Continuously Monitoring Critical Electrical Assets

Emerson's Jonathan Murray


One common thread with Industrial Internet of Things (IIoT)-based sensors is that they typically will replace periodic, manual measurements. We shared IIoT application examples in past posts of how business performance—in safety, reliability and efficiency—can be improved. The common thread is that continuous data streams from these IIoT sensors feed analytics applications, which can help spot & notify personnel of emerging problems. This allows time for remedial actions to be taken before performance is affected.

In a new whitepaper, 3 Steps to Monitor Critical Electrical Assets, Emerson’s Jonathan Murray shares examples of how electrical power plants can perform continuous condition-based monitoring on their important assets.

Jonathan describes the three steps to move from manual time-based and reactive maintenance to proactive and ultimately predictive maintenance:

  1. Prioritize which assets should be monitored.
  2. Apply continuous condition-based monitoring.
  3. Analyze data and evaluate asset health.

He shares an example highlighting the cost of an outage condition. The average price of electricity sold given a 60% industrial / 40% commercial mix is $30 per megawatt-hour per a November 2016 U.S. Energy Information Administration report. For a 500 MW generator, this means each hour of downtime costs $15,000 in lost potential revenue. One-week of downtime means over $1.2 million in potentially lost revenue.

It’s important to start with an assessment of electrical power delivery system assets including:

…generators, generator circuit breakers (GCBs), line disconnect switches, step-up and step-down transformers, segregated and non-segregated bus ducts, potential transformer cabinets, medium voltage switchgear, motors, and other equipment needed to support the transmission and distribution of power.

Jonathan recommends a cross-functional team be assembled to perform the assessment and begin with a:

…system level rather than an equipment level to ensure you are not overwhelming the stakeholders during the decision-making process. Questions should cover each area of interest and calculations should be made to rank the effect of a system failure on the power plant. The systems with the greatest impact will be the highest priority.

Next, take the:

…highest priority equipment and employ a Failure Mode, Effects, and Criticality Assessment (FMECA) to help identify where and how the equipment might fail. The FMECA is an in-depth evaluation and takes significant time to complete, so it should not be used on every asset; many companies look at the top 10 percent of their most critical assets.

Once prioritized, step 2 is to identify common electrical asset failure modes. These include thermal breakdown, insulation breakdown, and air dielectric breakdown. Typical direct contact temperature measurement sensors such as thermocouples and RTDs don’t work well in medium voltage switchgear thermal measurement application due to air gap distances required by IEEE standard C37.20.3. Instead, wireless passive sensor systems:

…provide real-time continuous monitoring via direct connection to critical measurement points… These sensors employ surface acoustic wave (SAW) technology…

Request and download the whitepaper for more on continuous partial discharge (PD) and humidity monitoring as well as typical monitoring system architectures and analysis methods used.

You can also connect and interact with other power generation industry and IIoT experts in the Power and Wireless groups in the Emerson Exchange 365 community.

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