may or may not be representative of the actual transformer). Click here for more details….

The ClampStar CSF & CSR-0883 is the correct part number for this application. Although CSF & CSR-1108 would also fit the 477 kcmil conductor, there would be no advantage in going to the larger size unless you also have additional applications for larger conductors that exceed the maximum diameter of CSF & CSR-0883. In that case, there might be some inventory advantages in using the CSF or CSR-1108 for both.

That number represents the length of the opening or window between the two clamping sections to fit over the splice or other connector. For instance part number CSF-0883-30 (indicates a 30” long window). That defines the required length of the flexible cable rails. That is the approximate length that would probably be required to fit over most splices.Example: The nominal uncompressed length of a Burndy splice YDS37RP1 is 26-3/8”, the installed length will be greater due to extrusion of both ends during crimping. The length increase due to extrusion will depend upon the installation tooling and number of crimps (which for YDS37RP1 will likely be either 4 or 12 crimps per end; depending on the die set). Click here for an explanation of the ClampStar part number key code.

All ClampStars are supplied by the factory with pre-installed torque limiting nuts, or set screws depending on part #, containing an outer section that is designed to snap off when the correct torque level is attained. The remaining nut or set screw can be removed in the event a need arises to do so.

When the ClampStar® (CSF, CRU & CSS) units are being installed with hot sticks you need something to grab onto to support the ClampStar flex connector. The Installation Kit contains an eyebolt with a flat washer welded to the eye near the threaded base. The threaded bolt part screws into a tapped hole in the body of the ClampStar and provides a secure means to which a clamp stick or “shotgun stick” can be readily attached. This is removed after installation to be used for the next CSF, CRU or CSS unit installation. This replaces the welded in-place hot stick loop on CSR ClampStar units.

It depends upon the planned work method and system voltage. ClampStar can be installed with the line de-energized and grounded, or energized by either bare hand or hot stick work methods. Whichever method is employed it must be conducted safely by trained and qualified workers and meet all applicable safety codes and regulations.

Required Equipment and Tools:

  • Clean stainless steel wire brush to clean the conductor over both clamping areas.
  • Deep well sockets or drivers, as required (depending on the unit being installed). Those with 3/8” torque nuts require a 9/16” socket, while those with ½” torque nuts require a ¾” socket. Some larger units are equipped with torque-limiting set screws which require a T-60 Torx®, 6-point “star” bit, or ¾” socket for installation.
  • Torque-limiting nuts and set screws assure proper installation torque with the outer portion shearing at 20 ft-lbs for 3/8” and either 40 or 55 ft-lbs for ½” and set screws.
  • Power drills (rattle guns) can be used to significantly reduce installation time.

If removal or relocation of an installed ClampStar is ever needed, a ¾” socket is required for 3/8”, 15/16” for ½”, and a T-45 Torx® or 6-point “star” bit for set screws.

CC² is a proprietary compound which we designed specifically for ClampStar, and consequently is suitable for any high-temperature applications. It has a proprietary polyalphaolefin base which is stable to temperatures of 250 degree C (482 degree F) and contains variations of very fine aluminum-nickel grit which enhances the electrical conductivity (typically by a factor of about 25% compared to other inhibitors) as well as zinc dust for thermal conductance. A similar inhibitor formulation [using the same synthetic base] has been tested successfully through 4,000 hours of salt fog testing. Therefore, we have no concerns with intended applications and, indeed, it mirrors several other Coastal Utility environments with which we are working.

CC² is designed for extreme high temperatures. All ClampStar units are designed for continuous use on ACSS conductor, which is rated for continuous operation at 250C (482F) conductor temperature. In addition, normal ClampStar installations are made on aged, weathered conductor. To qualify to our standards, our testing includes equivalent thermal stress to the same level as ANSI C119.4 Class AA used to qualify connectors for use on aged, weathered ACSR (rated for continuous operation at 75C) with a test parameter of 175C rise over ambient, resulting in a conductor test temperature of approximately 200-205C (392-401F). To achieve that same stress level for a 250C, we designed ClampStar units to be tested at 390C (734F).

Approximately 1/64 of an inch of CC² is applied under the keepers, and upwards of 1/16 of an inch in the conductor receiving groove. Essentially, CC² is applied to all surfaces which are in contact with the conductor, and serves to protect the electrical interface asperity contacts from ingress of oxygen and electrolytes, assuring longevity of the connection and protecting it from corrosion.

“Inhibitor washout” is generally not washout at all. It’s more like “inhibitor runout” and it certainly can be an issue for compression connectors.
There are many different joint compounds, inhibitors and sealants made from natural and synthetic oil bases. Depending upon the intended application, they may or may not contain grits of various materials, shapes and sizes. As with all compounds, the base oil imparts specific characteristics but the final properties are dependent upon the compounding constituents.

One means of evaluating the susceptibility of inhibitor washout or runout is the inhibitor’s dropping point. Dropping point is the temperature at which the inhibitor becomes fluid enough to drip. It indicates the upper temperature limit at which the inhibitor retains its structure. It does not necessarily indicate the maximum service temperature. There are well-known inhibitors that have dropping points of 50ºC that are commonly recommended for use up to maximum temperatures of 93ºC, depending solely on the film that remains to seal the joint.

Inhibitor washout or runout typically occurs when the joint temperature exceeds the inhibitor dropping point and the base oil begins to run out.

In ClampStar, inhibitor washout and runout of our proprietary CC² Compound is of no concern. It’s designed to withstand the maximum conductor operating temperatures that are being considered. It is non-melting with a dropping point in excess of 260ºC.

Yes, provided the unit is appropriate for the new location. ClampStar® units are installed with two-part torque-limiting nuts or set screws to ensure proper installation torque without the need for torque wrenches or other devices. The CSR-0325-015 unit has 3/8” keeper bolts. All other units use ½” keeper bolts or set screws. The torque nuts of CSR-0325-015 units are tightened using a 9/16” deep well socket and the outer 9/16” nut shears at 20 – 25 ft-lbs leaving a ¾” nut in place. The torque nuts of larger units are tightened with a ½” deep well socket and the outer nut shears at either 40 or 55 ft-lbs, depending upon the unit, leaving a 15/16” nut in place. The largest units are equipped with torque-limiting set screws that are tightened with a T-60 Torx®, 6-point “star” bit, or ¾” socket and the outer head shears at 55 ft-lbs.

All units can be removed from service by removing the keeper nuts with either a ¾” or 15/16” deep well socket, or T-45 Torx® or 6-point “star” bit (set screws can only be loosened with those bits). Retain the flat and spring washers for reuse and visually inspect the unit for any damage. If any damage is evident, do not reuse and contact CC USA. Although the unit can be installed in a new location using the removed nuts, it is recommended that new torque nuts be used to ensure proper installation torque. Reinstallation also requires recoating the conductor grooves with CC² compound. This proprietary compound and replacement torque nuts are available from CC USA. Although it is possible to remove, inspect, and reinstall most units in the field, it is recommended that they be returned to the factory for inspection and reconditioning. Return to the factory is required for units with set screws.