Being able to analyze strong evidence like “appears to be developing a problem,” figure out what’s really going on, and decide on the best course of action is one of the most satisfying aspects of being an electrician. A technician feels extremely satisfied after solving a complex piece of equipment’s problems. This satisfaction can be attained by developing an effective troubleshooting plan and following it.
An overview of a straightforward but efficient technique for analyzing an electrical issue is provided in this article.
Prior to considering a repair action, it is crucial to respond to or complete as many of the specified things as possible for a high-cost repair like a boiler feed pump. Reviewing the equipment’s current signature analysis (CSA) and vibration analysis material history was the consequence of using the first step. During this evaluation, it was discovered that both of the motors powering the pump’s amplitude of the pole pass frequency in the CSA had increased. However, neither mechanical nor Electrical troubleshooting issues were suggested by the vibration analysis.
You can now comprehend the malfunction because you have recognized the technical resources and equipment operation.
Understanding the issue
Understanding the malfunction entails knowing how or what the process is, as well as which part of the process is malfunctioning. Respond to these inquiries:
How is the procedure meant to operate?
What isn’t working the way it ought to?
Why would these outcomes or malfunctions occur?
Applying step 2, operations have not reported a problem with the boiler feed pump in issue, but the field technicians have trended a potential abnormality using predictive techniques. The pole pass frequency was found to be increasing upward, and potential explanations were rotor flaws, bearing misalignment, magnetic offset, or anomalous load fluctuations.
Decide which factors need to be assessed.
It is important to have a thorough grasp of the discrepancy and the signals that influence the suspected component in order to decide which parameters should be investigated. Which input signals are used to operate the component? What output should we anticipate from the questioned circuit? Is it possible to verify a temporal delay, a sequence, or a set point?
Identify the issue’s root cause.
The technician must isolate the problematic component using the recorded data, evaluate the circuit parameters, isolate the circuit by group when working with a complex circuit, and then isolate the problematic component using the isolated components.
A current profile comparison between two similar machines is one test that is advised for validating a potential abnormality and determining its severity. This is also known as a process analysis test.” Current samples from two identical devices are displayed in Fig. 1. A single channel of RMS encapsulated current is recorded for up to 60 seconds during the MCEMAX in-rush/start-up test. The test generates a digital RMS strip chart with a sampling rate of 3600 samples per second.
Repair or correct the component.
Based on the recorded data, correct or repair the component that was found to be damaged. Make the circuit’s necessary repairs. Step 5 might be finished with minor tweaks or a full component replacement.
The technicians examined the two motors for the boiler feed pump and discovered that one motor had bent or damaged rotor bars. The elevated pole pass frequency indicators during the current signature analysis meant that the rotor damage was not unexpected. However, given that both of the motors had high values, why was one of the rotors absent? Since both motors were attached to the same shaft, technicians believed that it would not be unusual for the elevated pole pass frequency of one motor to be communicated via the shaft to the other motor.
Check the repair.
Once the fix is finished, check it. Make sure that the machinery is working as it should. Test the system once again to ensure that everything is operating as it should and that there are no other issues.
Retest to confirm that the installation won’t lead to the same failure mechanism in the future after the boiler feed pump motors have been repaired and installed, or after new motors have been installed. In a different illustration, a 460 V ac induction motor’s connecting box contained a high-resistance joint that was found (see “High Resistance Connection Test Results”). The motor lugs were changed and retaped, the resistive imbalance decreased by 3%, and the warning was silenced.
Performing root-cause analysis was the initial phase of the Electrical troubleshooting process, although it is described last. The knowledge you received from the troubleshooting procedure should be put to use in figuring out what might have caused the component to fail.