Changeover switches and isolator switches are both types of electrical switches used in electrical systems for different purposes. Here are the main differences between them:

1. Function:

   • Changeover Switch: A changeover switch, also known as a transfer switch, is used to switch power supply between two different sources or circuits. It allows for manual or automatic transfer of electrical loads from one power source to another in the event of a power failure or maintenance.
   • Isolator Switch: An isolator switch, also known as a disconnect switch or main switch, is used to physically disconnect electrical equipment or circuits from their power supply. It is primarily used for isolating equipment for maintenance, repair, or safety purposes.

2. Operation:

   • Changeover Switch: A changeover switch typically has three positions - one for each power source (such as mains power and backup generator) and a center position for off. It allows for switching between the two power sources or circuits by manually selecting the desired position.
   • Isolator Switch: An isolator switch has two positions - on and off. It is used to manually open or close the electrical circuit, physically disconnecting or connecting the power supply to the equipment or circuit.

3. Contacts:

   • Changeover Switch: A changeover switch has multiple sets of contacts to switch between different power sources or circuits. These contacts are designed to handle the electrical load and transfer it safely from one source to another.
   • Isolator Switch: An isolator switch typically has one set of contacts for opening and closing the electrical circuit. These contacts are designed to provide reliable isolation and ensure safe disconnection of the power supply.

4. Application:

   • Changeover Switch: Changeover switches are commonly used in backup power systems, such as standby generators or uninterruptible power supplies (UPS), to switch between mains power and backup power sources. They are also used in industrial applications for load shedding or transferring between different electrical systems.
   • Isolator Switch: Isolator switches are used in various electrical installations to isolate equipment or circuits for maintenance, repair, or safety reasons. They are often installed as main switches for electrical panels, machinery, or large appliances to provide a means of disconnecting power.

5. Safety:

   • Changeover Switch: Changeover switches are designed to ensure safe transfer of power between different sources or circuits, often incorporating features such as interlocks or mechanical and electrical interlocking systems to prevent accidental switching.
   • Isolator Switch: Isolator switches are designed to provide safe isolation of equipment or circuits, with features such as visible isolation points, padlocking facilities, and robust construction to ensure reliable operation and safety.

In summary, changeover switches are used to switch between different power sources or circuits, while isolator switches are used to physically disconnect equipment or circuits from their power supply for maintenance, repair, or safety purposes. Both types of switches serve critical functions in electrical systems and are selected based on specific application requirements.