What is Power Distribution Unit & Automatic Transfer Switch? - Lorbel Critical Power Services

In the present world, where there is high dependability on the electrical supply, discontinuation of the power supply can lead to great chaos. Consider a house, or an office without electrical connection and think about the degree of disorderliness that can take place. In case of power outage or grid failure, a business organization will be forced to stop all the production work causing the corporation to incur massive downtime. Given that most of our household appliances operate with the help of electricity, incessant electrical supply is imperative for the smooth functioning of the household.

Here, we will be discussing two of the most vital devices in power distribution and transmission industry – Power distribution unit (PDU) and Automatic transfer switch (ATS) – which provides useful benefits to the users.

What is a Power Distribution Unit?

Also known as the main distribution unit or MDU, a power distribution unit is a device with multiple outputs that are used to control and distribute electric power, mainly to racks of computers and networking devices installed within a data center.

Data centers often face problems related to power protection and management solutions. For this reason, the power distribution unit in a data center comes into use as it improves efficiency, growth, and uptime of the facility.

Different Types of PDU

There are different types of PDUs, which are explicitly stated below.

Basic Form of PDU

The elementary form of power distribution unit consists of a large power strip devoid of any type of surge protection. It serves the purpose of providing standard electrical outlets for the equipment of data center and does not allow monitoring or remote accessing.

Rack-Mounted and Floor-Mounted Power Distribution Unit

Power distribution units ranging from simple and cheap rack-mounted power strips to multi-functional, huge floor-mounted PDUs are available in the market. These types of PDUs provide data that finds usability for determining power usage effectiveness (PUE). These PDUs offer various advantages, such as upgrading power quality, power filtering, intelligent load balancing, and remote monitoring and control by a local area network (LAN) or Simple Network Management Protocol (SNMP).

A rack-mountable PDU is installed directly to a device rack, which can monitor and control power to certain switches, servers, and other data center devices and is useful for balancing power loads. Having different names like intelligent PDUs and smart PDUs, rack-mountable PDUs come with three-phase displays for the equipment sharing power well, that offers the remote management function. It uses the Simple Network Management Protocol (SNMP) that enables the authorities of a business organization to regulate and monitor power demands from other locations.

A floor-mounted PDU supports a significant management bridge between a building’s primary power and the different equipment racks located within a data center or network operations center (NOC). A single PDU can manage a greater amount of energy when compared to an ordinary power strip (ranging from 300 kilovolt-amps and upwards, in accordance with the model and the manufacturer). It generally supplies power to more than one equipment rack.

The newer intelligent PDUs have usability in internet protocol (IP) consolidation, or multiple PDUs can also be linked in ordered series under a single IP address. The latest PDU models also facilitate integration with electronic locks, allowing to manage network PDUs and locks with the help of the same appliance.

Power Distribution Unit for Server Racks or Server Cabinets

There is a requirement of large PDUs in data centers, to provide power to several server cabinets or server racks. Multiple high current circuits from different UPS or uninterrupted power supply units are needed for each server cabinet or row of cabinets. Self-contained cabinet PDUs operate independently and include units like main breakers, power monitoring panels, and individual circuit breakers. The cabinet includes built-in bus bars for neutrality and grounding. There is also sufficient provision of bottom panels and a pre-punched top to facilitate safe cable entry.

Movable Power Distribution Unit

A movable power distribution unit provides comprehensive application space coverage facility and offers various functionalities, such as power distribution, power transformation, and plug and play connectivity. Found with multiple features and benefits, especially in the realm of the workplace and home safety, movable PDUs are widely used by corporations and private citizens alike. These portable power distribution units have flexible configuration alternatives, which are compatible with their unique application requirements.

Automatic Transfer Switch (ATS)

An automatic transfer switch is an electrical switch that shifts the power supply between the primary source and backup source when there is discontinuation of power supply in either of the sources. Sensing a power failure in a primary power source, the ATS activates the alternative power source, like an uninterruptible power supply. It is also capable of starting up diesel generators, to operate electric appliances until the restoration of utility power.

An automatic transfer switch acts as an intermediary between the electrical equipment and source of power supply. It is essential to have uninterrupted power in the data center. For proper maintenance, the systems connected to the power grid must be properly checked and tested. To ensure the reliability of an ATS during a power failure, it should be regularly monitored by the data center administrators. As ATS units can pass large amounts of energy and that can create pressure on the electrical contacts, it is vital to conduct regular maintenance activities.

Now, let us understand how does an automatic transfer switch work by knowing the modes of operation of its many varieties.

Types of Automatic Transfer Switch

Automatic transfer switches fall into one of four categories, depending upon the operation and associated power interruption for which they are used.

Open Transition ATS

Also known as the break-before-make transfer switch, an open transition ATS is utilized in a system that can control the short interruption in power when switching between a primary source and backup power. This interruption is usually less than a second long but makes a safe transfer of power so that no equipment or people around the devices are in danger. This automatic transfer switch working principle includes the opening of the connected source before transferring energy to the alternative source.

Closed Transition ATS

A closed transition ATS, also known as a make-before-break transfer switch, is used in places where even a short pause in the power supply is not accepted. It has inbuilt systems that enable both power options to be run concurrently, and also allow for a smooth switchover, maintaining proper safety measures. A closed transition ATS is more critical and more expensive than the open transition version.

Soft Loading ATS

Similar to the closed transition ATS, a soft loading transfer switch can adjust the amount of electrical energy it handles in various situations. It is generally used to synchronize the sources while transferring live sources and joining them together with a ramp load impulse to the backup power option. It is also used to transfer power between the two sources with minimal voltage or frequency transition. Though quite expensive, it allows businesses to have better flexibility against multiple situations that might require backup power.

Static Transfer Switch

A static transfer switch makes use of power semiconductors, like silicon-controlled rectifiers (SCRs) to switch power between two sources. Due to the absence of mechanical moving parts, the transition of electrical power can be done rapidly. These transfer switches are used in places with independent and reliable power sources. The load must be protected from even a slight interruption of a quarter of the electrical power cycle, or from possible sags or surges in the primary power source.

In Conclusion

Now that you have detailed information about power distribution units and automatic transfer switches, you can make effective use of them in your business organization as well as at your home. It is suggested that you take professional help from a certified electrician in your area to install the ideal power distribution unit (PDU) and an automatic transfer switch (ATS) within your premises.