Yes it's some physical connection being broken. It's not unusual to adjust the ways in which the electrical grid is connected. See https://www.youtube.com/watch

Yes it's some physical connection being broken. It's not unusual to adjust the ways in which the electrical grid is connected. See https://www.youtube.com/watch?v=7Q-aVBv7PWM https://www.youtube.com/watch?v=7Q-aVBv7PWM from Practical Engineering which talks about some of the nuances of building switches which can break connections between different parts of the grid safely.