Wednesday, May 1, 2019

Is A Wireless Temperature Monitoring System Feasible For Critical Electrical Asset Reliability?

Recently, the data center where you function as the Chief Financial Officer (CFO) experienced a rapid expansion with the on boarding of a national banking chain that has just bought out several smaller banking corporations.  The footprint of the data center nearly doubled in size to support this new business.  Six months after the expansion, there was a catastrophic failure of the main power supply in the new portion of the building.   Auxiliary power was available, but it too had to undergo some modifications in order to adequately provide the amount of power needed for normal banking operations.  This one-two punch resulted in a 12 hour interruption of services to the banking chain.  Obviously, the data center’s C-Suite had to overcome severe damage to its reputation, so they immediately hired an engineering consulting firm to help them prevent this occurrence from repeating in the future.

The consulting firm recommended that the data center add a temperature surveillance system to their existing condition based maintenance program because of the criticality of the services the data center provides to its customers. The consulting engineer and the data center’s reliability team examined the entire electrical infrastructure and identified what components were most critical to normal operations and what components had the highest possibility of failure and where the early warning signs of the mode of failure would be detectable with temperature sensors.

                                                                                                                 Wireless Temperature Monitoring

There are several temperature monitoring systems commercially available:

• Hard Wired Single Point Measurement – this system requires a data hub to collect data, a power supply, communication source such as the internet and one hard wire connection to each potential point of equipment failure that requires monitoring. In a single piece of switchgear, there could easily be 12-20 individual points of failure to monitor making this difficult and expensive to implement.
• Hard Wired Infrared Camera and Sensors – this system also requires a data hub to collect data, a power supply and a communication source to transmit the data. The limitation of this system for the data center was the Field of View of the IR camera.  The IR camera can only measure what it “sees” and it is often difficult to mount cameras in compact equipment in a location that will see the targets.

• Wireless Temperature Systems – this system is based on the fact that failing electrical connections produce heat and the internal temperature of the panel where this connection is located will rise. This rise in temperature inside the enclosure can be compared to the outside ambient temperature and the resulting difference (ΔT) between the two temperatures can be used as an alarm to the maintenance team. An example of this type of system is the Delta T Alert System. This system requires one wireless sensor per enclosure (not per target), power from either batteries or hard-wired source and wireless communication gateways utilizing Z-Wave technology.  Z-Wave technology allows communications from device to device using low energy radio waves and is proven technology around the world for many home automation applications (burglar detectors, smoke detectors, etc.).  The Delta T Alert System has four sensors:  ambient temperature sensor, enclosure temperature sensor, a humidity sensor and, with the powered sensor, a contact thermocouple sensor.  Using the Delta T Alert Software, the maintenance team can configure and program the sensors and determine the appropriate alarm limits required for their specific application.  Data trending analysis provides a historical record of temperatures for each sensor enabling the maintenance team to proactively monitor the health of the targets.

The System of Choice

The data center’s management team researched the different types of temperature monitoring systems and determined that a wireless temperature system for both the main and auxiliary power systems was the best choice.  Because the data center has many electrical targets to monitor, the management team decided against the Hard Wired Single Point Measurement system due to complexity and expense.  Likewise, due to the many electrical targets to monitor, the management team decided against the Hard Wired Infrared Camera and Sensors due to the exorbitant expense of the many IR cameras and sensors that would have had to be installed.

The wireless Delta T Alert System was installed in the data center and the maintenance team trained on how to select the appropriate alarm settings for their application.  With constant temperature monitoring, the data center’s C-Suite is now confident that they will not encounter a future power outage due to power equipment overheating.

 Conclusion:

Cost-efficient wireless temperature monitoring is commercially viable since it does not require as much hardware or cabling that other systems require.  Continuous monitoring of critical electrical assets enhances an existing condition based maintenance program and alerts the maintenance team when temperature data is outside of pre-determined limits.