Dividend investing is a tried-and-true strategy for generating strong, steady returns in economies both good and bad. But as corporate America's slew of dividend cuts and suspensions over the past few years has demonstrated, it's not enough simply to buy a high yield. You also need to make sure those payouts are sustainable.

Let's examine how Duke (NYSE: DUK) stacks up. In this series, we consider four critical factors investors should examine in every dividend stock. We'll then tie it all together to look at whether Duke is a dividend dynamo or a disaster in the making.

1. Yield
First and foremost, dividend investors like a large forward yield. But if a yield gets too high, it may reflect investors' doubts about the payout's sustainability. If investors had confidence in the stock, they'd be buying it, driving up the share price and shrinking the yield.

Duke yields 4.7%, quite a bit higher than the S&P 500 2.1%.

2. Payout ratio
The payout ratio might be the most important metric for judging dividend sustainability. It compares the amount of money a company paid out in dividends last year to the earnings it generated. A ratio that's too high -- say, greater than 80% of earnings -- indicates that the company may be stretching to make payouts it can't afford, even when its dividend yield doesn't seem particularly high.

Duke has a payout ratio of 72%.

3. Balance sheet
The best dividend payers have the financial fortitude to fund growth and respond to whatever the economy and competitors throw at them. The interest coverage ratio indicates whether a company is having trouble meeting its interest payments -- any ratio less than 5 times is a warning sign. Meanwhile, the debt-to-equity ratio is a good measure of a company's total debt burden.

Let's examine how Duke stacks up next to its peers:

Company

Debt-to-Equity Ratio

Interest Coverage

Duke 88% 3 times
PPL (NYSE: PPL) 167% 3 times
Progress Energy (NYSE: PGN) 128% 3 times
Southern Company (NYSE: SO) 111% 4 times

Sources: S&P Capital IQ.

Duke carries a fair bit of debt, but that's not unusual for utilities, as they operate in a stable, capital-intensive industry.

4. Growth
A large dividend is nice; a large, growing dividend is even better. To support a growing dividend, we also want to see earnings growth.

Company

3-Year Annual Earnings per Share Growth

3-Year Dividend per Share Growth

Duke 10% 3%
PPL 5% 2%
Progress Energy (3%) 0%
Southern Company 2% 4%

Sources: S&P Capital IQ.

The Foolish bottom line
Duke exhibits a clean dividend bill of health. It has a generous yield, and modest payout ratio, negligible debt, and growth to boot. So Duke could very well be a dividend dynamo. If you're looking for other great dividend stocks, check out "Secure Your Future With 11 Rock-Solid Dividend Stocks," a special report from the Motley Fool about some serious dividend dynamos. I invite you to grab a free copy to discover everything you need to know about these 11 generous dividend-payers -- simply click here.