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PowerPoint ® Presentation Chapter 11 Troubleshooting PLC Hardware PLC Hardware Problems Power Supply Problems Troubleshooting PLC Input Sections or Modules.

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Presentation on theme: "PowerPoint ® Presentation Chapter 11 Troubleshooting PLC Hardware PLC Hardware Problems Power Supply Problems Troubleshooting PLC Input Sections or Modules."— Presentation transcript:

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2 PowerPoint ® Presentation Chapter 11 Troubleshooting PLC Hardware PLC Hardware Problems Power Supply Problems Troubleshooting PLC Input Sections or Modules Troubleshooting PLC Output Sections or Modules

3 Chapter 11 — Troubleshooting PLC Hardware PLCs are designed for use with all common supply voltages, such as 230 V, 208 V, 115 V, and 24 V.

4 Chapter 11 — Troubleshooting PLC Hardware When problems occur with PLC power supplies, input and/or output modules, or any system components, a check of the supplied power should be performed over time using a test instrument with a recording function.

5 Chapter 11 — Troubleshooting PLC Hardware Short circuits typically occur when conductor insulation is damaged, which allows a current-carrying conductor to come in contact with any grounded noncurrent- carrying metal parts. An overload is an overcurrent condition that occurs when circuit current exceeds normal PLC operating current and/or designed circuit current.

6 Chapter 11 — Troubleshooting PLC Hardware Voltage measurements can be used to test fuses that are connected to a circuit.

7 Chapter 11 — Troubleshooting PLC Hardware Resistance measurements are used to test fuses that have been removed from a circuit.

8 Chapter 11 — Troubleshooting PLC Hardware Circuit breakers perform the same function as fuses and are basically tested the same way.

9 Chapter 11 — Troubleshooting PLC Hardware Control transformers are typically used to step down 115 VAC, 208 V, 230 V, or 460 V to 12 VAC or 24 VAC for control circuit use in a PLC enclosure.

10 Chapter 11 — Troubleshooting PLC Hardware When the power rating of a transformer is exceeded by placing too great a load on the transformer, the voltage on the secondary side will start to decrease and circuit problems will develop.

11 Chapter 11 — Troubleshooting PLC Hardware PLCs can have a single fixed voltage rating or a dual voltage rating. Dual voltage rated PLCs (115/230 VAC) have a selector switch (or movable links) to set the PLC to one of the possible voltage ratings.

12 Chapter 11 — Troubleshooting PLC Hardware Output power supplies of PLCs are typically used to supply voltage to input devices connected to the PLCs.

13 Chapter 11 — Troubleshooting PLC Hardware The listed current rating of a power supply must be accepted as the maximum amount of current that can safely be provided from a PLC output power supply.

14 Chapter 11 — Troubleshooting PLC Hardware When an input signal is sent to a PLC, the PLC conditions, filters, and optically isolates the signal.

15 Chapter 11 — Troubleshooting PLC Hardware When troubleshooting PLC input sections, programming diagrams and manufacturer troubleshooting charts indicate how input devices are connected and which output components are being controlled.

16 Chapter 11 — Troubleshooting PLC Hardware Testing input modules requires that power supplies and input devices be tested and that status lights of input modules and symbols on computer monitors be checked.

17 Chapter 11 — Troubleshooting PLC Hardware All input devices and the PLC program must operate correctly in order for an automated circuit to operate properly.

18 Chapter 11 — Troubleshooting PLC Hardware Proper heat sinking and cooling is required with solid-state devices to eliminate any potential heat problems.

19 Chapter 11 — Troubleshooting PLC Hardware The current that flows through an “open” solid- state switch is called leakage current. Leakage current can turn on the input circuitry of a PLC, affecting system operation.

20 Chapter 11 — Troubleshooting PLC Hardware Testing the leakage current of solid-state devices requires that the OFF state leakage current measurement be compared to the specified minimum operating current of the PLC input module.

21 Chapter 11 — Troubleshooting PLC Hardware Signals from the CPU of a PLC are sent through logic circuits to output section status lights and opto-isolation circuits before being sent to output terminals.

22 Chapter 11 — Troubleshooting PLC Hardware When troubleshooting PLC output sections, programming diagrams and manufacturer troubleshooting charts help the troubleshooter/technician understand how the input devices are connected and which output components are being controlled.

23 Chapter 11 — Troubleshooting PLC Hardware Testing output modules requires that power supplies and output components be tested and that status lights of output modules and symbols on computer monitors be checked.

24 Chapter 11 — Troubleshooting PLC Hardware All output components and the PLC program must operate correctly in order for an automated system to operate properly.


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