Part 1: UPS: Paving the Way for Power
Part 2: Understanding Types of UPS
Part 3: UPS Maintenance Strategies
UPS Maintenance Strategies
By James Piper, P.E. - October 2012 - Power & Communication
A UPS maintenance program targets two major components: batteries and the system itself. Each one is critical to the reliability and long-term performance of the UPS. The type of batteries installed and their capacity will dictate the type of maintenance tasks technicians perform and the tasks' frequency.
For example, smaller passive-standby systems generally use sealed batteries that require little maintenance. Double-conversion systems typically use flooded-cell batteries that require monthly maintenance. But even though they require more maintenance and are more expensive to replace, flooded-cell batteries offer nearly three times longer performance life than sealed batteries.
Typically, flooded-cell batteries are installed in banks and isolated rooms. In terms of their maintenance, technicians should:
- inspect and test the room's ventilation system at least monthly to ensure its proper operation
- inspect batteries for proper electrolyte levels and signs of leaks
- inspect terminals for signs of corrosion and accumulation of dirt, as well as measure and record the voltage and current of the entire bank.
- record the voltage for a random number of individual cells and test their electrolytes
- record measurements in a log to track battery performance.
Twice a year, technicians also should inspect and re-torque battery connections. Loose connections lead to a buildup of heat at the battery terminals, decreasing system capacity, reducing battery life, and creating potential fire hazards.
Annually, they should load-test the battery bank to determine its capacity. This process requires disconnecting the UPS from its power source and allowing the batteries to supply power to a connected load. The test continues until the system design reaches its run time or until the system shuts down because of low battery voltage. Technicians should conduct thermal scans during the test to identify loose or corroded connections.
The UPS itself also requires regular maintenance. At least annually, technicians should take the system offline and inspect its components for signs of corrosion and heat damage. A thermal imaging system will help identify loose connections and components that can overheat.
Finally, they should remove dirt and dust from UPS components, particularly if the accumulations would interfere with heat transfer. Technicians also should re-torque power connections per the manufacturer's specifications.
James Piper is a national facilities management consultant based in Bowie, Md. He has more than 25 years of experience with facilities maintenance and management issues.