RELAY PROTECTION AGAINST CHANGE OF THE CHANGE OF PHASES OF THE SUPPLY NETWORK
There are various options for the design of the relay to protect against phase rotation. All such decisions have certain disadvantages, mainly insufficient reliability due to the significant number of elements and the presence of semiconductor components (diodes, thyristors, transistors) in the relay. Modern products of this kind can be performed on microcontrollers, however, this also has its drawbacks - for example, sensitivity to interference in the power supply network or the microcontroller program freezing. In earlier solutions, it is difficult to use protection relays in high-voltage industrial networks, since there is a direct galvanic connection between the elements and the supply network. This means that the requirements for the rated voltage of semiconductor circuit elements must significantly exceed the voltage level in the supply network. The proposed solution improves the design of the relay protection against phase rotation, makes it more reliable and convenient. Undoubtedly, such a relay is in demand in industrial plants, and helps protect consumers (especially electric drives of various kinds, including pumps) from incorrect phase rotation. Incorrect connection of the motor to the phases of the supply network leads to the reverse direction of its rotation, which is unacceptable for some types of actuators. The difference of the proposed solution is the design based on the solid-state relay and increasing the reliability of its operation, with a fairly small number of parts.