What device is used to connect and disconnect lines and equipment in an electrical grid?

The device used to connect and disconnect lines and equipment in an electrical grid is the circuit breaker. A circuit breaker is essentially a protective device that automatically interrupts the flow of current in the event of an overload or short circuit, ensuring that electrical systems operate safely and efficiently. Its ability to be reset after tripping also allows for easy reconnection, unlike fuses which need to be replaced after blowing.

In context, voltage regulators are used primarily for maintaining voltage levels within a specified range and do not directly serve the function of connecting or disconnecting equipment. Current transformers are utilized for measuring current in high voltage lines and for providing input to metering and protective devices, rather than for disconnecting loads. Isolator switches are important for ensuring that a circuit can be maintained safely by isolating it, but they are typically used in conjunction with circuit breakers and are not designed for automatic operation in overload situations.