Final sections being lifted in by helicopter on 69m mast.
Helicopter lift of 2nd guy section for 69m mast.
Final mast section being lifted by erection mechanism on 39m mast.
INSTALLATION METHODS
The Trust Tower masts are not designed to be installed by the tilt-up method. The methods of erection are by helicopter, Tenergy's patented erection mechanism and by crane. All of these methods work at reasonably high wind speeds, have much lower construction risk than the tilt-up method, result in a more efficient and robust mast design and are intended to utilise available resources to the maximum.
HELICOPTER
For the Standard and Coastal mast designs the maximum weight of a base section will be approximately 150kg. Any of our masts can be assembled with a helicopter with this lift capability. Typically we lift 3 sections at a time and therefore look to use a helicopter with lift capability of 450kg.
We also recommend the lift rope to have an electric release machanism at the connection to the load. This prevents the lift strop falling onto the mast and prevents damage to any instruments.
ERECTION MECHANISM
The Tenergy patented erection mechanism can lift all the mast sections required for the full range of Trust Tower masts. The New Zealand patent will be issued in May 2009 and thereafter the next version of the mechanism will be developed.
The mechanism is expected to install any of the masts in one day, given suitable weather. This will reduce installation costs compared to helicopter installs.
CRANE
If suitable cranage is on site or close by then this can be a very cost effective installation method. Considering the top weight of some of the masts , for say 6m length being around 120kg, then very low capacity cranes with a suitable jib could be used. In fact any high reach lifting vehicle with nominal lift capacity could be used.
CABLE TENSIONING DEVICE
Tenergy's purpose built cable tension checking device can check the tension in any guy in seconds. The device significantly reduces installation times of the masts. Assuming pre assembly is completed beforehand of the 6m and 9m guy-to-guy sections then all the Trust Tower masts can be installed in typically 5 to 10 hours, assuming reasonable weather.
The guy tension checking device at work on the NZWF 51m Mast (permanent installation) at the Tararua site.
TENSIONING OF KEVLAR CABLES
For the kevlar guyed systems the pretension at installation time is set higher than the required tension. The kevlar cables then relax over the next 2 to 3 days to the desired tension. Thereafter the cables will maintain their tension with very minor variation, since kevlar has extremely low creep values and virtually zero coefficient of expansion.
ANCHOR STYLES
Trust Tower masts from 2009 will now be supplied with a specially designed anchor block and adjustment device. This eliminates the need for turnbuckle and simplifies the installation.
In addition this anchor block can be built into a pile or mass concrete foundation.
Special anchors may be needed for very sandy or rocky locations. Our civil engineers will assist with whatever conditions prevail ay your site.