An intelligent power-switching device that operates on its own and is controlled by specific control logic is called an automated transfer switch (ATS). An automatic transfer switch (ATS) is primarily used to guarantee the uninterrupted supply of electrical power to a linked load circuit, such as lights, motors, computers, and other electrical equipment, from one of two power sources. For those looking to upgrade their power setup, new generators for sale in the UK often come with compatible options.
Your home’s ATS links your automated standby generator to the electrical system of your house when utility power goes out.
You won’t need to do anything; the ATS will reconnect your house to utility electricity and cut the generator’s power when utility power is restored. Your generator will automatically cool down and switch off when it is no longer required for electricity until it is again needed.
How ATS Operates
Usually based on a microprocessor, the control logic or automated controller continuously checks the electrical characteristics (voltage, frequency) of both primary and backup power sources. The ATS will automatically switch the load circuit to the alternate power source if the connected power source fails. Generally speaking, most automatic transfer switches will only connect to the backup power source when necessary or requested, and they will normally attempt to connect to the primary power source by default.
Activation of Backup Power Source
When electricity from the backup utility feed or generator is consistent and falls within specified voltage and frequency limitations, the transfer switch switches the load to the emergency power source. A facility may choose a manually started or self-acting transfer method, depending on its requirements and preferences.
Restoration of Utility Power
When utility power is restored, the transfer switch moves the load from the emergency power source to the regular power source. Retransfers can be manually started or self-acting.
Types of ATS Transitions
Open Transition
A break-before-make transfer is known as an open transition. Before connecting to the other power source, the transfer switch disconnects from the first one. Open-delayed and open-in-phase are examples of open transitions.
Closed Transition
A make-before-break transfer is known as a closed transition. Before cutting the connection with the first power source, the transfer switch connects to a second power source. Because there is never a pause between disconnecting and reconnecting, electricity is continuously sent to downstream loads.
Manual Operation
Transfer initiation and operation are done manually; the initiation happens locally and is usually accomplished by pushing a button or turning a lever.
Not Automated
Press a button or turn a switch to manually start a transfer, which will electrically operate the switching mechanism using an internal electromechanical device. The initiation can take place locally or remotely.
Self-Acting Operation
The self-acting ATS controller fully controls both initiation and operation. The switching mechanism operates once the automated controller detects a loss of source power or its unavailability.
Switching Mechanisms
Contactor Type
This form of switching mechanism is the most widely used and usually the least expensive. In contactor construction, one operator opens one set of power connections while shutting the other set. This type of switch is known as an electrically controlled double-throw switch.
Moulded Case Type
Moulded case switches are often used to close and interrupt circuits between detachable contacts in both normal and abnormal circumstances. Their straightforward designs allow them to accommodate a motor operator or an over-centre toggle that is manually driven.
Power Frame Type
Compared to moulded case switches, power frame switches are bigger, quicker, more powerful, and able to handle up to 5,000 amps. The device uses a two-step stored energy technique that enables both electrical and manual operation under stress.
Applications Affecting ATS Design
Neutral Switching
Transfer switches can be designed with a fully rated fourth pole that functions exactly like the individual phase (A, B, and C) power poles for three-phase power applications that need to switch the neutral wire. It is possible to design a fully-rated third pole for single-phase applications. When the transfer switch is powered by independently generated power sources, a switched neutral is frequently utilised.
Bypass Isolation
Automatic transfer switches with bypass isolation offer dual switching capabilities and redundancy for essential applications, resulting in easier maintenance and increased uptime. Daily distribution of electrical power to the load is managed by the primary ATS, while the bypass switch acts as a redundant or backup mechanism. To facilitate routine maintenance, inspection, and testing as required by code, a bypass isolation transfer switch is often chosen for use in healthcare and other critical applications. This is because it enables the ATS, and in certain cases the bypass switch, to be drawn out and isolated from the power source(s).
Service Entrance Transfer Switches
An ATS is frequently placed at the service entrance of buildings with a single utility connection and emergency power source to guarantee that important loads can switch to emergency power in a timely and safe manner if utility power is interrupted. To prevent capacity overload, non-critical loads are frequently suppressed or disconnected from the emergency power supply.
