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Volume 32, Issue 4

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Tuesday, 13 November 2018 16:18

Disaster Preparedness: Achieving Generator-UPS Harmony

Written by  ED SPEARS

Spears1Disaster can strike at any time. Events such as hurricanes or floods can leave businesses with outages and other power-related issues that carry significant risks. To be prepared for such an emergency, it’s essential for organizations to have a recovery plan and the necessary support to ensure they can return to productivity rapidly and safely.

According to the 2017 annual U.S. Blackout Tracker report, there were 3,526 outages in the country last year. The number of people affected by outages more than doubled in comparison to 2016 figures—an increase of almost 19 million. In total, the report found that blackouts affected nearly 27 million people last year, with an average duration of 81 minutes per power outage.

While power outages can undoubtedly be an inconvenience for the public, they can leave businesses with significant monetary losses. A recent ITIC study showed that for large enterprises with more than 1,000 employees, the costs associated with a single hour of downtime averages a loss of $100,000. In verticals like Spears2manufacturing, that number rises to $5 million for a power outage lasting just one hour. A few seconds of lost power may result in many hours of downtime while systems are reset and returned to service.

In the data center industry, power outages are becoming more common as organizations struggle with the complexities of hybrid IT – according to a recent Uptime Institute report. The survey showed that while an average data center is making better use of its energy today, it is more likely to suffer an outage. These outages are also more damaging than they were in the previous year.

As an ever-escalating list of threats leaves today's mission-critical environments more vulnerable to downtime, a growing number of organizations are bolstering their level of security by combining an uninterruptible power system (UPS) with a backup generator. In this article, we’ll explore how businesses can align these solutions and provide additional tips for enhanced protection.

Ensuring continuous uptime in a 24/7 environment

Although UPSs offer an excellent line of defense against dirty power, data loss, and equipment damage—as well as provide instant backup during short-term blackouts—they are not designed to deliver power indefinitely. Enter the standby generator, an ideal complement for applications that must remain online for extended periods of time without interruption.

Harmonization issues are inherent when interfacing a UPS and standby generator for optimal backup. Pairing the two devices is kind of like a blind date; compatibility is never guaranteed. To ensure businesses are forging a match—rather than an epic clashing of personalities—it is vital to understand the operational characteristics, possible load interaction and design of these devices.

Businesses can safeguard UPS generator system reliability and performance by taking into account the following considerations:

1. Assess the generator voltage and frequency regulation. Every UPS has a set input voltage and frequency window that if exceeded will cause the UPS to reject the generator as a source and go on battery. If a generator’s frequency or voltage ranges too widely or moves too quickly for the UPS to accept, then the UPS may interpret the generator as an unstable power source. If this occurs, the UPS remains on battery permanently, which will ultimately cause the battery to completely discharge and drop the critical load.

2. Size up the generator. Proper generator sizing is essential to ensuring the safety of both the UPS load and an organization’s personnel during a lengthy outage. Many companies expect the generator to accommodate air conditioning, emergency lighting, elevators, communications, and other vital services. If the generator isn't sized large enough, it won't be able to hold voltage and frequency within input tolerances when the UPS comes online.

The bigger the generator engine, the more stable the frequency, and therefore the more it can handle as the UPS comes off the battery, and begins to draw power from the generator. With that in mind, whenever budgets permit, it is wise to size up and also allow for some potential growth with the generator friendly UPS. Note that different generators, UPSs and regulator types preclude any vendor’s ability to “guarantee” a successful UPS-generator interface. So, the general recommendations for UPS models up to 25 kilowatts (kW) are as follows:

• 2-3 times the total load (including the UPS, A/C, and all other equipment that must remain online) for gasoline, propane, or natural gas-powered and mechanical governor generators.

• 1.25 to 1.5 times the total load for diesel-powered generators and those with an electronic governor.

3. Consider the fuel source. The most common generator fuel options include propane, natural gas, and diesel, each of which comes with its own set of advantages and disadvantages. Natural gas and propane operating generators can be slower to respond and may need to be sized larger than their diesel counterparts. Diesel is widely considered the best fuel for UPS applications and is predominant for generator solutions 50 kW and larger; however, it has a short storage life, and its cost and special storage requirements can strain budgets.

4. Don’t overlook the governor. Most generators are equipped with a governor, which limits the speed of fuel being delivered to the engine to a safe level and stabilizes the voltage, frequency, and slew rate of the generator output amid load changes. Electronic governors are quick to respond, while mechanical governors are typically slower and can also cause calibration challenges.

5. Consider the UPS topology. The type of UPS will also impact UPS generator compatibility and configuration, as not all can compensate for frequency variations without relying on the battery. Both standby and line-interactive UPSs use battery power to prevent frequency variations from affecting the protected load. So, a generator's unstable frequency may cause the type of UPS to transition to and from the battery frequently while the generator is running. A double-conversion, online UPS, on the other hand, has a wider acceptable window for input voltage and frequency. It recreates the sine wave and filters frequency variations as part of its normal operation, thereby preserving battery life. Because it continually rectifies AC to DC and then inverts the DC back to AC, the online UPS produces an output that corrects for incoming voltage and frequency deviations. For this reason, double-conversion technology is the most common for critical load applications, and the most advantageous type of system for generator integration.

6. Consult with the manufacturers. Often you can avoid a range of potential problems and the UPS not working on generator power by first ensuring that the generator manufacturer has tested and approved the product's intended use with UPSs. To ensure that optimal UPS vs. generator sizing is achieved, it is wise to consult with both the UPS and the generator manufacturer before finalizing a purchase. Also, the capacities of prospective loads to be protected can generally be found in the manufacturer's specifications.

Although UPSs, generators, and other power-management devices are typically reliable, they do require ongoing monitoring and support. That’s where power and virtualization management software can come in handy for IT operators.

Keeping a watchful eye

Spears3Innovative software solutions have emerged as an essential tool for helping businesses continuously monitor and diagnose the state of their electric grid, batteries, and power sources, together with the condition of the UPS's internal electronics.

Most businesses today are also leveraging some level of virtualization, whether it is an application, storage, network, or server virtualization. Outlined below are two of the top criteria for businesses and their IT teams to consider when choosing software that can safeguard equipment and expand the capabilities of the virtual environment.

1. Establish capabilities for power management software to integrate with any in-use virtualization platforms and other devices that support a network interface (power management devices, environmental sensors, PDUs, and more).

2. Identify objectives for the power management software. A helpful question to ask includes the following:

• Do you want it to plug directly into your virtual dashboard?

• Do you want to initiate planned migrations of data and computing capacity?

• Do you want to perform automatic load shedding during a power outage?

• Do you want the ability to remotely shut down a host in a cluster without needing to install shutdown agents on each host or each virtual machine?

Once a business deploys a power management software solution that integrates with their virtualization platform and meets their environmental needs, they will be able to enjoy many benefits. In addition to helping monitor critical power protection devices, and ensure uptime in the case of a power event, power management software allows organizations to be more efficient with their hardware, power, cooling, and management. The systems also allow organizations to leverage new features and functionality to extend battery runtimes and minimize generator load.

A vision for the future

As monitoring and management solutions continue to evolve, advanced services like predictive analytics can help IT managers anticipate the failure of critical power components before they occur – ensuring their system is always up to the task in the case of an event. By collecting and analyzing data from connected power infrastructure devices, these solutions provide IT administrators with the insight needed to make recommendations and act quickly to prevent unnecessary headaches.

Computer-based monitors will get continue to better and better about making decisions on their own as predictive systems advance, and more data is collected. In context with the advancement of Internet of Things (IoT), Big Data and machine learning, predictive analytics will continue shifting the power management model from reactive to proactive.

A lot rides on an organization’s power system and infrastructure. Unplanned power outages can have a devastating impact on a business – posing the risk of missed SLAs, lost productivity, financial penalties, brand damage, and lost customers. To optimize power infrastructure and avoid the dangers of downtime, organizations and their IT teams need to be prepared with a strategic set of solutions that allow them to be prepared and respond quickly in the case of an event.

There are a host of new technologies and solutions that provide IT staff with the capabilities needed to ensure uptime and improve power management. By strategically aligning standby generators with UPSs, coupled with power-monitoring software for ongoing support, IT managers can gain better control over their entire power infrastructure. With a marriage of solutions that are integrated and built to work together, organizations will ensure they have a system that is built to last.


Spears EdEd Spears is a technical marketing manager in Eaton’s Critical Power Solutions Division in Raleigh, NC. A 37-year veteran of the power-systems industry, Spears has experience in UPS-systems testing, sales, applications engineering, and training — as well as working in power-quality engineering and marketing for telecommunications, data centers, cable television, and broadband public networks.