If intermittent problems go unnoticed or cannot be measured and investigated, small issues can become failures.
by Frederic Baudart

The Industrial Internet of Things (IIoT) has the capacity to reshape plant operations. The IIoT serves to connect the digital and physical worlds through the latest technology in order to improve the quality and speed of critical information. That information can be shared and used to make better-informed decisions.

Many factories use a preventive maintenance (PM) program to check critical equipment with portable tools to find signs of degradation. These essential methods for discovering system glitches often miss intermittent problems. If a maintenance technician does not capture critical information at the right time, intermittent unnoticed faults can escalate into complete failure. This is where the latest portable condition monitoring devices and software enter the picture.

Plants often deal with underperforming motors, and it is crucial to figure out the root cause of the motor’s failure. In this common scenario, technicians may discover the motor is running hot because of insufficient insulation in the windings. Narrowing down the reason can be difficult.

TechnicianImage 1. Maintenance technicians can place portable sensors on operational equipment to monitor for up to a month. (Images courtesy of Fluke Corporation)

The traditional solution to this problem relies on standard tools and research, logging and temperature readings. This hands-on method can produce incomplete data because it is difficult to isolate variables and correlate among current, voltage and temperature while operational conditions change. Overcompensation could happen if the maintenance team fails to isolate variables, which may lead to a temporary solution with an unfavorable outcome, like
replacing the deteriorated motor with an oversized motor. This approach trades one set of problems for another.

A newer approach uses smart technology that communicates between plants, equipment and employees. Wireless sensors that are networked to data systems create a trend of volt and current measurements over time. In the motor example, logging becomes unnecessary with portable condition monitoring because phase discrepancies can be remotely pinpointed as occurring at specific times during the equipment’s duty cycle.

Detecting Glitches

Some plants have at least one multimillion-dollar machine, also known as a tier one asset, that is powered by smaller equipment down the line. Often, these tier one machines are equipped with monitoring sensors by design, so plant managers can keep tabs on these machines’ performance.

A step down leads to second tier assets, which are often worth many thousands of dollars and are process-critical. These assets rarely have fixed sensors, so plant operators are often in the dark when it comes to raw data. For example, if a circuit is tripping intermittently and shorting a motor, and the conditions revert to normal by the time a technician arrives at the panel to troubleshoot, there is not much to do other than wait for the next circuit trip.

With portable condition monitoring sensors mounted on panels of this second tier equipment, managers and technicians can see intermittent faults as they happen or over time from their desktop, mobile phone or tablet. The equipment condition data allows “eyes” into what is going on with operating equipment, leading to better decision making on repairs, adjustments or replacement.

Portable condition monitoring sensors, for example, can simultaneously measure all three legs of three-phase power.

A technician can attach one current sensor to each phase or use the power monitor and then view the results on a smartphone. Since all three phases can be viewed simultaneously in real time, it is easy to quickly see differences between phases.

Fluke portable condition monitoringImage 2. A portable condition monitoring system

Setting a threshold on the sensor and the real-time alarms informs the technician of a sudden spike or drop in current to help quickly identify intermittent faults. The results help to identify overloads as well as degradation or failure of one or more phases before they cause a safety hazard or a breakdown.

Correlating Data

Before getting into the assessing measurement needs, the maintenance manager needs to set a baseline for comparison or control. This will set a uniform starting point for what good looks like and lead to trending, the visual process of collecting data on a routine basis to identify patterns and anticipate imminent machine failures.

After plant operators find fault indications, they can analyze, take action and approach the dilemma with a productive mindset. Temperature, current and voltage sensors, as well as associated cloud-based software, allow technicians to capture and monitor remote readings, all without disrupting operations.

When these versatile devices are mounted and connected to operational equipment or in electrical panels, collaborative maintenance managers and technicians can check circuit breakers in an electrical panel for overload, find three-phase power imbalances from harmonic distortion, or degradation or failure of one or more phases.

These sensors can capture changes in temperature within the panels to prevent failure in busbars, overload relays and other components. To dive deeper into motor health, positioning sensors can identify motor amperage spikes or overheating from bad bearings or insulation breakdowns.

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