Generator Sizing Guide

BECAUSE WITH A GENERATOR, size MATTERS
The first thing you need to do is determine what size generator would work best for your particular requirements.

This section will help walk you through that process.

When purchasing a generator, it's important that you select one that's capable of meeting your energy requirements.

• You must match the rated output of the generator to the maximum anticipated power to be used.

This section will assist you in estimating the power requirements so you can purchase the generator that will satisfy your needs.

• This includes using the accompanying worksheet to make a list of the tools and appliances you expect to operate, as well as the approximate power requirements for each device.

Once you have the list, you can estimate the highest demand that will be put on the generator under the "worst-case" conditions. With this figure, you can determine the appropriate model Yamaha generator for your particular needs.

WARNING: Electrocution, severe personal injury or death can occur: Do not connect any generator to any building's electrical system unless an isolation switch has been installed by a licensed electrician. Refer to the Generator Owner's Manual.

CAUTION: Property damage can occur: Do not connect any generator to any building's electrical system unless an isolation switch has been installed by a licensed electrician. Refer to the Generator Owner's Manual.

TAKE IT STEP-BY-STEP
Follow these steps when determining your energy needs:

1. Identify the wattage requirements for the tools and appliances that you want to power. The power requirement for the tool or appliance can be found on its identification plate or in the Owner's Manual. If the power requirement is given in amps, multiply the amps times volts to derive the required watts.

Amps x Volts = Watts

2. Add up the required watts of all the tools and appliances you expect to operate simultaneously.

3. The total watts derived in step 2 is the size Yamaha generator you need. These three simple steps will "size" a generator.

The Additional Guidelines section explains the procedures to calculate and size for motor starting.

ADDITIONAL GUIDELINES

CONVERTING AMPS OR HORSEPOWER INTO WATTS
If necessary, use these formulas:

Watts = Amps x Volts

Running Watts* = Horsepower x 932** (for motors)

Remember, this worksheet lists average power requirements — a particular manufacturer's device may use more or less than the listed wattage.

• Add a 10% correction factor to your totals to help overcome this uncertainty.

If your customer plans to operate devices that use electric motors, list both the starting and running requirements of each.

• Starting requirements of some devices maybe significantly higher than their running requirements. This higher demand must be considered when estimating your power needs. Some small, universal motors — which do not draw a heavy starting load (drills, small saws, blenders, etc.) — require very little extra current for starting.

When listing items that use motors, take them in the order of highest-to-lowest starting requirements, as shown in the example below. Motor A, for instance, has a starting requirement of 2,600 watts, so it's listed first, followed by Motor B at 1,300 watts, and Motor C at 1,000 watts.

Once you have compiled an accurate list of what you will be operating, you can calculate the maximum power requirements. There are three different calculations you can make, depending upon the kinds of tools and appliances on the list, and their intended use:

• No electric motors.
• One motor running at a time.
• More than one motor running at a time.

NO ELECTRIC MOTORS
If your list does not include any devices that use electric motors, simply add the power (running) requirements of all the items on your list to obtain the maximum power needed.

• For example, if you intend to use only an electric skillet, a 100-watt light and a heating pad (as shown below), the maximum power requirement would be 1,655 watts. In this case, a generator like the EF2800i, that can produce 2,500 watts rated output, is recommended.

NOTE: The EF1600's rated output is 1,400 watts, so its output would be too low to handle this load on a continuous basis.

Footnotes:
*Running Watts is the amount of power a motor consumes once it has started to run at normal speed.
**932 is the factor used to convert motor horsepower ratings to needed electrical energy. It takes into account normal losses in utilizing that power.