What Are The Two Types Of Automatic Transfer Switches?

Automatic transfer switches, popularly known as ATS, are the devices used to alternate between the main power supply and the emergency generator or backup power. These switches work automatically when there is a power outage or a voltage drop. The main function of an automatic transfer switch is to keep the power supply intact and continuous.

In general, there are two types of automatic transfer switches used to generate a stable power supply. They are:

Static Transfer Switches (STS)

The Static Transfer Switch, or STS, is a modern switch that has replaced the mechanical switches in recent times. The primary function of STS is to transfer the power source during an event of a failure automatically. The device has high switching speed, and it can switch the power source in a fraction of a second.

How does Static Transfer Switch work?

STS has two input power sources, with two outputs as load. During normal operations, the primary source acts as the primary input, and the secondary source acts as the backup input. During an outage, the output from the primary source is intercepted by the transfer switch, and the load is transferred to the secondary input. STS has high operational efficiency, and it does not require human intervention.

Advantages of Static Transfer Switch

STS has high switching speed and can switch the power source in less than 4 milliseconds.
It has low downtime during a power outage.

Static Transfer Switch does not have moving parts, and therefore it is more reliable than mechanical switches.
The device has high operational efficiency.
STS does not require any human intervention; hence, it is user-friendly.

Mechanical Transfer Switches (MTS)

Mechanical Transfer Switches, or MTS, are the traditional switches used for power transfer. The primary function of MTS is to alternate the power supply between the main power source and the backup power sources manually.

How does Mechanical Transfer Switch work?

MTS has two input power sources, with two outputs as a load. During a power outage, the operator of the facility has to switch the manual switch manually to transfer the load from the primary input to the secondary input. MTS has a slow switching speed because it requires human intervention.

Advantages of Mechanical Transfer Switch

Suitable for small-scale operations, and it is cost-effective.

It is easy to install.
Mechanical Transfer Switch does not require special training for human operators.
MTS requires low maintenance, and the components are easily repairable in the event of a failure.

The device has a high thermal stress tolerance, which makes it ideal for harsh environments.

Disadvantages of Mechanical Transfer Switch

MTS requires human intervention, which makes it less efficient than STS.
It has a slow switching speed, which can lead to longer downtime during a power outage.

MTS is not suitable for large scale operations because of the complications from the manual switching process.
The device is prone to wear and tear because of the mechanical components, which makes it less reliable.

In conclusion, both Static Transfer Switch and Mechanical Transfer Switch have their advantages and disadvantages. STS is more efficient, reliable, and effective, while MTS is less efficient but more cost-effective and suitable for smaller operations. The choice of automatic transfer switch depends on the needs of the facility and the power requirements.

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FAQs – What Are The Two Types Of Automatic Transfer Switches?

What are the two types of automatic transfer switches?

There are two types of automatic transfer switches: open transition and closed transition.

What is an open transition automatic transfer switch?

An open transition automatic transfer switch temporarily disconnects the load from the power source during the transfer process. It does this to avoid any damage or interference in the power source.

What is a closed transition automatic transfer switch?

A closed transition automatic transfer switch transfers the load from one power source to another without any interruption. It ensures a continuous power supply to the load while transferring power sources.

Which one is better: open transition or closed transition automatic transfer switch?

The choice between open transition and closed transition automatic transfer switch largely depends on the application and the load being supplied. If the load can handle short interruptions, an open transition switch can be used. However, if the load needs a continuous power supply, a closed transition switch would be more appropriate.