Carolina Power & Light Company

Its 10 o’clock in the evening and a thunderstorm is passing through your area. At home, you aren’t worried because you know that your facility has a UPS and a backup generator system. You decide to call facility maintenance, and you discover that the UPS took over for the loss of power, but the generator did not start. It tries to start, but after a few seconds, it shuts down. What is wrong here?

At that moment, many things are going through your mind. When was the last time you serviced the generator or the UPS? Did you test the generator under load? When did you test it?

This situation is very normal for a facility who buys a UPS and a generator and has not correctly analyzed what the emergency power (EP) plan should be. It is crucial that you understand that when considering emergency power there are six main questions you must ask yourself.

What is the critical load that we want to protect?

When do we want to protect the load?

All the time, some of the time, under certain conditions, and for how long?

Where do we place this emergency system so that it meets all codes? Do we have to be

concerned about location, physical size?

Why do we need to provide emergency power backup?

How much can we spend to get what we want?

Remember it is as important to know that you have the correct emergency power protection, as it is to actually have the protection. Let’s answer these simple questions and assure ourselves that a 10pm phone call will be worry-free.

(1) Who will be responsible for maintaining the emergency power (EP) system?

Having an assigned person to maintain and manage the EP system helps assure that a total plan is in place that outlines all the necessities of the operation of the EP system. Items such as: the system’s size, how large is the generator, how is it installed, are you using an isolated neutral Automatic Transfer Switch (ATS) or not, must be understood by a key person to assure that total protection is obtained?

(2) What is the critical load that we want to protect?

There are times when only a portion of the plant requires protection. This can and often requires extra work, because that portion may have to be physically segmented away from the total facility’s power distribution network, yet must continue to be powered by the utility during normal service. You must also consider planned load additions.

When do we want to protect the load? All the time, some of the time, under certain conditions, and for how long?

Utility power is relatively constant. The interruptions that can occur to an electrical line can consist of: momentary outages, voltage sags, voltage transients, and power losses. The type of EP protection will depend on how many of these interruptions one wants to minimize. For example, if only electrical dropouts are a problem, then maybe only a generator is necessary. If only momentaries are the concern, then a UPS or some other ride through system is the best solution. A key item to remember is that it is important to design the EP system to fit the load requiring protection. Overdesign can result in over budget costs and operational problems.

(4) Where do we place this emergency system so that it meets all codes. Do we have to be

concerned about location, physical size?

This part can be the hardest to determine. It is important to install the EP system so that the generator noise output does not disrupt the outside residents. There is also a concern for the storage of the fuel for the EP system. However if the fuel is Natural gas, then it is critical that the source of the gas is easily available. A concern that does not receive sufficient attention is maintenance. Having a maintenance plan in place is necessary, but not being able to service the system because of its location can lead to incorrect servicing techniques being used. Will there be too many bushes surrounding the EP system to prevent easy access? The best place, yet the most problematic is to place the generator portion of the EP system as close to the main distribution room as possible. Provide sufficient clearance around the generator for maintenance, and assure that there is easy access to the fueling location.

(5) Why do we need to provide emergency power backup?

This question can only be answered by asking another question. How much pain can your facility (Data Center, manufacturing machines, etc.) tolerate? Can your data center handle power interruptions of several cycles long? Several seconds? What happens to your extrusion line when a momentary voltage drop occurs during a lightning storm? Do you lose 1 hour of production or an entire day. Can you afford to lose power for a day? Does your Utility have a shed-load program that can save you money on installing a generator EP system?

(6) How much can we spend to get what I want?

It is important to understand that EP systems have two expenses. The first is the actual cost of the EP system, including hardware and installation. The second cost is the maintenance, service, and fuel. An EP system will require periodic cleaning and adjustment once a year. The cost of maintenance also includes having an onsite person knowledgeable in the technical aspects of the EP system to assure that maintenance is kept up. He or she will be responsible for assuring that periodic testing of the EP system occurs during the year. Understanding total cost of ownership is crucial to budgeting for purchase.