The grab crane for end user E.P. Stevedoring is a Lemniscate crane, which was placed on a self floating pontoon.
To drive the various motions we applied standard squirrel cage motors. The advantage of these motors is that they imply low maintenance and a long life. The motors are driven by frequency controllers that are powered by a common DC-Bus in combination with two rectifiers. In addition to this, brake choppers, with corresponding break resistors, were used. As a result this configuration reduced the number of electrical components.
All communication between the crane controls, the frequency controllers in the E-room and the cabin, operates through Profibus-DP. The communication between the crane controls and the equipment on and around the pontoon also goes through a separate Profibus-DP network. The great advantage of this system is that it implies a significant reduction in the number of cables. It also means that the control system is made flexible, as it is simple to apply software modifications in functionality.
Alongside the usual operating controls a Touch Panel was placed in the crane cabin. As a result, the crane operator always has the correct data, relevant at the time, and in case of failure, detailed information can be displayed.
Project: 25 ton crane pontoon, Egypt Client: Figee Crane Building B.V., Amsterdam
Okay Electric Engineering delivered the electrical installation and crane controls of this floating pontoon. The end user “Suez Canal Authorities” will use this crane on the Suez Canal. After previous delivery Okay Industrial Systems has been asked to deliver two more identical crane pontoons for SCA.
The electric installation meets the clients’ specifications and the standards set up by Germanischer Lloyd.
The crane is a type jib, in which standard squirrel cage motors have been chosen as drives for propulsion and the various motions. The motors are driven by frequency controllers, which are powered by a common DC-Bus, in combination with a rectifier. In addition, break choppers, with corresponding brake resistors, are used.
The grab crane is a type Lemniscate, which was placed on a floating pontoon.
Standard squirrel cage motors were chosen to drive the various motions. The movement of the top of the crane is hydraulically driven. The motors for hoisting, closing and pivoting motions are driven by frequency controllers that are powered by a common DC-Bus in combination with a rectifier.
All data communication between the PLA, the frequency controllers in the E-room and the alarm display in the cabin, operates through Profibus-DP.
Project: Two 50 ton portal grab cranes, Austria Client: Figee Crane Building B.V., Amsterdam
The portal grab cranes are located in the harbour of Voest Alpine in Linz and are used for the transhipment and unloading of iron ore ships. The cranes have a very high capacity which is partly obtained because the various motions are executed in a fast and efficient way.
At high speeds it is important for the crane operator to keep the crane under control. To ensure this, the controls were equipped with a fully automatic “Anti Sway System”. This system hooks onto the trolley travel motion and ensures that the grab does not sway uncontrollably.
Furthermore we equipped the trolley drive with a “traction control system”. The torque is regulated and therefore ensures that the drive wheels do not slip in case of heavy snowfall or frost. The crane operator can also choose to use the semi-automatic mode, in which it is possible to enter coordinates by using the touch panel, which causes the grab to automatically follow the contours of the heap of iron ore.
As the cranes have a high overvoltage, all the Profibus-DP, video and intercom connections reach the trolley through fibreglass, which ensures a failure insensitive transmission. There is also a fibreglass connection between the mainland and the crane. Through this interface one can communicate i.e. with the automatic product discharge system and data logging system.
The product discharge system consists of an unloading bunker on the crane construction with various conveyor belts behind it. There are a weighing system and an automatic speed system on the belt, which ensure a constant product flow, regardless of the cranes’ travelling speed.
The data logger system registers the ageing of the bearings in the hoist motor and the gearbox, by means of vibration sensors.
In addition we equipped the cranes with laser controlled collision protection, automatic misalignment correction, an extensive intercom system, a professional video installation and a sophisticated lighting system which ensures good sight, even during foggy weather.
We replaced the electrical installation for the hoist and close motions of the 16 ton floating grab crane the “Reiger”. The previous electrical drive installation of the hoist and close motions was replaced by a frequency controlled drive installation, for which the original slip ring induction motors were re-used.
The advantages of this frequency controlled drive installation, as opposed to the previous drive installation, are:
- Increased efficiency, which reduces fuel consumption.
- Optimization of the grab company by delivering modern grab logics.
- Improved and manageable control system will result in higher transhipment capacity.
- Increased reliability by using modern technology. There is less chance of failure and downtime is minimized.
Project: 15 ton floating grab crane ‘EP-ship I’ Client: E.P. Stevedoring, Rotterdam
The grab crane was placed on a self-propelled pontoon. We chose standard squirrel cage motors do drive the various motions. The motors for hoisting, closing and pivoting motions are driven by inverters that are powered by a common DC-Bus in combination with a rectifier.
All data communication between the PLC, the controllers in the E-room, the alarm display and the controllers in the cabin, operates through Profibus-DP.