Automatic switch-off system prevents chain damage on cranes

The video above explains the EC.PR system (E-chain Push/Pull Resolver) in 60 seconds.

Energy chains for protecting moving cable assemblies in cranes can be damaged by foreign objects like loose tools, causing costly system failures. This prompted igus to develop a new push/pull force monitoring system. The EC.PR system records the precise force values of the moving end and adjusts the force limits, preventing potentially catastrophic damage to the crane and expensive repairs.

A system failure is the worst-case scenario for crane operators. Heavy costs are incurred for repair, downtime and loss of production. igus has developed the EC.PR system – or E-chain Push/Pull Resolver – especially for long travel energy chains from 150 metres and longer, which uses sensors to determine the push/pull force of the energy chain and automatically switches the chain off when a defined force is exceeded, preventing expensive damage to the chain.

Changed value detected

If a foreign object enters the energy chain, or if the guide trough that houses the chain flexes, the push/pull force increases at that position, and the EC.PR system detects the changed value and switches off the energy chain. The system receives the positional information from additional modules of the Siemens PLC, an OPC-UA server, and analogue or digital position measuring systems.

The EC.PR system can be easily integrated into existing controls and switch cabinets, advises igus.

Tested under real outdoor conditions

The EC.PR system consists of two sensors that communicate with each other. One sensor measures the push/pull force of the e-chain, while a digital distance measuring system determines the exact position of the trolley or the moving end of the e-chain.

The measuring system uses what igus calls "beacons" that are attached to the outside of the guide trough at a distance of 500mm apart. Each position, and thus each beacon, is assigned a specific push/pull force.

If the assigned maximum push/pull force of a position is exceeded, the system switches off automatically via the EC.PR. The user can remove the foreign object from the energy chain, reset the system and put the e-chain back into operation.

The new system has already been successfully tested at the 200m long outdoor test rig at igus in Cologne, Germany.