Restoring power to data centers can result in costly maintence and downtime for service providers. In 2016, the national average cost of downtime was almost $9000 per minute. Often, this power failure can be attributed to preventable hardware failures. In 2016, the Ponemon Institute conducted a study to quantify the cost of downtime and identify the most common causes of data center outages. According to the study, the most common reasons for unplanned outages are UPS system failure, cybercrime, accidental human error, water or heat failure, weather-related disasters, generator failure, and IT equipment failure. The least common reason for unplanned outages was IT equipment failure, coming at 4%. However, when the study examined the total cost of each cause of failure, IT equipment failure ranked the most expensive. Hardware failures can stem from many places, including cooling fans, hard disk drives, and busbars.
An integrated cloud technology company noticed that the backup servers in its data centers were being used more than normal. After a little digging, the team realized that their primary servers were experiencing power failures, which caused the system to rely on the backup servers. Upon inspection, they discovered that the busbar and crown clip connection for the primary server had corrosion buildup. This buildup was attributed to fretting corrosion, or micro-motions that wear contacts and expose fresh layers of metal to oxidation. This eventually created an open connection and, ultimately, power failure. The provider determined that the micromotion occurred during both shipping and regular operation. The data center provider needed a solution that would protect future manufactured connectors from fretting corrosion and restore reliable connectivity to damaged connectors in the field.
Sometimes, unplugging and replugging connectors is enough to solve intermittent power failures. However, unless a dielectric lubricant is applied to the connector, the connector will continue to oxidize and corrode. Grease is often selected to combat fretting corrosion. The grease seals the contact surface, which prevents oxidative wear particles from forming. With the grease protecting any freshly exposed metal, oxidation is inhibited, open connections are avoided, and continuity remains constant.
Because the company’s manufacturing partner was aware of the benefits of lubrication, they recommended Nye Lubricants. For connector applications, Nye often recommends NyoGel® 760G, a silica-thickened, medium-viscosity, synthetic hydrocarbon grease. This dielectric grease has had proven success in the automotive industry, where it has specified by OEMs for 50 years to combat fretting corrosion caused by on-road conditions and is considered the industry standard. But would it work for busbar connections? Nye’s application and test design engineers decided to validate NyoGel® 760G for use in busbar applications by using a multi-terminal fretting test apparatus.
The fretting wear test apparatus, designed by Nye engineers, is made up of two electrically isolated testing stages that can have various components affixed to them. For this provider, Nye engineers modified the apparatus with custom busbar fixtures to replicate the conditions of the customer’s application. The busbars were mounted to the motion side of the test rig, and the corresponding crown clips were mounted to the stationary stage. A four-wire resistance measurement was taken across each testing specimen. A predetermined stroke length (amplitude) and frequency were applied to the motion side of the test rig via voice coil linear actuator. Using laser interferometers and an absolute encoder, motion can be monitored and controlled down to 1 micrometer.
As the test runs, fretting wear occurs between the test connectors, forming wear debris and allowing oxidation to occur. This oxidation causes a rise in the resistance between the connectors, ultimately rising until a point of failure, determined by the Nye engineers and customer. The use of a lubricant inhibits the oxidation process and also minimizes the wear debris, which greatly extends the life of the connector pairs by keeping resistance levels constant. Resistance values are monitored in real time and flagged when failure occurs.
Nye engineers ran two tests using the apparatus: one on unlubricated contacts and one with contacts lubricated with NyoGel® 760G. NyoGel® 760G was run for over 1 million cycles without any failures; it was manually stopped in the interest of time. These results were compared to approximately 75,000 thousand cycles for the unlubricated contacts before failures were noted. After further internal testing, the customer decided to use NyoGel® 760G for their tin-plated connectors, which is now being used in their data center equipment across the world. 760G has successfully restored equipment power reliability to servers that experienced power failures, reduced unplanned downtime for the company, and ultimately saved them thousands of dollars.