September 6, 2016 | by guest blogger Greg Stark, PE, Assistant Professor of Practice, Biological & Agricultural Engineering Department, Texas A&M University
The costs of power quality disturbances to electronic equipment can be very large. In many facilities the costs can include damaged equipment that must be replaced, loss of building comfort and efficiency leading to complaints by users and, in the worst cases, a loss of tenants or frequent equipment downtime (because equipment doesn't operate correctly or repeatedly reboots for no apparent reason). There is really no standard methodology or equation published that helps people quantify their overall costs from power quality. Most facilities managers have a feel for the costs of downtime for various devices in their buildings on an hourly basis and know what equipment replacement and installation costs are when a device fails and must be replaced. The part that most people may not have a good feel for, and don’t mention, is reduced equipment life when the equipment doesn’t fail catastrophically but simply doesn’t work right and power quality isn’t the first thought. Lots of resources can be expended searching for equipment problems that don’t exist when power quality is the problem.
Power quality problems affect electronic equipment in many different ways depending on the type of power quality disturbance, the duration and the sensitivity of the equipment. Certain power quality disturbances like transient spikes can significantly reduce the life or result in catastrophic damage to electronic devices. One of the more common problems users of electronic equipment deal with these days is electronic equipment resets and reboots caused by power quality disturbances. When electronic control devices reset/reboot they can cause significant disruptions to building operating equipment or manufacturing processes. The results can be building systems such as lighting, HVAC or security systems that don’t function as they are supposed to leading to frustrations for both building operations and management.
In cases where the electronic equipment did not reset/reboot, the equipment could be sending bad data signals or generating data communication error messages that are hard to recreate to troubleshoot. By the time building operators can communicate the issue to maintenance, the power quality disturbance is gone and the problem cannot be recreated with the equipment. This leads to frustration between the users of the equipment and the people who maintain it where neither thinks the other knows what they are doing. If the issue is ongoing, it can lead to general thoughts by building users that building operations and maintenance doesn’t know what they are doing or doesn’t care.
It is still common for operations and maintenance employees to blame the utility for supplying “dirty power” when equipment problems occur in buildings. As the cost of power quality monitoring equipment has come down and more devices are available targeted to building operators it is becoming increasingly easy to monitor power quality in buildings. Having accurate power quality disturbance data can be invaluable in determining which disturbances in a building are causing problems, correlate the timing of the problems with electrical power supplier operations and events on their systems to rule them in or out as sources, or even rule power quality out as the cause of specific building equipment issues. Many power quality problems today are created on-site in the customer’s facility. Relying on the utility to measure and report electrical disturbances at their point of power supply typically doesn’t provide any useful information regarding what the internal power quality issues are or where they are coming from within the facility. In addition, power quality monitoring can provide historical baseline numbers for the future to compare the number and types of current electrical disturbances to previous numbers to determine if issues are getting better or worse.
It is important to remember that in order to select a power quality mitigation solution that works with a good cost/benefit ratio, the type of power quality disturbance must first be known. Many building owners have mistakenly purchased expensive power quality solutions based on what other buildings problems were; only to find they have a different type of power quality disturbance and the installed “solution” is useless for their type of disturbance. By monitoring power quality on-site, accurate information related to the types, magnitudes and numbers of disturbances present in the electrical system can help determine the best solutions to equipment problems and help in writing equipment selection criteria for any new piece of electrical equipment purchased and installed in the building. This can ensure the new equipment can function within the existing environment and its installation will not create new power quality disturbances that cause existing equipment to have operational issues.
The benefits of understanding and monitoring power quality parameters in facilities include:
- Having accurate operating data to document which electrical disturbance(s) (if any) occurred at the time of equipment malfunction or failure in the building.
- Having accurate operating data to determine which electrical disturbances are benign and which are problematic so successful solutions can be found with good cost/benefit characteristics instead of the trial and error approach of various power quality solutions.
- Determining which electrical devices in the facility may be starting to wear and degrade towards failure when they start producing power quality disturbances they shouldn’t normally produce. It is not uncommon for failing equipment to produce power quality disturbances for some time before it actually fails.
- Provide a baseline of the typical measurable power quality disturbances and the relative health of the electrical environment in the building for consideration in purchase of new equipment.
Many building owners are now writing power quality requirements into their purchase specifications so any new equipment going into their building is a known quantity regarding how sensitive it is to power quality disturbances. If the new equipment can’t meet the building owner’s criteria, the equipment can’t be installed or must be installed from day one with a power quality mitigation solution in front of it.