Beginner guide (986746), страница 17
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Ifany change exists, auxiliary relay 25507 is turned ON.Alarm buzzer output ON.0201Alarm buzzer output.020011001100JME(05)7-228.qINSTALLATION AND WIRING CONSIDERATIONSPLC Power InterruptionsSupply Voltage DropWhen the supply voltage falls below 85% of the rated value, the PLC stops and the output goesOFF.Momentary Power Failure DetectionA momentary power failure lasting less than 10 ms with an AC power supply and 2 ms with a DCpower supply is not detected and the CPU continues to operate.A momentary power failure lasting longer than 10 ms with an AC power supply and 2 ms with a DCpower supply may or may not be detected in an uncertain area.When a momentary power failure is detected, the CPU stops operating and the output goes OFF.Automatic RestartWhen the supply voltage recovers to a value higher than 85% of the rated value, operations resumesautomatically.Under10 ms (2 ms)OverDuration of power interrupt(Below 85% of rated voltage)NormaloperationOperationmay stopAll outputs go OFF whenOperations stop.NoteThe PLC may repeat stop/start operations if the supply voltage of less than 85% of the rated valuegradually goes up or down.If this affects the equipment, etc., provide a protection circuit which shuts off the output if thesupply voltage is not above the rated value.Time Up to Start of OperationThe time from when the power supply is turned on to when the operation starts varies depending onthe operation conditions such as power supply voltage, configuration, ambient temperature, etc.
Theminimum time is approximately 300 ms.8-18.qINSTALLATION AND WIRING CONSIDERATIONSInstallation Site ConsiderationsThe PLC is resistant to harsh conditions and highly reliable, but installing the PLC in a favourablesite will maximize its reliability and operating lifetime.•Installation site conditionsAvoid installing the PLC in a site with any of the following conditions.• A site in direct sunlight• A site where the ambient temperature exceeds the 0°C to 55°C range• A site where the relative humidity exceeds the 10% to 90% RH range• A site where condensation occurs due to sudden temperature changes• A site with corrosive gases, flammable gasses or salt• A site with water, oil, or chemical sprays• A site subjected to direct vibration or shockBe sure that the conditions at the installation site conform to the PLC’s general specifications.qPanel/Cabinet InstallationConsider PLC operation, maintenance, and surrounding conditions when installing the PLC in apanel or cabinet.OverheatingThe operation temperature range for the PLC is 0°C to 55°C.
Be sure that there is adequateventilation for cooling.•••Allow enough space for air circulation.Do not install the PLC above equipment that generates a large amount of heat, such asheaters, transformers, or large resistors.Install a cooling fan or system when the ambient temperature exceeds 55°C.ControlPanelFanCPM1Air VentElectrical NoisePower lines and high-voltage equipment can cause electrical noise in the PLC.• Do not install the PLC in a panel or cabinet with high-voltage equipment.• Allow at least 200 mm between the PLC and nearby power lines.200 mm min.CPM*A200 mm min.CPM*A-CPM1A and CPM2A.8-28.qINSTALLATION AND WIRING CONSIDERATIONSGeneral Precautions for WiringI/O Lines NoiseDo not run CPM1A I/O lines in the same duct or conduit as power lines.Handing DuctsLeave at least 300 mm between the power cables and the I/O or control wiring, as shown in thefollowing diagram.CPM*A I/O lines300 mm minControl cables andCPM*A powerlines300 mm minPower cablesFloor DuctsLeave at least 200 mm between the wiring and the top of the duct, as shown in the followingdiagram.CPM*A I/O linesControl cables andCpm*A power linesPower cablesMental plate (iron)200 mm minConduitSeparate the CPM*A I/O lines, power and control lines, and power cables, as shown in thefollowing diagram.CPM*A I/O linesControl cables andCPM*A power linesPower cablesCPM*A-CPM1A and CPM2A.8-38.INSTALLATION AND WIRING CONSIDERATIONSGroundingBe sure to ground the functional earth and protective earth terminals together to less than 100Ω inorder to protect against electric shock and incorrect operation from electrical noise.
Be sure to sue awire of at least 2 mm2 for grounding.Ground to 100Ω max.Crimp ConnectorsAlways use crimp connectors for the CPM*A’s power lines and I/O lines or else use a single-wireline (instead of a stranded wire). Stray wire strands could accidentally short out.Use M3 terminal screws and tighten the screws securely (0.5 to 0.6 N-m).Recommended Terminal: Use the terminal shown below.Fork terminal6.2 mm max.qPower Supply Wiring100 to 240 VAC Power SupplyWire a separate circuit for the CPM*A’s power supply circuit so that there isn’t a voltage drop fromthe inrush current that flows when other equipment is turned on.When several CPM*A PLCs are being used, it is recommended to wire the PCs on separate circuitsto prevent a voltage drop from the inrush current or incorrect operation of the circuit breaker.Use twisted power supply wires to prevent noise from the power supply lines.
Adding a 1:1 isolatingtransformer reduces electrical noise even further.IsolationtransformerACpowersupplyTwist the wires. The cross-sectional areaof each wire must be 2 mm2 min.Breaker8-48.qINSTALLATION AND WIRING CONSIDERATIONSCountermeasure for Inductive LoadWhen switching an inductive load, connect an surge protector, diodes. etc. parallel with the load orcontact as shown below.CircuitCR methodCurrentAC DCYes YesDiode methodNoYesVaristor methodYesYesCharacteristicRequired elementIf the load is a relay or solenoid,there is a time lag between themoment the circuit is opened andthe moment the load is reset.If the supply voltage is 24 or 48V,insert the surge protector inparallel with the load. If thesupply voltage is 10 to 200V,insert the surge protector betweenthe contacts.The capacitance of the capacitormust be 1 to 0.5µF per contactcurrent of A and resistance of theresistor must be 0.5 to 1Ω per contactvoltage of V.
These values, however,vary with the load and thecharacteristics of the relay. Decidethese values from experiments, andtake into consideration that thecapacitancesuppressessparkdischarge when the contacts areseparated and the resistance limitsthe current that flow into the loadwhen the circuit is close again.The dielectric strength of thecapacity must be 200 to 300V. If thecircuit is an AC circuit, use acapacitor with no polarity.The reversed dielectric strength valueof the diode must be at least 10 timesas large as the circuit voltage value.The forward current of the diodemust be the same as or larger than theload current.The reversed dielectric strength valueof the diode may be two to threetimes larger than the supply voltageif the surge protector is applied toelectronic circuit with low circuitvoltages.The diode connected in parallelwith the load changes energyaccumulated by the coil into acurrent, which then flows into thecoil so that the current will beconverted into joule heat by theresistance of the inductive load.This time lag, between themoment the circuit is opened andthe moment the load is reset,caused by this method is longerthan that caused by the CRmethod.The varistor method prevents theimposition of high voltagebetween the contacts by using theconstant voltage characteristic ofthe varistor.
There is time lagbetween the moment the load isreset.If the supply voltage is 24 or 48V,insert the varistor in parallel withthe load. If the supply voltage is100 to 200V, insert the varistorbetween the contacts.When switching a load with a high inrush current such as an incandescent lamp suppress the inrushcurrent as shown below.8-58.INSTALLATION AND WIRING CONSIDERATIONSCountermeasure 1OUTCountermeasure 2L+OUTRL+RCOMProviding a dark current of approx.
onethird of the rated value through anincandescent lampCOMProviding a limiting resistor8-69.qMAINTENANCE AND TROUBLESHOOTINGThe PLC CycleThe overall flow of PLC operation is as shown in the following flowchart. The PLC is initializedinternally when the power is turned on. If no errors are detected, the overseeing processes, programexecution, I/O refreshing, and peripheral Device servicing are executed consecutively (cyclically).The average cycle time can be monitor from a Peripheral Device.Power applicationInitialization processesInitializationCheck hardware andProgram MemoryCheck OK ?Set error flags andactivate indicatorsALARM(flashing)ERRORORALARM?OverseeingprocessesPreset cycle timemonitoring timeExecute user programERROR(lit)End of program ?NoProgramexecutionCycletimeCheck cycle time settingMinimumcycle time set ?Wait until minimumcycle time expiresNoCycle timeprocessingComputer cycle timeNoteRefresh input bitsand output terminalsI/OrefreshingService peripheral portServiceperipheralportInitialization process include cleaning the IR, SR, and AR areas, pre- setting system timers, andchecking I/O Units.9-19.qMAINTENANCE AND TROUBLESHOOTINGSelf-diagnosis FunctionsThe PLC is equipped with a variety of self-diagnosis functions to help identify and correct errorsthat might occur an reduce down time.PLC errors are divided into 2 categories based on the severity of the errors.
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