Crane and crane components supplier Demag, a brand of materials handling solutions provider Terex Materials Handling & Port Solutions, launched a new range of Dedrive Pro 880 inverters in August that offers a number of benefits for crane control.

One of the central features of these new inverters is direct torque control, which makes it possible to directly control the speed and torque of the crane without having to track speed and position by means of sensors and encoders for travel applications. As a result, the inverters offer highly dynamic vector control of long-travel, cross-travel and hoist drives, thus reducing the amount of sensitive sensor technology required on the crane.

The inverters are equipped with Demag CraneControl, a complete application program for crane drives. All the functions that a crane manufacturer needs to equip a unit with are, thus on board, including brake control with brake feedback evaluation, torque memory and a system check. It is also possible to select field weakening operation with partial load and synchronous control for operating several hoist units.

Saved as complete software solutions in the application program of the Dedrive Pro 880 inverters, these functions considerably reduce the costs and work of engineering for a crane manufacturer, and make many practical and innovative control functions available to the crane operator, says Demag.

The Dedrive Pro 880 also features model-based load sway reduction, a crane-specific function of the inverter. This model-based function effectively reduces the load sway, based on a mathematical model, rather than data supplied through ssensors, allowing for considerably higher handling rates and safer crane operation.

The application program, moreover, includes crane-specific service functions, such as an elapsed operating time counter for the crane, a load spectrum for the hoist unit and a starting frequency for the brake. Remote diagnosis enables the crane control system to be viewed from anywhere, while its ability to generate error messages can help prevent damage to the unit and, therefore, reduce maintenance downtime.

The new Dedrive Pro 880 frequency inverters are available as a complete series in the Demag drive systems product range for crane drives with 0.55 kW to 560 kW power ratings. Nine wall-mounted units with varying frame sizes (R1 to R9) and two free-standing models (R10 and R11) complete the range.

Convenient operation is not only guaranteed during the configuration phase, but also in the daily operation, with a removable control panel equipped with an intuitive menu serving as the interface between the operator and the machine. The inverters are also ideally suited to crane operation in rough conditions and start-stop operations.

Additional Functions
In addition to the standard safe ‘torque off’ function, the optional safety function module of the Dedrive Pro 880 inverter supports further standard compliant functions such as safe stop, safe brake control, safe limited speed and safe maximum speed.

Dedrive Pro 880 inverters in master/slave mode can also implement synchronous control of up to four hoist units, enabling precise handling, even of highly sensitive loads. This function is also included in the application program of the inverter as is the master/follower operation with torque tracker in drive-to-drive mode. The torque tracker ensures that torque is shared between two mechanically connected geared motors.

The Dedrive Pro 880 is network-enabled and features digital and analogue input/output extensions and interfaces for signal evaluation of different pulse generators. It can also be equipped with communication modules for various standards.

he inverter module is fitted with an integrated Web server to enable users to gain remote access to the inverter data. The user can access the website of this module using a 3G modem or with a standard computer, tablet or smartphone. The module can record process and drive data, which are saved internally or transferred to a database. The remote diagnosis module also issues warning and fault messages, thus allowing for timely preventive maintenance measures to ensure higher crane availability.

As a result of the many crane-specific configuration options in the application program, crane design engineers can dispense largely with costly programming and still implement sophisticated functions tailored exactly to the requirements of materials handling and crane operation.

Terex operates sales and service networks in more than 60 countries, including a branch in Johannesburg. The company provides solutions for various applications, including quarrying, mining, refining, transportation, shipping, construction and manufacturing.