Overload Protection Case Study
Overload protection device for monitoring crane load in the steel industry
PIAB Sweden AB submitted a proposal for an overload protection system for DEMATIC. The client needed to monitor load in a crane and have the ability for automatic shutdown in the event of slack rope or overload. The end user of this overload protection capability (HKM) also had specific requirements from its maintenance department for recording the hoist operation according to FEM 9755-3, FEM 9511, ISO 12482-1. These cranes have an "anti sway" system and an 8x2 reeving configuration with eight dead ends.
Customer: DEMATIC, Wetter, Germany.
End-user: Hüttenwerke Krupp Mannesmann AG (HKM), Germany.
Overload Protection Solution: Eight PIAB LKVE 8 Electronic Force Transmitters were connected directly to the eight wire rope dead ends. The output signal from the PIAB LKVE (4-20 mA) was wired into the PIAB CSM Crane Safety Monitor 8:517. The PIAB CSM has the ability to evaluate and compute the signals and offers various alarm level settings, and also displays the actual load and records the operation in each hoist.
The PIAB overload protection solution was selected for the project due to the following features and benefits:
• Simple and fast installation, which can be achieved without affecting the design or the working range and capacity of the overhead travelling cranes.
• Factory calibration further facilitates installation with preset switch values.
• The powerful output signal resists interference as the PIAB LKVE transducers, when connected to the wire rope dead ends, provide a 4 - 20mA output signal. This can be installed easily, in combination with other electrical cables without disruption.
• Easy adjustments as all limit settings, time delays, and other settings, are easily adjusted on site with the 6 push buttons on the panel of the PIAB CSM electronic unit. Screwdrivers and voltmeters are not required for these adjustments.
• Imbalances are monitored in the hoisting structure, allowing uneven loading in each wire rope reever to be determined on the PIAB CSM unit’s display. This display is also key for wire rope replacement or adjustment.
• Hoist operational cycles and information on conditions is recorded from the PIAB CSM to allow a proactive maintenance schedule.
• The PIAB CSM has a failsafe capability that provides an overload indication for faults as they happen.
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