An isolator is a mechanical switch designed to completely disconnect a part of an electrical system from the power source for safety purposes. Its primary function is to isolate electrical circuits for maintenance or repair by ensuring there is no residual voltage or current present in the isolated section.
Isolators are often used in high-voltage and low-voltage electrical systems to provide a visible break in the circuit, indicating that it is safe to work on.
IEC 60947-3 functions
Isolators are designed in compliance with IEC 60947-3 and perform the following functions:
- Switching: ON/OFF
- Isolation
Automatic tripping functions
They are operated manually and used to disconnect or reconnect a circuit under no-load conditions
Unlike circuit breakers or fuses, which are used to protect systems from faults such as overloads or short circuits, isolators do not have automatic tripping functions.
They are operated manually and used to disconnect or reconnect a circuit under no-load conditions, meaning the current flow should already be interrupted by other protective devices, such as circuit breakers.
Types of Isolators
Isolators are offered in Single Pole, Double Pole, Three Pole & Four Pole Variants in various current ratings such as 25A, 40A, 63A, 80A, 100A, and 125A.
There are various types of isolators used depending on the application, system configuration, and voltage level. Here are some common types:
- Single Break Isolator
- Double Break Isolator
- Pantograph Isolator
- Line Isolator
- Bus Isolator
- Maintenance Isolator
What is an isolation?
Isolation refers to the process of completely disconnecting an electrical circuit or equipment from the power supply to ensure safety during maintenance or troubleshooting.
It guarantees that no electrical current or voltage is present in the isolated section of the system. Isolation is critical to protect workers from electric shocks and prevent equipment damage.
When isolation occurs:
- All power connections are physically separated.
- Any stored energy, such as capacitive or inductive loads, is discharged.
- There is no possibility of accidental energization of the system, as the isolator provides a visible open gap that confirms the disconnection.
Isolation means complete disconnection of the supply from the circuit. Isolator in OFF position must satisfy the conditions required for isolation as per IEC 60947-3.
Applications
Isolators are widely used in various industries and electrical systems to provide safety and operational benefits. Some common applications include:
- High-Voltage Substations
- Power Generation Plants
- Transmission and Distribution Networks
- Industrial Manufacturing
- Renewable Energy Systems
- Railways and Electrified Transport
Safe disconnection of circuits
Isolators are essential components in electrical systems for ensuring the safe disconnection of circuits during maintenance or repair.
They come in various types, each designed for specific applications, voltage levels, and system configurations. Proper isolation not only ensures worker safety but also protects equipment from accidental energization during service work.
