The medium-voltage indoor load break switch (MV indoor LBS) , suitable for three-phase AC 10KV, 50HZ power system, is an electrical appliance whose function is between the vacuum circuit breaker and the medium voltage isolation switch. The MV indoor LBS is often used in series with the high-voltage fuse; it is used to control the power transformer. The LBS has a simple arc extinguishing device, so it can switch on and off a certain load current and overload current. However, it cannot disconnect the short-circuit current, so it is generally used in series with a high-voltage fuse for short-circuit protection.

Medium voltage load break switch combined electrical appliances are used with complete sets of power distribution equipment, ring main unit（RMU）, combined substations, etc., widely used in area network construction and reconstruction projects, industrial and mining enterprises, high-rise buildings and public facilities, etc., can be used as a ring network power supply or terminal, playing the role of power distribution, control, and protection. It has the advantages of large breaking capacity, safety and reliability, long electrical life, frequent operation, compact structure, small size, lightweight, and basically no maintenance. With breaking rated current, overload current.