FIELD OF THE INVENTION
The present invention relates to a wagon tippler having an improved control system for continuous wagon tippling operation with accurate zero positioning of the wagon tippling platform and sensorless counting of tippled wagons. More particularly, the present invention is directed to a PLC & VFD based digital control system with a operator control desk for rotary wagon tippler with VFD grade squirrel cage induction motor mounted with incremental encoder for speed feedback. Importantly, the control system favours accurate zero positioning of the wagon tippling platform (within ±5 degree) implemented in continuous tippling operation with braking almost at 5% of nominal speed, involving current sharing between the drives. A MASTER-SLAVE configuration for speed and direct torque control with Warm redundant scheme is implemented to change over the drive to any configuration. Advantageously, the control system involves a display and annunciation unit adapted to show the number of wagons tippled along with the speed and current taken by the motors. The control system according to the invention is thus capable of beneficial application in material handling plant of any steel, power or other industries involving continuous wagon- tippling operation with improved efficiency and higher productivity.
FIELD OF THE INVENTION
It is well known that Raw material handling plant (RMHP) is one of the most important units of any integrated steel plant. The operation in RMHP involves unloading of raw materials like iron ore, coal, limestone, dolomite etc. from railway wagon, weighing approx. 68T/wagon which is likely to increase in near future, with the help of Tram Car Pusher (TCP) and wagon tipplers (04 nos.) and finally conveying it to the stacker and reclaimer zone. Due to decrease in free time and increase in demurrage charges by Railways, the role of tippling has become more important to unload the railway wagons within specified time by minimizing the delays. Each tippler is having capacity to tipple 20 wagons/Hour.
The tipplers being crucial equipment were conventionally operated with slip-ring induction motors and the rotor resistance control for speed control leading to jerks/stresses in the associated electrical & mechanical equipment during speed changeovers. This resulted in frequent mechanical/electrical delays/breakdowns and

requires frequent attention to resistance boxes, electrical contactors & physical position of tippler. Apart from this there was no provision to count and display the number of wagons tippled. The wagons are usually spread over a distance of over a few hundreds of yards in siding after tippling which make the physical verification of empty rakes more trouble some and time consuming exercise.
There has been thus a need in the art to developing a wagon tippler with a system for continuous wagon tippling operation with accurate zero positioning of tippling platform without jerk, or frequent breakdown and maintenance causing delay, and also provide means for counting of tippled wagons and display it favoring easy and timely collection of empty wagons. The wagon tippling plant would be capable of tippling more number of wagons per day with less manpower thus making the operation cost effective and with scope of application of such systems in steel, power and other plants.
OBJECTS OF THE INVENTION
The basic object of the present invention is thus directed to a wagon tippler comprising warm redundant tippling control system for continuous wagon tippling operation without jerk with accurate zero positioning of the wagon tippling platform and sensorless counting of wagons.
A further object of the present invention is directed to a wagon tippler comprising warm redundant tippling control system for continuous wagon tippling operation with accurate zero positioning of the tippling platform (within ±5 degree) with braking almost at 5% of nominal speed.
A still further object of the present invention is directed to a wagon tippler comprising warm redundant tippling control system for continuous wagon tippling operation adapted to show the number of wagons tippled along with the speed and current taken by the motors through a display and annunciation unit, without needing physical counting of empty wagons spread over long distance.
A still further object of the present invention is directed to a wagon tippler comprising warm redundant tippling control system for continuous wagon tippling operation

comprising of VFD grade squirrel cage induction motor mounted with incremental encoder for speed feedback.
A still further object of the present invention is directed to a wagon tippler comprising warm redundant tippling control system for continuous wagon tippling operation wherein suitable VFD grade industrial squirrel cage induction motors are used replacing the existing slip ring motors to ensure jerk free operation, achieved by modification of half coupling on the motor side only of the motor-gear system.
A still further object of the present invention is directed to a wagon tippler comprising warm redundant tippling control system for continuous wagon tippling operation wherein MASTER-SLAVE configuration for speed and direct torque control with warm redundant scheme is used to change over the drives to any configuration.
A still further object of the present invention is directed to a wagon tippler comprising warm redundant tippling control system for continuous wagon tippling operation wherein the system ensures easy maintenance and trouble free operation with low investment.
A still further object of the present invention is directed to a wagon tippler comprising warm redundant tippling control system for continuous wagon tippling operation wherein the system favours reduced delay in tippling operation avoiding wagon derailment and need for platform adjustment thereby increasing the number of wagons tippled.
A still further object of the present invention is directed to a wagon tippler comprising warm redundant tippling control system for continuous wagon tippling operation wherein the system eliminates the physical counting of wagons tippled over long distance, resulting in saving of time of advice for collection of empty wagons due to display system for counting number of tippled wagons, and thus saving incidence of demurrage.
SUMMARY OF THE INVENTION
The basic aspect of the present invention is thus directed to a wagon tippler comprising warm redundant tippling control system involving warm redundant Master-Slave configuration for speed and direct torque control with scheme to change over the drive to

any configuration adapted for continuous tippling operation with accurate zero positioning of the wagon tippling platform (within ± 5 degrees) and dynamic braking resistance (DBR) for each phase.
A further aspect of the present invention is directed to said wagon tippler comprising two numbers VFD grade motors with higher frame size and shaft diameter having motor-gear Half-Coupling on motor side adapted to only match the same on gear side for introduction of cylindrical motor shaft;
VFD (Variable frequency drive) system comprising of position measurement sensors involving multi-turn absolute encoder, incremental encoders for speed feedback;
PLC and VFD with display & annunciator at operator desk and cable extension to control panels for interfacing with multi-point combined cam limit switch (for back up of absolute encoder) coupled with motor-gear system of the tipplerjand
a VFD drive located between other two drives feeding the two VFD motors, which acts as stand-by and can replace any other drive through a changeover scheme.
Advantageously, said wagon tippler comprising Synchronous Serial Interface (SSI) based multi-turn absolute encoder as position measurement sensor.
A still further aspect of the present invention is directed to said wagon tippler , wherein encoder based reverse rolling protection scheme/logic comprises dynamic braking and DC bus regulation.
Importantly also in said wagon tippler, said system is adapted to ensure braking almost at 5% of nominal speed with current sharing between the drives.
A still further aspect of the present invention is directed to said wagon tippler which comprises a display and annunciation unit for sensor-less counting of wagons tippled and its BCD display.

Other objects and advantages of the present invention are described in greater details with reference to the following accompanying non-limiting illustrative drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1: is the photographic image showing the pictorial view of the wagon tippler with the system for continuous tippling operation according to the invention.
Figure 2: is the schematic illustration of the wagon tippler arrangement of drive motors, shaft, gear/pinion and the tippling platform/cradle with wagon.
Figure 3: is the schematic view (system configuration) of VFD based Wagon Tippler Control System according to the present invention.
Figure 4: is the screen shot showing the typical process trend of current sharing/ DC Bus regulation of VFD based squirrel cage drive motors according to the system of the present invention.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING FIGURES
The present invention is directed to a system for continuous operation of a wagon tippler having an improved warm redundant tippling control system without jerk , with accurate zero positioning of the tippling platform and having means for sensorless counting and display of the number of tippled wagons. Accompanying Figure 1 is the photo image showing the pictorial view of the wagon tippler with installed system according to the present invention. Accompanying Figure 2 shows the schematic view of the wagon tippler illustrating the arrangement of the different components of said wagon tippler.
Accompanying Figure 3 shows the schematic view (system configuration) of VFD Based Wagon Tippler Control System according to the present invention. The system for continuous wagon tippling operation comprise the VFD (Variable frequency drive) system consisting of position measurement sensors i.e. synchronous Serial Interface (SSI) based multi-turn absolute encoder as position measurement sensor, incremental encoders for speed feedback, PLC & VFD with display and annunciator at operator desk and cable

extension to control panels for interfacing with multi-point combined cam limit switch (for back up of absolute encoder) coupled with motor-gear system of the tippler. The slip ring motors were replaced by suitable VFD grade industrial squirrel cage induction motors.
There is a VFD drive located between the other two drives feeding the two VFD motors, which acts as stand-by and can replace any other drive through a changeover scheme. This is a MASTER-SLAVE configuration for speed and direct torque control with Warm redundant scheme to change over the drive to any configuration. The dynamic conditions are controlled by designing/sizing suitable dynamic braking resistance (DBR) for each phase. Continuous tippling operation with accurate zero positioning of the wagon tippling platform (within ±5 degree) has been established with braking almost at 5% of nominal speed. There is current sharing between the drives. Control of wagon tippling operation is performed with the drives in Current sharing mode due to heavy over-hauling/regeneration by the tippler. Accompanying Figure 4 is a screen shot showing the typical process trend of current sharing of VFD based squirrel cage drive motors according to the system of the present invention.
The mechanical arrangements/modifications has been made for Mounting of new VFD grade motor with higher frame size and shaft diameter in place of existing Slip ring Induction motor by modification in the existing motor base/I-section and re-designing motor-gear Half-Coupling on motor side only to match the same on gear side. The modification was done in the half coupling arrangement on the motor-gear side for introduction of cylindrical motor shaft instead of tapered shaft.
Importantly, a display & annunciation unit is also facilitated to show the number of wagons tippled along with the speed and current taken by the motors providing means for sensor-less counting of wagons tippled and its BCD (Binary coded display) display for quick and correct counting of tippled wagons. Also the encoder based reverse rolling protection scheme/logic with dynamic braking and DC bus regulation is implemented to take care of load sharing between the two motors during heavy over-hauling/ regeneration by the tippler.
It is thus possible by way of the present invention to providing a system for continuous wagon tippling operation without jerk, replacing the earlier slip ring resistance cutting system based wagon tippling operation system which was less accurate and causing jerk

due to stepped speed change, frequent breakdown and high level of noise. The new system has achieved continuous tippling operation with accurate zero positioning of the wagon tippling platform (within ±5 degree) and braking almost at 5% of nominal speed. The system also ensure social benefit resulting from Less Noise and Easy Troubleshooting (Health/operation).

We Claim:
1. A wagon tippler comprising warm redundant tippling control system involving warm redundant Master-Slave configuration for speed and direct torque control with scheme to change over the drive to any configuration adapted for continuous tippling operation with accurate zero positioning of the wagon tippling platform (within +/- 5 degrees) and dynamic braking resistance (DBR) for each phase.
2.A wagon tippler as claimed in claim 1 comprising two numbers VFD grade motors with higher frame size and shaft diameter having motor-gear Half-Coupling on motor side adapted to only match the same on gear side for introduction of cylindrical motor shaft;
VFD (Variable frequency drive) system comprising of position measurement sensors involving multi-turn absolute encoder, incremental encoders for speed feedback;
PLC and VFD with display & annunciator at operator desk and cable extension to control panels for interfacing with multi-point combined cam limit switch (for back up of absolute encoder) coupled with motor-gear system of the tipplerjand
a VFD drive located between other two drives feeding the two VFD motors, which acts as stand-by and can replace any other drive through a changeover scheme.
3. A wagon tippler as claimed in anyone of claims 1 or 2 , comprising Synchronous Serial Interface (SSI) based multi-turn absolute encoder as position measurement sensor.
4. A wagon tippler as claimed in anyone of claims 1 to 3 , wherein encoder based reverse rolling protection scheme/logic comprises dynamic braking and DC bus regulation.
5. A wagon tippler as claimed in anyone of claims 1 to 4, wherein said system is adapted to ensure braking almost at 5% of nominal speed with current sharing between the drives.

6. A wagon tippler as claimed in anyone of claims 1 to 5, comprising a display and annunciation unit for sensor-less counting of wagons tippled and its BCD display.
7. A wagon tippler having an improved warm redundant tippling control system substantially as hereindescribed with reference to accompanying drawings.

A wagon tippler comprising of warm redundant PLC & VFD based digital control system for control of continuous rotary wagon tippling operation is disclosed. This system comprises of VFD grade squirrel cage induction motor mounted with incremental encoder for speed feedback. It has a Model based MASTER-SLAVE configuration for speed and direct torque control with Warm redundant scheme to change over the drive to any configuration. The encoder based reverse rolling protection scheme/logic with dynamic braking and DC bus regulation is in place to take care of load sharing between the two motors during heavy over-hauling/ re-generation by the tippler. Synchronous Serial Interface (SSI) based multi-turn absolute encoder is used as position measurement sensor. The system provides means for sensor-less counting of wagons tippled and its BCD display. Continuous tippling operation is achieved with accurate zero positioning of the wagon tippling platform (within ±5 degree) and braking almost at 5% of nominal speed.