Functional Overview

 

Functional Overview

Functional Description

The Overload_EN15011 function block is applicable to the following types of cranes:

o Industry Cranes (hoisting movement)

oConstruction Cranes

 

The function reads the torque inputs from the hoist drive. It detects an overload situation according to the calibrated torque threshold and gives an alarm indication by lights and horn as well as stopping the upwards movement of the hoist. Additionally an alert indication by lights and horn at 90% of the nominal calibrated load is generated.

The function also shows the actual mass of the load with an accuracy of +/- 5%, depending on the setting of the speed loop of the drive.

The FB is conforms with the requirements of EN15011. Furthermore, it is possible to connect a load cell instead of the drive torque value.

An internal calibration procedure allows easy commissioning of the thresholds and the weight output.

Why Use the Overload_EN15011 Function Block?

The intention of the function is to prevent running the hoist outside of its load capabilities by locking the upwards movement and protecting the mechanical structure of the crane, prolonging its life and reducing maintenance. The actual weight output of the function can be used to calculate lifetime applied load and to adjust the maintenance cycles according to the real use of the crane. The alert output at 90% of the nominal load can be used to operate the hoist at lower speeds to reduce stress to mechanical components, such as the gearbox. The function includes an algorithm to detect a fast and steep rise in torque of the drive to handle sudden changes of the load, i.e. when the lifting accessories, like chains or ropes attached to the hook, are tensioning.

The function includes an algorithm to detect a fast and steep rise in torque of the drive to handle sudden changes of the load, for example, when taking up the slack of the lifting accessories such as chains and ropes before reaching the tension of the bearing of the load on those accessories. This algorithm therefore would make a second measurement to replace the non-load values that were first measured.

This function block is intended to have significant influence on the physical movement of the crane and its load. The application of this function block requires accurate and correct input parameters in order to make its movement calculations valid and to avoid hazardous situations. If invalid or otherwise incorrect input information is provided by the application, the results may be undesirable.