Application of MITSUBISHI PLC PLC Application MITSUBISHI in PLC Application MITSUBISHI wire rope type grille decontamination machine on
Wire rope type grille decontamination machine is a high degree of automation of the sewage treatment equipment for floating in large sewage interception and clearance. Cihu Lake in Huangshi city sewage treatment plant put into use in 2003 three sets of such equipment, the core of the control system with FX1N -40MR type of Japanese Mitsubishi Co production of programmable controller (I/O input 28, output 18 points), with proximity switch (induction distance of 5mm and l0mm) and FDU81 type liquid potentiometer as signal acquisition device. 3 years of practice has proved that the PLC control is safe and reliable, and meets the requirements of the automation of wastewater treatment process.
First, the introduction of equipment
Grille decontamination machine mainly consists of driving device, differential mechanism, slag discharging mechanism, cleaning, grab rails, gate frame, maintenance platform and electric control device. There are three wire ropes each of this type, winding in the same drum, on both sides of the wire rope traction grab slide up and down along the guide rail, driven by a 2.2kW lifting motor; a middle wire rope grab control opening and closing, opening and closing by another 0.75kW motor drive, so grab and lifting harrow opened and closed separately by two independent motor drive, the main equipment structure shown in figure 1. To grab the upper and lower limit switch, wire rope, rope rope and rake in place are equipped with open and close pairs, together with PLC controller to realize the automatic slag removal action. That is a closed grab downward rake rake the uplink operation timing shutdown a slag discharging time down.
Two, PLC control process
1 grab down. Before starting the grab in the starting position, promotion in place close to the switch on normally open closed X6. Select manual or automatic switch, which is normally open or closed X15 X16, press the start button, normally open X20 is closed, auxiliary relay M392 is connected, the lifting motor start, grab down.
2 open rake. The T0 timer is switched on time delay 2S T0 after the closing of the normal open point, M393 is switched on, the opening and closing of motor starting, grab a harrowing. Open rake in place, open the rake in place close to the switch is switched on, the normally closed point X7 off, open and close the motor to stop running.
3 closed rake. Grab down to the bottom of the pool, closed in place near the trailing switch is switched on, is normally open X4 closed, M0 is switched on, the lifting motor to stop running, and normally open M0 closed, M394 electric hoist, start the motor, closed grab rake. When the closed rake is in place, the close rake is in close proximity to the switch, normally open point X5 is closed, and the M1 is switched on, and the motor stops running.
4 grab up. Close the rake in place, normally open closed M1, M395 power, lifting motor running, grab upward, lifting in place, normally open X6 closed, M2 is switched on, the lifting motor to stop running.
5.slag discharge. Grab up in place after the delay 3S, the differential mechanism and slag discharge waste discharged into the car bodies themselves will run at shutdown timer timer and work at the same time, thus a work cycle end.
Three, PLC control features and functions
1 to achieve a series of accurate cleaning action. Grille decontamination machine is discontinuous operation, through the PLC internal timer, strictly control the running time, decontamination machine downtime and slag discharge time, all output signals can be sent to the central control room, remote control, convenient operation of the personnel on duty at night.
2 loose rope protection. Grab the uplink and downlink in the process, when encountering an obstacle, but did not appear loose rope rake decentralization in place, this is a non normal state (rake does not reach the bottom of the pool). This machine has a PLC internal counter C0 down loose rope times, which record the number of times this state occurs within a specified period of time, such as reaches the preset value, is normally open C0 closed, M104, alarm signal output and control output relay,
3.open and close rake protection. When obstacles appear rake, rake closed grab open process, open and closed position switch can not rake rake on time. The PLC set of T1, T2,
4.flexible control operation according to the difference of the liquid level. When a large number of intercept residue, and grille remover liquid level appeared height difference is large, even if in the shutdown state, also must be turned on, therefore in the automatic working state, grate discharge machine is controlled by the level difference operation controller and the timing of the time,
5.overload protection. When the equipment is mechanical overload or motor overload and other failures, X2 and X10 closed, M100 power, alarm and control the corresponding relay output. In each action program is provided with a normally closed point X17, emergency stop button after the start, all the normally closed point X17 off, the corresponding motor to stop running
Four, installation and use of matters needing attention
1.PLC requirements of the ambient temperature at 0~55 degrees is appropriate, the installation can not be placed in the heat of the large components under the ventilation cooling space should be large enough. If the surrounding environment is more than 55 degrees, it should be installed electric fan forced ventilation.
2 in order to suppress the interference of the power supply and the input and output ends, the PLC should be given a special ground wire. Grounding should be separated from the grounding of power equipment (such as motor), if not up to this requirement, it must be done with other equipment public grounding, and other equipment is prohibited in series grounding.
3 requirements for power supply. PLC power supply for the 50Hz, 220 (1 + 10%) V of the AC. For the power line interference, should install a shield with the ratio of the isolation transformer 1:1, and then access PLC. If the quality of the field power supply can not meet the above requirements, it is necessary to set a high precision voltage stabilized power supply.
4.PLC in use will be due to external interference, back-up battery depletion and hardware and other factors, so that the internal process is lost. Once such a situation, if not in time to re load the original program, it will cause a total paralysis of the device, which requires a good program backup.
Five, the conclusion
The application of PLC in automatic control of wire rope type grille decontamination machine, realize the grab down, open and close, lifting, rake rake slag discharge five mechanical action, running as expected to set the time, until the limit of each action close to switch to the signal. The operation practice shows that compared with the traditional relay control, PLC saves a lot of time relay, counter, step control switches and other equipment, improve the accuracy and reliability of automatic control, and ensure the safety operation of the controlled equipment, achieved good economic and social benefits.