IMPLEMENTATION OF PROGRAMMABLE RELAY FOR CONTROL AND TRACKING OF CONVEYOR BELTS

Transcription

1 Volume 119 No , ISSN: (on-line version) url: ijpam.eu IMPLEMENTATION OF PROGRAMMABLE RELAY FOR CONTROL AND TRACKING OF CONVEYOR BELTS T.Rampradesh 1, R.Bhavadharani 2, V.Divya 3, M.Divya Kumari 4 Associate Professor/EEE, IFET College of Engineering, Villupuram, India 1 UG Scholar/EEE, IFET College of Engineering, Villupuram, India 2,3,4 Abstract-Automation is one of the highest needs of any industry for its consistent growth and survival in the market. Automation can increase the rate as well as maintain accuracy in the work output. Conveyor belts are widely used in many applications and in variety of industries like mining, food processing, pharmaceuticals, packaging, etc., In this paper we have developed an automatic conveyor belt tracking and monitoring system by which we can consistently monitor the belt assembly and automatically shut down during over loading conditions. The system can be again restarted either by human interface or automatically by using a fault detection system. The system can detect faults and shut down within a period of 5 seconds. The system was simulated in PLC and a scale down model was developed and experimentally verified using a ZEN-10C1DR-D-V2 programmable relay. The performance of the system was tested by introducing an instant fault and the system response was found to be satisfactory. The system can be implemented in any application wherein we design a controller based upon the feedback from pulse counter. Keywords PLC, Programmable relay, Conveyor belt, pulse counter. I. INTRODUCTION A conveyor belt assembly is defined as mechanical handling equipment that moves materials from one location to another. Conveyors are especially useful in applications involving movement of heavy materials and movement of materials in a process oriented organization from one point to another. Conveyor belt system ensures fast and efficient transportation, for a wide variety of materials, which make them an attractive choice in many fields like material handling and packaging industries. Variety of conveyor belt systems are available and are used according to the various needs of different process oriented industries. Monitoring of conveyor belts are very important for automation. [1] Fig.1.Simple conveyor layout II. MAINTENANCE OF CONVEYOR SYSTEM A conveyor system is the main central equipment to a company s ability to effectively move its product in a timely manner. Increasing the life of a conveyor system involves: choosing the right conveyor type for the right application, the right system design and paying attention to regular and periodic maintenance of the motors connecting the conveyor belts. Any disruption of its operation can be too costly and most downtime can be avoided by taking necessary steps to ensure the system operation at its peak performance. Monitoring of the overall system including the motors and all the associated components is very important for effective and continued operation of the belt conveyor system. Supervising the automated systems is done by using a variety of methods. [2] [7] A. Poor take-up adjustment: The chain take-up device ensures that the chain is pulled tight as it leaves the drive unit. In the case of belt conveyors, a poor take-up may cause drive unit damage or may let the belt slip off of the side of the chassis. Therefore constant monitoring of the belt assembly is required. B. Lack of lubrication: Chain bearings require lubrication in order to reduce friction. The energy required to pull the chain can double if the bearings are not lubricated. This can cause the system to overload by either its mechanical or electrical overload protection. On conveyors that go through hot 655

2 ovens, lubricators can be left on constantly or set to turn on every few cycles. C. Contamination: Paint, powder, acid or alkaline fluids, abrasives, glass bead, steel shot, etc. can all lead to rapid deterioration of track and chain. Once a foreign substance lands on the raceway of a bearing or on the track, pitting of the surface will occur, and once the surface is compromised, wear will accelerate. D. Product handling: In conveyor systems that may be suited for a wide variety of products, such as those in distribution centres, it is important that each new product be deemed acceptable for conveying before being run through the materials handling equipment. Boxes that are too small, too large, too heavy, too light, or too awkwardly shaped may not convey, or may cause many problems including jams, excess wear on conveying equipment, motor overloads, belt breakage, or other damage, and may also consume extra man-hours in terms of picking up cases that slipped between rollers, or damaged product that was not meant for materials handling. E. Drive train: Notwithstanding the above, involving take-up adjustment, other parts of the drive train should be kept in proper shape. Broken O-rings on a Line shaft, pneumatic parts in disrepair, and motor reducers should also be inspected. Loss of power to even one or a few rollers on a conveyor can mean the difference between effective and timely delivery and repetitive nuances that can continually cost downtime. F. Bad belt tracking or timing: In a system that uses precisely controlled belts, such as a sorter system, regular inspections should be made that all belts are travelling at the proper speeds at all times. While usually a computer controls this with Pulse Position Indicators, any belt not controlled must be monitored to ensure accuracy and reduce the likelihood of problems. Timing is also important for any equipment that is instructed to precisely meter out items, such as a merge where one box pulls from all lines at one time. If one were to be mistimed, product would collide and disrupt operation. Timing is also important wherever a conveyor must "keep track" of where a box is, or improper operation will result. III. MONITORING OF CONVEYOR BELTS A conveyor belt is the carrying medium of a belt conveyor system (often shortened to belt conveyor). Conveyors used in industrial settings include tripping mechanisms such as trip cords along the length of the conveyor. This allows workers to immediately shut down the conveyor when a problem arises. Warning alarms are included to notify employees that a conveyor is about to turn on. PLC has been effectively used in automation of industries [3]. A MicroLogix-1000 PLC-based controller was developed to automate the pneumatic press. [4] The methods to monitor conveyor belts are; Visual inspection X-ray (portable camera) Transmitter-receiver system Leakage field measurement Magnetic resistance Opto-electronic imaging X-ray (stationary, continuous) IV. PROPOSED SYSTEM A simple belt conveyor system consists of two or more pulleys. An endless loop of carrying medium and the conveyor belt rotates about them. To move the belt and the material it carries forward, one or both pulleys are powered. The powered pulley is called drive pulley, the unpowered one is known as idler pulley. Fig.2. Belt conveyor mechanism The drive pulley consists of an ac motor that operates with enough torque and speed to pull the belt and the materials placed over the belt. The proposed system is based on a type of belt tracking system, in which the speed of the belt is monitored by counting the pulses across a particular point. Under normal operation the system operates in a normal speed with predefined number of pulses. When the belt is heavily loaded, the number of pulses is reduced and is sensed by the pulse counter, which gives a feed back to 656

3 the programmable relay. Under abnormal conditions like over speed or low speed due to invariable load conditions the programmable relay shuts down the belt drive and protects the belt from damage. Therefore the system operates on a closed loop by which the system is closely monitored periodically. The speed of the motor is the main parameter that is to be sensed and monitored. The speed sensor can effectively work on any abnormal conditions and operate the system effectively. Counter Programmable relay Feed back Belt drive AC motor Fig.3. Block diagram of proposed system VI. EXPERIMENTAL VERIFICATION A. Programmable logic controller: The combination of Programmable Logic Controller (PLC) and Relay Logic contributes a lot for automation. Programmable relays operate on a specific logic and can feed the output to a controller. To some extent, a PLC has its action for returning mechanical device relays logic and thus can be used in the field of automation for various applications. PLCs are typically used for industrial firms and supply input moreover as output. Once this program is running, the machine must scan the input whereas the output may be determined into relay logic. The ZEN-10C1DR-D-V2 is a Programmable Relay with increased functionality and higher precision. This single CPU unit easily provides relay, timer, counter and time switch functions. Wiring work is greatly reduced because separate wiring is not required for devices such as timers and counters. Programs can be easily written, saved and monitored by personal computer. V. SIMULATION A program loaded into PLC systems in machine code, a sequence of binary code numbers to represent the program instructions. Assembly language based on the use of mnemonics can be used, and a computer program called an assembler is used to translate the mnemonics into machine code. High level Languages (C, BASIC, etc.) can be used. The sensing signals from two sensors fixed at two ends of conveyor system are given as the inputs to the programmable relay. The block contains the threshold set value as 2 pulses/2 second-on and 1pulses / 2 second-off. When these two signals are high, it will enable the output. A sample programming block is shown in the Fig.4. Fig. 4.ZEN-10C1DR-D-V2 The ZEN-10C1DR-D-V2 consists of input voltage of 100 to 240 V AC, 12 to 24 V DC and 10 input output points. The connection diagram of the relay to a scale down model of a conveyor belt assembly is shown in Fig.5. Fig.4. Sample programming 657

4 Fig.5.Scale down model of the proposed system 1-Programmable logic controller 2-Turn ON relay 3-Turn OFF relay 4-Rectifier 5-Piezo electric buzzer 6-AC motor 7-speed sensor 8-Cconveyor belt system 9-Fault adjustment screw The scale down model consists of speed sensors, relay coils, drive circuit, single phase ac motor, buzzer and the programmable relay. B. Relay coil: The electronic relay is a type of an electronic switch that opens or closes the circuit contacts by using electronic component without any mechanical operation. These are high quality Single Pole - Double Throw (SPDT) sealed relays. They are used to switch high voltage, and/or high current devices. This relay's coil is rated up to 12V, with a minimum switching voltage of 5V. The contacts are rated up to 5A (@250VAC, 30VDC. Two such electronics relays are connected in the hardware model. 1) Turn ON relay: The major function of this relay is to switch on the motor and build the connection between the motor and the drive. This relay is connected via main supply relay programmable relay motor. 2) Turn OFF relay: The major function of this relay is to switch off the motor and break the connection between the motor and the drive. This relay is connected via speed sensor Programmable relay relay main supply. C. Buzzer Volt: The piezo buzzer produces sound based on reverse of the piezoelectric effect. The generation of pressure variation or strain by the application of electric potential across a piezoelectric material is the underlying principle. These buzzers can be used alert a user of an event corresponding to a switching action, counter signal or sensor input. [6] The buzzer is connected in line with the 2 nd relay coil. As soon as the relay breaks the circuit between the motor and the main supply the buzzer is activated for user interface. D. Speed sensor: The major goal of the speed sensor is to check the rate of an electric motor. The module is used in association with the programmable relay for motor speed detection and pulse count measurement. The green indicator (LED1) indicates the presence of voltage applied, and the red indicator (LED2) monitors output of the motor speed sensor module. The working voltage of the module is 4.5 to 5.5 volt dc. E. AC motor: The single phase AC motor is used to drive the belt assembly. The motor is connected with its associated speed sensor module. Control of induction motor by PLC is widely used in many industries. [4] A scale down model of a conveyor belt assembly was developed. A mechanism to create an instant tightening of the belt was arranged. The motor is switched on and the conveyor belt system was operated. A fault was created instantly and the total system was shut down with a beep sound. Initially the speed sensor sensed the reduction in pulses and gave the feed back to the programmable relay and the 2 nd relay broke the circuit between the motor and the buzzer was activated. The belt was loosened and the 1 st relay built the circuit and the circuit came into normal operation. The buzzer was stopped. VII. CONCLUSION The system operation was satisfactory and the motor was turned off appropriately. The system came to rest in less than 5 seconds. The system is cost effective and accurate results can be obtained. The system can be implemented for the protection of conveyor belts and can be used in any application. Further the system could be modified with a PC interface and automation can further be developed. Specifications like speed, weight of the materials, etc., can be closely monitored by using recent technologies like IoT, Zigbee, etc., 658

5 VIII. REFERENCES: [1] Dhiraj Patil, et.al., Design and Fabrication of PLC Based Conveyor System with Programmable Stations, International Journal of Analytical, Experimental and Finite Element Analysis (IJAEFEA), Issue. 3, Vol. 4, Sept [2] Yassine Qamsane, Mahmoud El Hamlaoui, et.al., A Model-Based Transformation Method to Design PLC-Based Control of Discrete Automated Manufacturing Systems, 4 th International Conference on Automation, Control Engineering and Computer Science (ACECS ) Proceedings of Engineering and Technology PET, Vol.19, pp [3] Kiran A. Gupta, Neha Armani, Design and Implementation of PLC Based Industrial Application Prototypes, Indian Journal of Science and Technology, Vol 10(35), [4] Ranjeeta singh, H.K.Verma, Development of PLC based Controller for Pneumatic Pressing Machine in Engine Bearing Manufacturing plant, 6 th International conference on Smart Computing and Communication, ICSSC [5] A.R. AL Ali, M.M. Negm, et.al., A PLC based power factor controller for a 3 phase induction motor, IEEE transactions, [6] Miss. Dhotre Smita Kishor, Miss.Deshpande Pooja Raghunath, et.al., PLC based home security System, International Engineering Research Journal (IERJ), Page , [7] Fran cois Bonne, Mazen Alamir, et.al., Experimental investigation of control updating, period monitoring in industrial PLC-based fast MPC: Application to the constrained control of a cryogenic refrigerator, Control Theory Tech, Vol. 15, No. 2, pp , May

6 660