Modernization of electric drive systems for hoisting cranes

The practice shows that the mechanical resource of main structures for electric hoisting cranes is twice as much as the resource of their electrical part, particularly, of the control systems. In the process of the crane operation the electric drive requirements can change due to modification of the technology or reconstruction of the existing production. Replacement of hoisting cranes by new ones requires big capital investments connected with disassembling and assembling operations.
So, the actual task is economically and technically sound reconstruction or modernization of the crane drive control system.
The Dvesta enterprise renders the full complex of services on modernization of the relay-contactor control systems of electric drives for hoisting cranes to noncontact thyristor ones or those with the use of the frequency converters. 
The choice of a type of the noncontact control system is performed on the basis of the technical and economic assessment with direct participation of the customer.

Replacement of the relay-contactor control system by the thyristor one

For obtaining the full analog of the relay-contactor drive the thyristor system of the crane drive (TEDF type) is selected. The advantages of such modernization:

• crane parameters are not changed;
• asynchronous engines with a phase-wound rotor can be used;
• values of the thyristor and relay-contactor systems of the crane drive are comparable;
• circuits of the thyristor systems of the crane drive are made in a way usual to the service personnel;
• modernization of the electrical equipment for a bridge crane is performed with the least costs for the customer.

Besides the updated crane control system, such modernization allows the company to obtain the following advantages of the thyristor control system of the crane drive as compared with the relay-contactor one:

• high probability of trouble-free operation and operational reliability of the electric crane equipment; 
• exclusion of the mechanical contacts in the power circuits of the thyristor drive for the engine with a phase-wound rotor;
• high performance of the TEDF system and possibility of the increased frequency of the drive switches-on.  

These advantages are especially urgent for the heavy-duty cranes during intensive operation in the environments with the increased dust and moisture content, for example, in the cement production, mining industry, metallurgy, and in ports.

Replacement of the relay-contactor control system by the variable-frequency one.

For obtaining the advantages of the variable-frequency drive during modernization of the crane control system, the system of TEDF-KM type with the use of the frequency converters and kitting of the Siemens Company is offered. 
The variable-frequency drive has the following advantages as compared with the relay-contactor system:

• accuracy of the cargo positioning due to the high quality of speed regulation is improved;   
• service life of the mechanical crane elements is increased;
• crane control comfort is improved;
• asynchronous engines with the short-circuited rotor are cheaper and more reliable than engines with a phase-wound rotor.

The use of the Siemens equipment offers the following advantages:

• high reliability of the control system is stipulated by high reliability of the component parts;
• considerable energy saving due to the use of the opportunity of the new type of the Sinamics frequency converters to return the braking energy into the (recuperation) network;
• flexible and operative change of the crane operation algorithms without altering the electric part due to the application of the industrial programmable controllers SIMATIC S7, which allows to adjust the control system “on site” taking into account individual customer’s requirements;
• ease of the control system adjustment and visualization of the incipient failures on the control panels that are parts of the system;
• ease of the incorporation of the additional options into the control system, such as weight measurement, cargo anti-bouncing, crane anti-collision system, bridge aligning relative to craneways, and others. 

The crane drive system, TEDF type (thyristor or with the use of the frequency converters), can be made:

• as a control panel with the protection degree IP00,
• as a control cabinet with the protection degree no less than IP43,
• at the electric room with the protection degree no less than IP54.

Additionally the Dvesta enterprise can manufacture a control console, entrance bays, terminal and connecting boxes.

The process for modernization of the bridge crane control system comes to the following stages: 

1. Crane survey work, repair list work.
2. Calculation-and-estimate documents work.
3. Signing of an agreement for the equipment delivery, signing of agreements on design, wiring, starting-up and adjustment works, technical task with a separating sheet.
4. Production project development.
5. Material, devices and apparatus kitting.
6. Production of the complete devices for electric drive control.
7. Preliminary equipment testing.
8. Delivery of the equipment and materials to the site.
9. Execution of repairing, disassembling and assembling operations.
10. Execution of starting-up and adjustment works.
11. Commissioning.
12. Warranty service is 12 months.
13. After-sales service.