6. Are there any disadvantages to a masonry circuit?

The Steinmetz circuit is intended as a kind of emergency solution for households without a three-phase connection or for machines where you want to avoid the expense of wiring with three external conductors. The area of application is machines in which a rotary movement at a constant speed is to be generated as cheaply as possible. The disadvantage of the Steinmetz circuit is that the starting torque is limited to ⅓ of the rated motor torque. To achieve the same power, a larger motor must be used, which is more expensive and takes up more space. In addition, the efficiency is quite low at approx. 70 %. For economic reasons, the Steinmetz circuit was always limited to motors with an output of less than two kilowatts. With the advent of the three-phase frequency inverter, the field of application was further restricted, as this can generate the three-phase AC current required for a three-phase motor from a DC or AC voltage. This makes it possible to operate a three-phase motor on just one phase conductor without any restrictions. Three-phase motors in masonry circuits are used, for example, to drive concrete mixers, older washing machines and circulation pumps in heating systems. However, capacitor motors are often used there due to their simplicity.