Providing Non-Stop Power for Critical Electrical Loads

The loss of electric power interrupts some vital digital communications networks, advanced medical therapies, financial transactions such as credit cards and bank operations, elevator service, refrigeration and other essential services. This equipment is so critical that there is a great demand for non-stop electric power. There are many ways to provide auxiliary power for times when the public supply goes down. We may think first of backup generators, but there are other devices available, including flywheel generators and battery/inverter systems. Choosing among them is the subject of this discussion.

The Transition, a Critical Time

Failure of the public electric feeder is usually unexpected. Whatever means have been chosen for providing alternate power will ordinarily have to function without advance warning. Since critical loads may be very intolerant of even the briefest interruptions in power flow, this is the most critical time.

Reciprocating engine driven generators are one of the most common sources of alternate power during blackout periods. Unfortunately, there is an unavoidable delay to start the engine, allow it to get up to speed, and then to complete the functions necessary to allow it to assume the load. The loss of power for only a few cycles (1/60th of 1 second = 1 cycle) is enough to reset most digital processor equipment.

Bridging the Time Gap

There is a need, therefore, to maintain a smooth supply of electricity to vital loads so there is an effective transition to an alternate supply. This can be done with a device called an uninterruptible power supply (UPS). Originally designed for digital computers, these devices employ a battery as a power reservoir. There are different types of UPS devices available on the market and these differ in the way that the electric energy stored in the battery is connected to its load.

Combining UPS with Generator Sets

In order to best maintain the operation of vital equipment through an interruption of normal supply, a UPS system can be combined with a generator set. The UPS equipment provides the critical time necessary for an orderly start of the generator set. The full article discusses the type of UPS system that is best used in this arrangement.

Planning for Equipment Failure

The design of a backup, or emergency, power supply capability should reflect how critical the loads are to be supplied. Redundancy should be in proportion to the level of risk. When truly critical electrical needs are at stake, additional reliability measures should be taken. Read more about contingency planning in the full article.

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