Electrical Troubleshooting Quiz — July 5, 2022


How good are your basic troubleshooting techniques? It’s the start of the shift and a production line won’t start. The trouble ticket says the operator pushed the start button several times and nothing happened.

It’s a production line you’ve never seen before, in an area of ​​the plant you’ve never been in before. Yet it’s your job to find and fix the problem, and they want that thing running as soon as possible.

Where do you begin your investigation and what are your first steps?

Troubleshooting steps

Start by introducing yourself to the operator. Not only is that good for interdepartmental relations, it is good for getting up to speed quickly on the context of the problem. Ask the operator for a quick overview of the system. Then ask the operator to show you where each E-stop is located, even though you should be able to see those due to the distinctive size and color of E-stop buttons.

Now you can start some preliminary troubleshooting. With any system that runs on electrical power, the first thing to check is whether it has power. Production machines have panel lights, and this one should be no exception. On the panel where the operator was pushing the start button, there should be some kind of status light and other pilot lamps. If those are all off, the entire system probably lacks power. If those are on, you at least know there is power to the operator station.

Look at the local disconnect for the motor; is it open or closed? If it is open, the previous operator may have opened it to prevent the line from running due to a parts jam or for some reason like that, but there was a communication breakdown such that the reason didn’t get communicated to this shift’s operator. Discuss this with the operator and ask them to look into that, but first check the line for any problems that would be a reason to shut the line down.

If the disconnect is closed, visually check each E-stop to see if one has been pressed. If it has, first verify with the operator that there is no parts jam or other obvious reason not to restart the line. Then have the operator ensure the controls are set in the Off position. Reset the E-stop and stay near it while the operator tries to start the line.

  • If the line starts with no problem, you’ve solved the trouble ticket.
  • If the line starts and something is clearly wrong (eg, there’s a loud racket coming from the line), slap the E-stop. You’ll have to go down that troubleshooting path to determine what needs to be fixed so the line can run.
  • If the line did not start, you need to keep going down the “Is there power?” troubleshooting path. At the motor disconnect, check for supply power. If it’s not there, go back to the branch circuit overcurrent protection device to see if it’s open. If there is power to the disconnect and power on its load side, then you need to check each major type of load. For example, check the drive motor overload protection devices; if there is PLC control, then ensure the PLC has power.

Troubleshooting production equipment is not simply a technical exercise; Your job isn’t done just because you got it to run again. Any time there is a breakdown in communication or procedure, you need to bring that to the attention of someone who can do something about it. In this case, for example, let’s say the previous operator left the machine with the disconnecting device open but there was nothing passed on to the next shift about that. The maintenance manager needs to know about this communication failure, so that something can be arranged with the production department to prevent such a thing in the future.

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