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Drive Repair process of Allen bradley Powerflex40 AC Drives

Kontroltek’s Guide to Common PLC Repairs & Faults

A Programmable Logic Controller (PLC) acts as the brain for many industrial-based, automated machinery systems. Utilised by various industries and sectors, the primary function of a PLC is to translate commands into language that industrial parts can understand. For example, without a PLC, a motor would not be able to execute the command input by the user through an HMI or computer.

Able to conquer more complicated tasks, PLCs are now more intricate than ever. Subsequently, more modern PLCs can command expansive machinery systems for great lengths of time. As a result of these extended operating times, it is not surprising that these PLCs can often present faults.

This blog explores the common PLC issues often identified by our Kontroltek engineers during their repair and servicing assignments.

Parker AC890 AC Drive Unit in for repair with Kontroltek
Kontroltek have a wide range of in-house built test rigs, to conduct thorough testing on our PLC Repairs.

PLCs. Identifying Common Faults

There are multiple ways for a PLC system to fail, of which many can significantly increase your operational downtime and impact business efficiency. Generally, faults can vary in severity and rarity. Our engineers have identified an array of common PLC failures, from which we have curated the handy list found below.

  • Configuration Errors (Software)
  • Wiring Issues (Hardware)
  • Component Failure
  • Power Supply Issues
  • External Interference
  • Temperature Regulation Issues
  • Communication Errors

Many of these faults and failures can be avoided by conducting regular inspections performed by factory engineers or PLC specialists. Doing so will allow your business to identify issues early and develop solutions to assist you in the future.

However, some issues are unavoidable. Power surges and blackouts can be detrimental to your PLC’s health, damaging internal components whilst eradicating any commands or programmes installed onto the unit. Fortunately, in addition to our PLC repair services, Kontroltek also provides PLC software backup services that can help to limit the damage and minimise operational downtime.

Whilst our Kontroltek engineers highlighted an extensive list of PLC faults, this blog will focus on the three most commonly identified in our workshop. These are Input & Output (I/O) System Failures, Power Supply Failures and Communication Errors.

Input & Output (I/O) System Failures

PLC input/output failures are one of the most common faults that our engineers repair. These repairs often require a period of troubleshooting, as it is never openly obvious where the failure is. Throughout this process, our engineers will aim to identify the disconnection between the internal situation (what the PLC believes is happening) and the external situation (what is happening).

This approach involves examining the relationship between the physical I/O modules and the I/O instructions within the PLC program. From this examination, Kontroltek engineers will be able to isolate a single I/O module and use a programme monitoring device to check its internal status. Completing this process will determine which module is faulty.

Power Supply Failure

Like most electronic equipment, a PLC device requires continuous and stable power to function correctly. Sudden interruptions or fluctuations this power supply can result in the PLC shutting down shutting down incorrectly and data loss. In many cases, these power faults are out of your control, blackouts and grid failures being some examples.

Regularly reviewing your PLC unit for issues such as loose connections or deteriorated cables is a great way to avoid unwanted power failures. Furthermore, installing a backup power source is also an option to prevent data loss in your PLC.

Communication Errors

To allow a PLC to function correctly, it needs constant communication with external peripherals and other equipment, such as HMIs. Generally, these connections are made possible by Ethernet cables. These cables must be able to establish stable, secure and consistent connections for extended periods.

If these connections were to fail, any devices operating from the PLC unit would no longer be able to complete their programmed functions, resulting in operational downtime. It is advisory that PLC systems undergo inspections regularly. Ensuring that communication networks are established correctly, any devices connected to the PLC are well-suited to the system and functioning as they should be, and firmware updates are installed when made available.

Beckhoff Test rig for stress testing drive repairs

In Summary

Whilst PLCs can develop faults and issues relatively easily, Kontroltek is always on hand to offer its industrial PLC repair services. Our dedicated team of PLC repair experts have years of experience and can diagnose, repair and service your part with ease.

To help maintain the condition of your PLCs there are a few simple steps that your business can take. Firstly, machinery operators should confirm that all parts are connected correctly. Secondly, ensure that you maintain an adequate environment of operation. Achieve this by removing all possible interference with the PLC, including non-essential electronic equipment and excess moisture or heat.

Sometimes, a good maintenance routine is not enough, and sadly PLCs or other industrial-based electronic parts can still become faulty. Subsequently, Kontroltek also offers repairs for these additional parts; PCBs, HMIs, Drives, Robots, Electric Motors and much more. We aim to help to keep your business operating as smoothly and efficiently as possible. Also, our engineers can repair parts from a variety of popular brands such as Allen-Bradley, Siemens and Mitsubishi Electric.

If you would like to learn more about how Kontroltek can help your business with its PLC faults and repairs, speak to one of our sales team using the contact details below or get in touch with us through our website. All of our repairs are fully tested (if applicable) before leaving our workshop and come with a 12-month warranty.

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