1, power tools: many power tools, such as angle grinders, drills, polishers, etc., use AC or DC power supplies with a frequency of 700Hz or higher.
2, household appliances: such as cordless phones, radios, microwave ovens, etc., the power supply part of these devices will use a frequency of 700Hz.
3, professional equipment: professional equipment such as medical equipment and industrial equipment, may use 700Hz or higher power supply.