The
new generation of control and monitoring system, developed by Amtech
Electronics (India) Ltd, integrates the operation of EOT crane with
four rope grabe by using variable frequency drive, Crane controller
for controlling and monitoring.
Grabing
crane used to handle the powder material, having four rope which
operates hoisting and grabing operation.Synchronization of this
operation was carried out by differential gearbox. Being mechanical
synchronization, it prones to backlash and takes lot of time to
re-synchronize. Amtech has developed and successfully installed
automation system for the grabbing crane. Automation system control
the synchronization and whole crane operation like Cross Travel, Long
Travel, Hoisting, Grabbing and safety interlocks. Automation system
is using properly sized variable frequency drive for existing slip
ring motor or new induction motor to control the all operation. PLC
system take cares of Speed control, Thruster control, Synchronization
and Various interlocks.
Grab
crane is a type of crane used in Cement, Metal industry, Ports etc.
for handling of material in powder form. The grab mechanism is just
like two jaws hinged at mid-point, used to grab the material. This
mechanism can be operated by either hydraulic or electrical system.
In Hydraulic system the grab jaws are operated by hydraulic
cylinders. In case of electrical system, there are two rope &
drum assemblies on the crab trolley. The grab operation gets carried
out by one of the rope & drum assembly used to hoist the grab
which in turn, gets driven by electrical motor. The motors get
controlled by drive to allow multiple speed operations.
Frequent
Problems in grabbing cranes are:
- The original system in grab control uses a differential limit switch to get open/close positions & these positions cannot be changed. As this system is purely mechanical, setting the position is a tedious process The position of the switch can get disturbed over multiple operations & to be re-set again.
- Power & Rotor resistance contactors often required to change due to frequent operations.
- Slip-ring, carbon brushes maintenance.
- Arching, bigger size and bulkiness of motor puts extra load on trolley and bridge.
- Frequent problems in slip ring motors due to single phasing.
- Burning of resister box.
- Regular maintenance of current carrying contacts of contactor due to frequent braking and reversal involved.
- Motor & Gear box coupling bolts damages & respectively motor & gearbox damage due to jerky operations.
- Hoist & Grab wire rope broken out due to uneven load sharing.
- Poor life of brake shoe as brakes was used for braking the speed.
Features
- Retrofitting the crane using existing slipring motor/new induction motor and removed the mechanical differential gearbox limit switch operation.
- Close loop control with encoder feedback from rope drum, to synchronize the Hoisting and Grabbing operations with proper load sharing.
- For the crane operator, the crane works as if there were only a single hoisting device with the additional functions of “open” and “close”.Setting the nominal grab positions only has to be performed once after a change of a rope or grab unit.
- Latest series Variable frequency drive with state-of-the-art engineered panel with protection of crane vibration and dusty environment, ensures trouble free operation of the crane.
- Operator cabin is equipped with monitoring system, which gives status of whole crane operation to make the ease of operation for operator.
- User friendly HMI provides powerful diagnostic in case of any problem to reduce the downtime.
- Variable frequency drive control eliminates the problems of slip-ring motor contactor, resister and thruster brake.
Benefits
- Assistance from concept to commissioning.
- New system with existing components.
- Minimized maintenance reduces the cost and provides more up time.
- Ease of setting Open/Close limits through HMI instead of adjustment of mechanical limit switch.
- Optimized four-rope grab control minimizes cycle time and reduces stress on ropes.
- Higher reliability - Less Mechanical wear / tear – more uptime.
- Full motor protection.
- Smooth crane operation.
- Electronic braking hence reduced maintenance of brake.
- Energy saving.
- Easy troubleshooting.
- Quick and safe commissioning.
- Qualified after-sales service.
Visit
us:- http://www.amtechelectronics.com
