A Comparison of Methods for Determining the Wattage Output and Energy Distribution in Microwave Ovens

Two characteristics of microwave ovens that are important to consumers as they select and use microwave ovens are the wattage output (cooking power) and the evenness of distribution of energy within the oven cavity. Several test methods have been proposed to measure each of these characteristics, but there is not agreement in the industry on realistic methods of their measurement. The purpose of this study is to evaluate a variety of methods for determining cooking power and energy distribution. Cooking power was measured using the temperature rise of water loads. The influence of initial load temperature, quantity of water, profile, and location of the load within the cavity (centrally located versus dispersed) was determined. Energy distribution was measured using nonfood loads (a three-dimensional copying paper load and various water loads), a simple food (gelatin), and a complex food (custard). Placement of the load, the profile, and the composition of the load affected the apparent energy distribution. Recommendations for standardized tests resulted from this research.