Basic Emergency Power Systems

Related Courses

Key Questions

The following key questions are answered in this module:

What is the purpose of an automatic transfer switch (ATS)?
The ATS is an electro-mechanical device which has power connected to its separate, isolated inputs from both the electric utility and the standby generator. The ATS output is connected to the "load" side of the building electrical supply.

What are the two major categories of widely used standby power systems?
The two major categories of widely used standby power systems are generators and uninterruptible power sources (UPS).

What are the basic items that should be checked before starting a generator?
The basic items that should be checked before starting a generator include the engine oil level, the coolant level, the battery fill level, the fuel system (for leaks) and the exhaust system (for breaks or leaks).

What is the functionality of an engine block heater?
Almost all generator engines are designed to use what is known as "block heaters", which must be connected, and kept operational all the time, especially when the generator is in a stand-by mode (not running). Block heaters are powered by normal line power.

What are the ATS steps of manually switching from the utility-supplied power to generated power?
The ATS steps of manually switching from the utility-supplied power to generated power include verifying utility power is interrupted, starting the generator, changing the transfer switch from utility feed to generator feed, and verifying power is now going to load.

Sample Video Transcript

Below is a transcript of the video sample provided for this module:

There are really two major categories of widely used standby power systems; generators and UPS. I’m only addressing generators in this course. So, what’s a generator? The generators in this course is talking about are a type of rotating machine, which, by design, generate electricity when rotated at a certain speed by some type of motor or engine. The generator portion of this system is generally a very robust, reliable device, which, when operating, puts out up to a specified amount of current at a voltage consistent with the voltage of the system it is feeding. Today, the electronic regulating devices built into most generators, allow it to put out electricity in a form which is indistinguishable from the normal, utility-supplied power. Having this power-conditioning included in the generator is especially important when feeding sensitive electronics and most small motors, during a utility outage. Most generators are rotated, or spun, by internal combustion engines. These engines can be designed to use one (sometimes two; also known as “dual fuel”) of several different types of fuels, such as: gasoline, diesel fuel, natural gas, or propane. However, the most common generator fuel is diesel fuel. This is due to the fact that diesel fuel is readily available, easily stored and not easily ignited. The internal combustion engines used in generators are very similar to the engines used in your car or truck, with just a couple of modifications. Those modifications allow the generator engine to start-up very quickly and to run at a fixed speed for many hours, or days, without undue wear and tear on the engine. Like most internal combustion engines, generator engines are normally started by using a lead-acid storage battery. Almost all generator engines are designed to use what is known as “block heaters”, which must be connected, and kept operational all the time, especially when the generator is in a stand-by mode (not running). Block heaters are powered by normal line power. If the block heater doesn’t run all the time, there is a good possibility, particularly in colder climates, that the engine lifespan would be shortened considerably, as it must come up to full RPM’s as soon as it is started. Your typical automobile engine wouldn’t last long if, when started cold, it was revved up to a high RPM right away, and this procedure was repeated every few days. To prolong the engine life in a generator, the block heater is used to keep the engine coolant warm, but, even more important, this keeps the engine lubricating oil at a free-flowing temperature, allowing it to circulate properly as soon as the engine is started, thereby facilitating quicker starting of the engine and maximizing engine life.