A robust predictive maintenance plan is essential to the longevity of your electric motors. Regular inspections and testing can identify potential issues before they become a problem, leading to unexpected downtime. As part of our commitment to keep you up and running, the Hi-Speed team relies on a variety of specialized tests, such as non-destructive ultrasound testing, to monitor and diagnose the motor’s internal components, and much more.
How Does Ultrasound Testing Work?
This inspection features a handheld testing unit that sends a high-frequency signal through the part or assembly being inspected. As these sound waves pass through the metal, they will be reflected with the same level of energy and frequency, unless an anomaly exists.
The technician then listens for specific sound signatures associated with different types of known faults. For example, erratic sound bursts would indicate internal arcing, while a hissing noise typically indicates a failing bearing. Ultrasound testing is not recommended as a DIY project. It takes the skills of an experienced technician, like those at Hi-Speed, to properly perform and unlock the benefits of ultrasonic testing for your business.
Types of Ultrasound Testing
There are two types of ultrasound tests that can be used to keep your electric motors running at peak performance. The pulse-echo option uses a singular probe to send and receive through the part. The time it takes for the signal to return can determine the location and depth of defects such as cracks, voids, or internal corrosion levels.
The second option is called the trough transmission or attenuation test, which uses a transmitter and a separate receiver. An increase in sound energy typically indicates degrading wire insulation or an internal void. A decrease in the sound energy could indicate a motor winding deficiency or a reduction in material density from overheating.
What Potential Issues Can Ultrasound Detect?
When it comes to electric motors, ultrasound is the preferred method for detecting potential electrical and mechanical issues during operational cycles. These electrical issues can include:
Corona – is caused is the ionization of air around a connection point or terminal. Because there is no significant heat signature, this condition cannot be detected with infrared cameras.
Tracking – occurs when a low-current pathway to ground forms across the insulating material. This is typically caused by loose connections or excessive contamination.
Arcing – is the result of more severe (higher) discharges across an insulator, which can result in significant motor damage if left unchecked.
Wiring insulation – over time, the insulation can begin to break down due to the heat generated during operation. Cracks or damaged insulation can result in voltage loss, affecting the motor’s performance and reliability.
Partial discharges – can occur inside the electrical panels or switch gear used to power your electric motor. These voltage spikes are especially detrimental to the motor’s longevity and efficiency.
Mechanical issues can include:
Looseness and Misalignment – ultrasound testing can identify loose components and connections that reduce operational efficiency. Misaligned shafts or other attached devices can increase friction and excessive heat being generated.
Lubrication issues – low oil or grease levels can cause premature wearing and unexpected failure of internal components, bearings, and seals.
Bearing failure – is one of the most common preventable issues that can be quickly diagnosed using ultrasound testing.
Soft footing – an uneven mounting location puts additional stress on the motor and any attached components.
Leak detection – whether you’re working with air, steam, or fluids, ultrasound can detect the location and direction of the leak by analyzing the intensity of the sound waves.
Additionally, ultrasound testing, with its minimal downtime, can be used to verify the proper operation of system valves and check corrosion levels within pipes or conduits.
Benefits of Ultrasound Testing
Ultrasound testing can be used for several different types of electrical equipment during operation to avoid the shutdowns required by other testing options. Technicians can work from a distance safely to reduce exposure to potential hazards, such as moving components or excessive heat buildup.
Ultrasound testing can identify potential issues, allowing for proactive management before a failure occurs. Eliminating unexpected downtime reduces operational costs and capital expenditures by preventing major breakdowns. However, ultrasound testing is not recommended for very small, thin, or irregularly shaped parts that are non-homogeneous. The metal surface should be cleaned to remove any loose paint or scaling before conducting an ultrasound test.
Hi-Speed recommends ultrasound testing as part of a more robust predictive (or preventive) inspection and maintenance plan for our customers. To learn more about the benefits of ultrasound testing, or to schedule a test for your facility, please call us at 1-800-713-0103 or email us, and one of our electric motor experts will be happy to answer all your ultrasound testing questions.
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