By Aku Laine
For a majority of commercial office buildings, an annual infrared testing program is the sole measure of electrical system reliability. Infrared testing does a great job of detecting overheating anomalies caused by conditions such as loose connections, overloaded circuits and unbalanced loads. Also, the thermographer or electrician conducting the infrared testing can identify visual deficiencies, such as discolored components, wiring issues and mismatched fuses, within the electrical enclosures.
The technology is proven, dependable and a staple of electrical maintenance. But what happens in an electrical enclosure after the data is recorded and the enclosure is shut? Often, the enclosure’s performance condition remains a mystery for an entire year until the next annual infrared test takes place.
As chief engineer of Brookfield Properties’ Newport Office Tower in Jersey City, N.J., my job is to keep the building’s hundreds of electrical enclosures operational.
Newport Office Tower is a 37-story commercial facility, measuring over a million square feet and housing a multitude of banks and financial brokers, often with their own on-site data centers and trading floors. A reliable supply of electricity is essential to their operations.
Although I have never faced a catastrophic electrical failure in my 20 plus years at the tower, like any experienced chief engineer, I know of incidents at facilities around the world where faulty electrical systems caused extended downtime, major repair and in the worst case, fire. For that reason, system reliability is foremost among my electrical maintenance priorities.
Example 1: Infrared image of hot spot in a main switch cabinet of bus duct system (Photo courtesy of Delta T Engineering, LLC)
In 2009, a situation arose that led to our improving upon the facility’s already high existing level of reliability, which consisted of annual infrared testing supplemented by periodic reliability examinations. It was during our infrared testing that we identified a hot spot in one of the main switchgear cabinets of our bus duct system. A root cause analysis showed that temperature fluctuations were causing parts of the bus duct joint to expand and contract. The resulting vibration loosened the bus duct joint bolts over time, allowing additional resistance, which caused the system to work harder. The bus joint was easily repaired after a utility shutdown that required hours of coordination among the utility company, the landlord and the building’s tenants. If the loose bus duct joint had not been detected, the result would have been catastrophic failure. Although the bus duct joint was repaired, the incident indicated that my electrical system warranted more frequent attention. Since infrared tests incur a relatively high expense, I turned my attention to potential alternative solutions. What I wanted was a way to constantly monitor every critical electrical enclosure in the building in a way that would complement our existing electrical maintenance program.
Wireless Temperature Monitoring
The answer arrived in the form of wireless temperature monitoring, a device created by Fred Baier, founder of Delta T Engineering, LLC. During his own career as a Level III certified infrared thermographer (Infraspection Institute), Baier had seen scores of incidents where consistent temperature monitoring would have vastly improved existing electrical maintenance programs. His experience led him to develop the Delta T AlertTM wireless temperature monitoring system, which consists of dual temperature sensors and dedicated software.
In addition to its primary function of identifying excessive heat rise conditions within electrical enclosures prior to failure, the system also offers energy savings by allowing for the timely repair of loose connections that create increased resistance, thus resulting in higher energy costs. The cost of cleaning and replacing electrical components is low compared to energy savings realized through this form of preventive maintenance.
Baier agreed to provide and install a sample wireless temperature monitoring system for our main switchgear application. The wireless dual sensor, which simultaneously monitors room ambient temperature and enclosure temperature, applies magnetically to an electrical enclosure cover. Installation requires only the drilling of a small NEMA IP20-approved hole, 15/32 inch. The device’s enclosure temperature sensor is inserted in the hole and its magnet keeps it in place. Once the sensor is installed, it is programmed via laptop with temperature thresholds determined by the enclosure’s size and how much it pulls in amperage. The programming software can accommodate nearly any application. Installation was completed in about five minutes.
Next, my office PC was loaded with the system’s software, which contained the preprogrammed information from the installed sensor. The sample system was now fully operational. It soon became apparent that the product worked well. From the convenience of my second-floor office, I could see at a glance the enclosure’s temperature and whether it was in alarm mode. Temperature trending graphs, repair logs and a host of valuable reports were just a click or two away.
I became convinced about the device’s usefulness and ordered 80 for periodic installation over the next two years. Baier completed the installation work and provided software training. The system can record up to eight readings per day at specific time intervals every day of the year.
Example 2: Catastrophic failure of electrical components, such as the sample burned breakers (top) and bus duct disconnect (below) can cause extended downtime and incur major repair expenses (Photo courtesy of Delta T Engineering, LLC)
The devices are currently installed on 36 floors. I see the temperatures and operating status for any application I choose, including main switchgear cabinets, current transformers, transformers, bus duct disconnects, variable frequency drives (VFDs) and motor control centers. Forty more devices are currently on order for use on additional bus duct disconnects.
Wireless Monitoring in Operation
The wireless temperature monitoring system has performed as expected, issuing warnings of “Critical,” which calls for immediate attention, and “Elevated,” which mandates close watching.
One alert, for example, identified temperature fluctuations in our 30th-floor electrical closet - panel labeled RP-30A. The wireless device monitoring this panel showed that the operating status varied among “OK,” “Elevated” and “Critical” on numerous occasions over a three-month period. Upon inspection, we discovered that the fluctuating temperatures were caused by different load conditions throughout the day. Although this three-pole, 200 amp breaker was not overloaded, infrared inspection showed a loose bus connection on phase “A” of the breaker as the cause of the alarm status. Once this breaker was repaired, temperatures reverted to within spec.
If the breaker temperature variations had gone unnoticed, phase “A” of this breaker would have burned up. In such a case, whatever’s on the other end of that power grid would go down and businesses would lose their power until it is repaired.
In another instance, we placed wireless temperature monitors on transformers controlling a new $3 million elevator modernization. The monitors showed that the transformers were running hot. Closer inspection with a multimeter revealed that the transformers were running at 110% capacity, rather than the specified less than 80% capacity. Six new transformers were installed to correct the problem and eliminate potential elevator downtime due to transformer failure.
Return on Investment
It is difficult to put a dollar figure on savings associated with wireless temperature monitoring. One readily available statistic based on insurance studies of actual electrical-related past losses is expressed as dollar savings per problem. By this standard, Newport Office Tower has saved approximately $65,000 through various wireless temperature monitoring-inspired repairs.
However, the true cost savings far exceed that figure. Dollar savings per problem does not take into account the cost of lost downtime and labor, which are usually the largest monetary components of an electrical failure. Loose cables, poor bus bar connections, corroded terminal connections, corroded fuse clips on disconnect switches and countless other conditions that give rise to temperature increases are all potential system stoppers. Repairing them prior to failure is the highest form of electrical system maintenance.
Aku Laine has served as Chief Engineer for Brookfield Properties in Jersey City, N.J. for over twenty years. He oversees the safe and reliable operation of building infrastructure, including all mechanical, electrical, plumbing and HVAC. www.deltatengineering.com