In commercial shipping, a three-phase alternating current system with a frequency of 60 hz has prevailed over the last decades. The power grid  in Germany has a frequency of 50 hz. Only a few devices can operate with 50 hz and 60 hz. Microwave ovens are usually designed only for power supply of 50 hz or 60 hz. For example, if you connect a programmable microwave oven designed to be connected to a 50 hz power supply, to a 60 hz power supply it will make the set-time run faster. You could possibly accept that. However, the entire electronics will also run faster and be charged higher. This can lead to the situation that the microwaves no longer transmitting at the set frequency, which have to be avoided at all costs. In addition, the components may overheat and break. This results in an increased risk of fire. Therefore, you always have to check the power supply of the ships before connecting a device. For exactly these on-board networks, the offered microwave ovens are intended. The semi-professional device is ideal for use on ship fair or in kitchen to quickly reheat small quantities of food. The commercial microwave oven is the ideal appliance for use in the galley when high power is needed. So, for example for rapid heating or for heating larger quantities of products.