Transfer Switches

Improve power redundancy for servers, network equipment, storage systems, security appliances, communications infrastructure, and other critical IT hardware with transfer switches from Hummingbird Networks. Automatic Transfer Switches can connect compatible equipment to two independent power sources and automatically transfer the load when the preferred source becomes unavailable or unstable.

Transfer switches are especially useful for single-corded IT equipment that cannot connect directly to two separate power sources. By providing primary and secondary power inputs, an Automatic Transfer Switch can add power-source redundancy to compatible servers, network switches, routers, firewalls, storage appliances, and other rack-mounted equipment.

Hummingbird Networks offers rack-mounted Automatic Transfer Switch solutions from APC and Eaton Tripp Lite Series for network closets, server rooms, edge computing environments, and enterprise data centers. Available configurations include 120V and 200-240V systems, NEMA and IEC connections, local metering, network monitoring, switched outlets, and rackmount designs.

Automatic Transfer Switches for IT Infrastructure

An Automatic Transfer Switch, commonly abbreviated ATS, connects compatible equipment to two available power sources and automatically selects the appropriate source according to the design of the system.

Transfer switches can be used with:

Servers
Network switches
Routers
Firewalls
Storage systems
Security appliances
Network video recorders
Communications equipment
Edge computing systems
Other single-corded IT equipment

The correct transfer switch depends on input voltage, amperage, output requirements, input plug type, outlet configuration, rack space, power capacity, monitoring requirements, and the two upstream power sources being used.

What Is a Transfer Switch?

A transfer switch allows connected equipment to receive power from more than one compatible electrical source.

In IT environments, an Automatic Transfer Switch normally has:

A primary power input
A secondary power input
One or more output receptacles
Automatic source monitoring
Automatic transfer between sources

The transfer switch normally powers connected equipment from the preferred source. If that source fails or becomes unacceptable, the switch transfers the load to the alternate source when that source is available and within supported conditions.

What Does an Automatic Transfer Switch Do?

An Automatic Transfer Switch monitors available power sources and changes the source supplying connected equipment when required.

A typical IT power architecture can be:

Primary Power Source + Secondary Power Source → Automatic Transfer Switch → IT Equipment

This arrangement can provide redundant power options for equipment that has only one power cord.

Why Use an Automatic Transfer Switch?

Many enterprise servers, switches, storage systems, and network appliances include dual power supplies and can connect directly to separate power paths.

Other equipment has only one electrical input.

An Automatic Transfer Switch can provide additional power-path redundancy for single-corded devices by connecting them to two upstream sources.

This can help reduce dependence on:

A single UPS
A single branch circuit
A single utility source
A single generator-backed source
A single rack power path

Automatic Transfer Switch vs. Manual Transfer Switch

Automatic and manual transfer switches differ primarily in how the power source is changed.

Automatic Transfer Switch

An Automatic Transfer Switch monitors available sources and performs the transfer automatically according to its supported operating logic.

Manual Transfer Switch

A manual transfer switch requires an operator to change the active source.

For IT environments requiring rapid response to a power-source failure, automatic switching is generally more appropriate than relying on someone to perform a manual transfer.

ATS Meaning in IT Power

ATS stands for Automatic Transfer Switch.

In rack and IT infrastructure, an ATS can provide source redundancy to single-corded equipment by automatically selecting between two compatible electrical inputs.

The term ATS is also commonly used for rack PDUs that combine power distribution with automatic source switching.

Automatic Transfer Switch PDU

An Automatic Transfer Switch PDU combines two functions:

Automatic transfer between primary and secondary power sources
Distribution of power to multiple output receptacles

This can allow one rack-mounted device to provide redundant input power and distribute that power to multiple pieces of IT equipment.

Current Hummingbird Networks inventory includes Eaton Tripp Lite Series Automatic Transfer Switch PDUs with metered, monitored, and switched configurations.

Transfer Switch vs. PDU

A standard Power Distribution Unit primarily distributes power to multiple devices.

An Automatic Transfer Switch selects between two power sources.

Some products combine both functions, providing:

Dual power inputs
Automatic source transfer
Multiple output receptacles
Metering
Remote monitoring
Outlet switching on selected models

For broader rack power distribution, explore PDUs and Power Distribution Units.

Transfer Switch vs. UPS

A transfer switch and an Uninterruptible Power Supply perform different functions.

UPS: Provides battery backup and power protection during a loss of utility power.

Transfer switch: Selects between two available electrical power sources.

The two technologies are often used together.

For example, a transfer switch can use two separate UPS systems as primary and secondary sources to provide redundant UPS-backed power to single-corded equipment.

Explore UPS Uninterruptible Power Supplies for battery-backup infrastructure.

Dual UPS Redundancy

One common use for an Automatic Transfer Switch is connecting a single-corded device to two separate UPS systems.

A typical architecture can be:

UPS A + UPS B → Automatic Transfer Switch → Single-Corded Equipment

If the preferred UPS becomes unavailable or its output falls outside supported conditions, the ATS can transfer the connected load to the alternate UPS when appropriate.

Selected Eaton Tripp Lite Series ATS products are specifically designed to provide redundant power for single-corded network equipment using separate primary and secondary power sources.

Primary & Secondary Power Sources

Automatic Transfer Switches typically identify two upstream sources as primary and secondary.

The primary source normally supplies connected equipment.

The secondary source remains available as an alternate.

Depending on the transfer switch, compatible sources can include:

Separate UPS systems
Separate utility circuits
UPS and utility power
Generator-backed circuits
Other compatible AC power sources

The two sources must meet the electrical and operating requirements of the transfer switch.

What Happens When the Primary Source Fails?

The ATS continuously evaluates the available sources.

If the primary source fails or moves outside supported conditions, the transfer switch can move the connected load to the secondary source.

When the preferred source returns and becomes stable, the ATS can return the load according to its transfer logic.

The exact behavior depends on the manufacturer and model.

Automatic Source Monitoring

Modern Automatic Transfer Switches can monitor the condition of both input power sources.

Depending on the model, the ATS can evaluate factors such as:

Source availability
Input voltage
Frequency
Power quality
Source stability

Selected Eaton Tripp Lite Series ATS products monitor both input sources and avoid transferring to the secondary source when the alternate source is unavailable or unsuitable.

Transfer Time

Transfer time describes how quickly an Automatic Transfer Switch changes from one source to another.

IT transfer switches are designed to perform this operation rapidly so compatible equipment continues operating through the transition.

Current Eaton Tripp Lite Series ATS products sold by Hummingbird Networks include models with transfers occurring within a few milliseconds. Exact transfer time varies by model and operating conditions.

Millisecond Power Transfer

Electronic IT equipment often includes power supplies capable of tolerating a brief interruption while an ATS changes sources.

Selected Eaton Tripp Lite Series transfer switches list transfer windows such as approximately 1-5 milliseconds or 2-7 milliseconds depending on the model.

Always verify that connected equipment is compatible with the transfer characteristics of the specific ATS.

Transfer Switches for Single-Corded Equipment

Single-corded equipment has only one AC power input and therefore cannot connect directly to two independent power paths.

An ATS can provide redundant source selection for these devices.

Common examples can include:

Network appliances
Routers
Firewalls
Security appliances
Storage devices
Communications equipment
Selected servers

Transfer Switches for Dual-Power-Supply Equipment

Equipment with two independent power supplies often does not require an ATS if each power supply can connect directly to a separate supported power path.

A dual-power-supply server can, for example, connect:

Power Supply 1 to PDU A
Power Supply 2 to PDU B

This provides direct A/B power redundancy.

An ATS is especially valuable where the connected equipment has only one power cord.

A/B Power Redundancy

A/B power architecture uses two separate power paths to reduce dependence on a single electrical source.

A typical redundant rack can include:

Power Path A
Power Path B
Separate UPS systems
Separate PDUs
Separate branch circuits

An Automatic Transfer Switch can connect single-corded equipment to both paths.

Transfer Switches for Server Racks

Server racks can contain a mixture of dual-corded and single-corded equipment.

Transfer switches can provide redundant source options for single-corded rack equipment while other devices connect directly to redundant PDUs.

When designing ATS power for servers and related equipment, consider:

Total connected load
Input voltage
Input current
Output receptacles
UPS compatibility
Transfer time
Rack space
Monitoring requirements

Transfer Switches for Network Equipment

Network infrastructure can require high availability because a loss of power to a single device can affect many users.

An ATS can provide redundant power-source options for compatible:

Network switches
Routers
Firewalls
Wireless controllers
Security appliances
Communications gateways

For critical network switches, determine whether the switch has one or multiple power supplies before designing the power architecture.

Transfer Switches for Firewalls

Firewalls can be critical to internet connectivity, VPN access, segmentation, and network security.

A single-corded firewall connected to one power source creates a potential power-path dependency.

An ATS can connect the firewall to two compatible sources and transfer between them when required.

Transfer Switches for Routers

Routers and gateways can provide WAN, internet, branch, and inter-site connectivity.

An Automatic Transfer Switch can add source redundancy to compatible single-corded routing equipment.

The connected router's power supply should support the ATS transfer characteristics and output voltage.

Transfer Switches for Storage Systems

Storage appliances can contain critical business data and may need redundant power infrastructure.

Many enterprise storage systems include dual power supplies, but smaller or specialized appliances can use a single power connection.

An ATS can provide redundant upstream power for compatible single-corded storage equipment.

Transfer Switches for Security Appliances

Physical-security systems can rely on recorders, controllers, access-control appliances, and networking equipment that must remain powered.

Automatic source transfer can help reduce dependence on a single power path for compatible security infrastructure.

Transfer Switches for Edge Computing

Edge computing places network and compute equipment in branch offices, retail sites, warehouses, healthcare facilities, manufacturing environments, and remote locations.

Power redundancy can be especially useful where local technical staff are not continuously present.

Network-managed ATS products can help administrators monitor power remotely while providing redundant power-source options.

Transfer Switches for Network Closets

Network closets often support critical switching, routing, firewall, communications, and wireless infrastructure.

An ATS can provide redundant source power to compatible single-corded equipment where two electrical sources or UPS systems are available.

Important considerations include:

Rack space
Available circuits
UPS capacity
Voltage
Equipment load
Remote monitoring

Transfer Switches for Server Rooms

Server rooms can combine multiple electrical paths, UPS systems, PDUs, servers, storage, networking, and security infrastructure.

Transfer switches can be used selectively for equipment that cannot connect directly to redundant power paths.

A broader server-room power strategy can include:

UPS systems
A/B power distribution
Rack PDUs
Automatic Transfer Switches
Generators
Network power monitoring

Transfer Switches for Data Centers

Data centers frequently use redundant electrical architectures to reduce single points of failure.

An ATS can play an important role where single-corded devices must operate within a redundant A/B power environment.

Data center ATS planning should consider:

Source independence
UPS architecture
Rack power distribution
Input voltage
Connected load
Transfer time
Network management
Maintenance procedures

Rackmount Transfer Switches

Rackmount Automatic Transfer Switches are designed to install directly within standard IT racks.

Common configurations include:

1U rackmount ATS
2U rackmount ATS
Rack or wall-mount configurations on selected products

The appropriate form factor depends on electrical capacity, outlet count, management features, and available rack space.

1U Automatic Transfer Switches

1U transfer switches provide redundant power-source functionality while consuming a single horizontal rack unit.

Current Hummingbird Networks inventory includes 1U APC NetShelter Automatic Transfer Switches and multiple 1U Eaton Tripp Lite Series ATS PDU configurations.

2U Automatic Transfer Switches

Higher-capacity Automatic Transfer Switches can require 2U of rack space.

Current products include higher-amperage and higher-voltage configurations designed for larger rack loads.

Hummingbird Networks currently lists Eaton Tripp Lite Series 2U ATS products and APC 30A transfer-switch configurations.

120V Transfer Switches

120V Automatic Transfer Switches are commonly used in North American offices, network closets, branch locations, and smaller server environments.

Current Eaton Tripp Lite Series configurations include 120V systems with:

NEMA 5-15P inputs
NEMA 5-20P inputs
NEMA L5-20P inputs
NEMA 5-15R outputs
NEMA 5-15/20R outputs

The ATS input plug and output receptacles must match the upstream power sources and connected equipment.

208V Transfer Switches

208V Automatic Transfer Switches are common in enterprise server racks and data centers where higher-voltage power distribution is used.

Current Hummingbird Networks products include APC NetShelter Automatic Transfer Switches designed for 200/208V and 208V environments.

230V & 240V Transfer Switches

200-240V ATS products support higher-voltage IT environments and international power architectures.

Current Eaton Tripp Lite Series transfer switches include configurations with 200V, 208V, 220V, 230V, and 240V output support.

Single-Phase Transfer Switches

Single-phase Automatic Transfer Switches are common in network racks, server rooms, branch infrastructure, and enterprise IT.

Current Hummingbird Networks Eaton Tripp Lite Series ATS products include single-phase systems across both 120V and 200-240V electrical environments.

NEMA Transfer Switches

NEMA electrical connections are common in North American IT power environments.

Current transfer-switch configurations include connection types such as:

NEMA 5-15P
NEMA 5-20P
NEMA L5-20P
NEMA L6-20P
NEMA L6-30P
NEMA 5-15R
NEMA 5-15/20R
NEMA L6-30R

The connector must match both voltage and current requirements.

IEC Transfer Switches

IEC connections are widely used on servers, network switches, storage systems, and enterprise rack infrastructure.

Current Hummingbird Networks transfer-switch products include IEC configurations such as:

IEC C20 inputs
IEC C13 outputs
IEC C19 outputs

IEC-based ATS products are particularly common in higher-voltage rack environments.

C13 & C19 ATS Outlets

Automatic Transfer Switches with both IEC C13 and C19 outlets can support a mixture of standard and higher-power IT equipment.

Current Eaton Tripp Lite Series ATS configurations include combinations such as eight C13 and two C19 output receptacles.

ATS Amperage

Transfer switches are available for different current ratings depending on the electrical environment.

Common current configurations include:

The ATS, branch circuit, UPS output, input connectors, and connected equipment must all be electrically compatible.

15A Transfer Switches

15A Automatic Transfer Switches can support lower-capacity 120V IT loads.

Current Eaton Tripp Lite Series products include 120V 15A ATS PDUs with dual 5-15P inputs and multiple 5-15R output receptacles.

20A Transfer Switches

20A ATS systems provide additional electrical capacity for compatible rack environments.

Current Hummingbird Networks inventory includes 120V Eaton Tripp Lite Series 20A ATS products using NEMA L5-20P or 5-20P input configurations.

30A Transfer Switches

30A transfer switches support larger rack loads in compatible electrical environments.

Current Hummingbird Networks listings include 30A APC and Eaton Tripp Lite Series Automatic Transfer Switch configurations for higher-capacity IT equipment.

Metered Automatic Transfer Switches

Metered ATS products provide electrical-load information in addition to automatic source switching.

Current Eaton Tripp Lite Series metered ATS products can provide local digital current monitoring so administrators can understand total connected load.

Load metering can help administrators:

Reduce overload risk
Understand current equipment demand
Plan additional equipment
Monitor rack capacity

Monitored Automatic Transfer Switches

Network-monitored ATS products provide remote power visibility.

Depending on the product, administrators can monitor:

Power-source status
Load level
Input conditions
Transfer events
Equipment status

Current Hummingbird Networks inventory includes Eaton Tripp Lite Series ATS products with integrated network-management capabilities.

Switched Automatic Transfer Switches

Switched ATS PDUs combine automatic source transfer with remotely controllable output receptacles.

Depending on the model, this can allow administrators to:

Turn individual outlets on or off
Remotely reboot equipment
Control startup sequences
Control shutdown sequences
Disable unused outlets

Current Hummingbird Networks inventory includes Eaton Tripp Lite Series switched ATS products with network management and individual outlet control.

Remote Reboot with a Transfer Switch PDU

A switched ATS PDU can provide two important capabilities at the same time:

Power-source redundancy
Remote outlet control

If a connected network appliance becomes unresponsive, an administrator may be able to power-cycle its outlet without traveling to the equipment location.

This can be particularly useful for remote offices and edge infrastructure.

Network-Managed Transfer Switches

Network-managed transfer switches can provide remote visibility and control through an IP network.

Depending on the model, management can include:

Web-based administration
SNMP monitoring
Power-source status
Load monitoring
Event alerts
Remote outlet control

Network management can be especially valuable for unattended or geographically distributed IT sites.

Transfer Switch Alerts

Managed ATS products can provide alerts when power conditions change.

Depending on the system, administrators can be notified about:

Primary-source failure
Source transfer
Load conditions
Power restoration
Management events

Remote alerting can help administrators investigate electrical problems even when connected equipment remains operational through the alternate source.

APC Automatic Transfer Switches

APC offers NetShelter Rack Automatic Transfer Switches for enterprise rack and data center power environments.

Current Hummingbird Networks inventory includes APC NetShelter ATS models with configurations such as:

1U rack mounting
16A operation
20A operation
30A operation
200/208V operation
230V operation
Dual power inputs
IEC C13 and C19 outputs

APC ATS products should be selected according to the exact input power architecture and equipment load.

APC NetShelter Rack Automatic Transfer Switches

APC NetShelter Rack Automatic Transfer Switches are designed to provide redundant input power to compatible single-corded IT equipment.

The live Hummingbird Networks Transfer Switches category currently includes an APC NetShelter 1U 16A 230V ATS with dual C20 inputs and C13/C19 outputs.

Other current Hummingbird catalog listings include APC 20A and 30A 200/208V NetShelter ATS configurations.

Eaton Tripp Lite Series Transfer Switches

Eaton Tripp Lite Series offers Automatic Transfer Switch PDUs for rack-mounted IT infrastructure.

Current Hummingbird Networks products include:

120V ATS PDUs
200-240V ATS PDUs
15A configurations
20A configurations
30A configurations
Metered ATS products
Monitored ATS products
Switched ATS products
NEMA connections
IEC connections

Eaton Tripp Lite Metered ATS

Metered Eaton Tripp Lite Series Automatic Transfer Switches combine source redundancy with local current monitoring.

Current 120V models sold by Hummingbird Networks provide multiple NEMA output receptacles and digital load monitoring for rack and network environments.

Eaton Tripp Lite Switched ATS

Switched Eaton Tripp Lite Series ATS products add network-based outlet control to redundant input power.

Selected current models can provide:

Dual AC inputs
Automatic source transfer
Individual outlet control
Remote power cycling
Network management

Hummingbird Networks currently carries 120V and 200-240V switched ATS configurations.

Eaton Tripp Lite Monitored ATS

Monitored ATS products provide redundant power inputs together with network-based load and source visibility.

Current Hummingbird Networks inventory includes a 3.8kW 200-240V monitored Eaton Tripp Lite Series ATS with dual C20 inputs, C13 and C19 outputs, and an integrated network card.

Automatic Transfer Switches & UPS Maintenance

Transfer switches can also help support UPS maintenance strategies.

In supported designs, an ATS can allow equipment to use an alternate power path while one upstream UPS is serviced or replaced.

The exact architecture depends on the ATS, UPS systems, maintenance requirements, and power-source design.

Hot-Swappable UPS Maintenance

Selected Eaton Tripp Lite Series ATS products are designed to support redundant UPS configurations and can assist with hot-swappable UPS maintenance strategies.

Organizations should plan UPS maintenance carefully so the alternate path has sufficient capacity to support the complete connected load.

Transfer Switches & Generators

Automatic Transfer Switches can be part of power architectures that include generator-backed sources.

Depending on the design, the ATS inputs can connect to compatible sources such as:

UPS output
Utility circuits
Generator-backed circuits

The specific power architecture should be designed around voltage, frequency, capacity, equipment requirements, and applicable electrical standards.

Transfer Switches & Separate Utility Circuits

Two independent branch circuits can provide redundant input options for compatible ATS deployments.

Using separate upstream paths can reduce the chance that one branch-circuit failure removes power from the connected equipment.

The degree of redundancy depends on how independent the upstream electrical paths actually are.

Source Independence

True power redundancy depends on avoiding shared single points of failure upstream.

Two ATS input cords connected to receptacles on the same failed circuit do not provide meaningful circuit redundancy.

When high availability is required, organizations should evaluate:

Branch circuits
UPS systems
PDUs
Electrical panels
Utility sources
Generators

Transfer Switch Load Capacity

The connected equipment load must remain within the supported power rating of the Automatic Transfer Switch.

Capacity can be specified using:

Amps
Watts
Volt-amperes
Kilowatts

The upstream sources must also have enough capacity to support the entire connected load after a transfer.

Why Both Power Sources Must Support the Load

The secondary source should be sized to support the complete ATS load because it can become the active source when the primary source fails.

Connecting a large load to an ATS does not reduce that load when the source changes.

Both power paths should therefore be designed for the required equipment demand.

Transfer Switch Capacity Planning

Before selecting an ATS, calculate the expected load of all equipment connected to the switch.

Consider:

Normal operating load
Peak load
Equipment startup conditions
Future equipment growth
Upstream UPS capacity
Branch-circuit limits

Automatic Transfer Switch Overload Protection

Selected ATS products include circuit protection or overload protection.

Current Eaton Tripp Lite Series models list overload or circuit-protection features on supported products.

Protection features do not replace proper power-system sizing.

Transfer Switch Redundancy Planning

An ATS adds redundancy only when both upstream paths are appropriately designed.

A complete plan should consider:

Independent sources
UPS redundancy
PDU redundancy
Circuit redundancy
ATS capacity
Connected equipment power supplies
Monitoring

Can an ATS Eliminate All Power Failure Risk?

No. An Automatic Transfer Switch reduces dependence on a single power source but does not eliminate every possible failure.

Potential remaining dependencies can include:

The ATS itself
Downstream power cabling
The equipment power supply
Shared upstream electrical infrastructure
Facility-level power failures

Critical environments should evaluate the complete power chain.

ATS & Power Quality

A transfer switch must determine whether the alternate power source is acceptable before moving the load.

Selected ATS products monitor input-source quality and can avoid transferring to a secondary source that is unavailable or unsuitable.

Can Two ATS Inputs Be Out of Phase?

Support for sources with different phase relationships depends on the ATS architecture.

Selected Eaton Tripp Lite Series products are designed to support compatible primary and secondary AC sources regardless of phase angle.

Always follow the manufacturer requirements for the specific transfer switch.

Automatic Transfer Switch LEDs & Displays

Transfer switches can include front-panel indicators that show power-source and load status.

Depending on the model, indicators can display:

Primary source availability
Secondary source availability
Active source
Load current
Alarm conditions

Metered models can also include digital current displays.

ATS Remote Monitoring

Remote ATS monitoring can help administrators identify source failures even when connected equipment continues operating from the alternate source.

This is important because redundancy can temporarily hide an upstream failure from end users.

Without monitoring, the organization might remain unknowingly dependent on the secondary source until another power event occurs.

Why Monitoring Redundant Power Matters

A successful ATS transfer keeps equipment online, but the transfer itself indicates that part of the power infrastructure has changed state.

Administrators should be able to identify:

Which source failed
Which source is active
Current load
Whether redundancy has been restored

This allows the failed power path to be repaired before another outage occurs.

Transfer Switches for Remote Offices

Branch offices and remote facilities can benefit from ATS products that combine source redundancy with network monitoring.

If the primary power path fails, the ATS can transfer to the secondary source while IT staff receive notification remotely.

Transfer Switches for Edge Sites

Edge computing environments can operate in locations without on-site IT staff.

Network-managed transfer switches can provide:

Redundant source power
Remote power monitoring
Transfer-event visibility
Remote outlet control on supported models

Transfer Switches for Critical Network Services

Internet gateways, firewalls, WAN routers, and other network devices can represent critical single points of failure.

Where these devices use only one power input, an ATS can help provide power-source redundancy without replacing the device.

Transfer Switches for Communications Equipment

Business communications can depend on network appliances, routers, gateways, call-control equipment, and other devices.

Automatic source transfer can help maintain power to compatible single-corded communications equipment during an upstream source failure.

Automatic Transfer Switch Installation

ATS installation requirements vary by model.

A typical rack ATS installation can involve:

Mounting the ATS in the rack
Connecting the primary source
Connecting the secondary source
Connecting IT equipment
Verifying source status
Confirming connected load
Configuring network management when supported
Testing source transfer according to manufacturer procedures

Testing an Automatic Transfer Switch

Transfer functionality should be verified according to the manufacturer's supported test procedure.

Testing can help confirm that:

Both sources are available
The load remains within capacity
The ATS transfers as expected
Monitoring reports the event
Connected equipment continues operating

Testing critical power infrastructure should be planned carefully to reduce risk to production equipment.

Transfer Switch Maintenance

Transfer switches should be included in broader rack and electrical maintenance planning.

Maintenance can include:

Reviewing load levels
Checking input and output connections
Testing transfer operation
Reviewing event logs
Checking network management
Inspecting cables and connectors

How to Choose an Automatic Transfer Switch

Start with the equipment being powered and the available electrical sources.

Identify the Connected Equipment

Determine which servers, switches, routers, firewalls, storage appliances, or other devices require redundant source power.

Confirm the Equipment Is Single-Corded

Equipment with two independent power supplies can often connect directly to two separate power paths without an ATS.

Determine the Input Voltage

Verify whether the available power sources provide 120V, 208V, 230V, 240V, or another supported voltage.

Determine Required Amperage

Select an ATS compatible with the branch circuit, upstream UPS systems, and equipment load.

Check Input Connectors

Verify NEMA or IEC input compatibility with both power sources.

Check Output Receptacles

Make sure the ATS provides the connection types required by the equipment.

Calculate the Load

Add the expected electrical consumption of all connected devices.

Check Transfer Time

Verify that connected equipment can tolerate the transfer characteristics of the ATS.

Choose Local or Network Monitoring

Determine whether administrators need only front-panel status or remote management and alerting.

Consider Outlet Switching

Remote sites can benefit from switched ATS products that provide outlet-level power control.

Check Rack Space

Determine whether the system requires 1U, 2U, or another mounting configuration.

Automatic Transfer Switch Selection Checklist

Before purchasing an ATS, verify:

Connected equipment
Number of equipment power cords
Primary source
Secondary source
Input voltage
Output voltage
Input amperage
Input plug type
Output receptacle types
Outlet quantity
Total equipment load
Transfer time
Rack height
Local metering requirements
Network monitoring requirements
Outlet switching requirements
UPS compatibility

Building a Redundant Rack Power Architecture

An Automatic Transfer Switch is one part of a larger redundant power strategy.

A complete environment can include:

Multiple electrical sources
Redundant UPS systems
A/B rack PDUs
Automatic Transfer Switches
Dual-power-supply servers
Generator backup
Remote power monitoring
Environmental monitoring

Explore Power & Cooling for the broader infrastructure used to protect and distribute power throughout business IT environments.

Transfer Switches & Rack Infrastructure

Transfer switches are commonly installed inside the same equipment racks as servers, switches, storage, UPS systems, and PDUs.

Rack planning should consider:

Available rack units
Equipment weight
Power-cord routing
Access to input connections
Airflow
Service access

Explore Racks & Infrastructure when planning the physical environment supporting redundant power equipment.

Why Buy Transfer Switches from Hummingbird Networks?

Automatic Transfer Switch selection requires careful matching of voltage, current, connectors, output receptacles, equipment load, UPS architecture, transfer time, rack space, and management requirements.

Hummingbird Networks offers rack Automatic Transfer Switch solutions for network closets, server rooms, edge infrastructure, and data centers from leading power-management manufacturers.

Customers can turn to our team for:

Automatic Transfer Switches
Rackmount ATS systems
1U transfer switches
2U transfer switches
120V transfer switches
208V transfer switches
230V and 240V transfer switches
NEMA ATS systems
IEC ATS systems
Metered transfer switches
Monitored transfer switches
Switched transfer switches
APC NetShelter Automatic Transfer Switches
Eaton Tripp Lite Series ATS PDUs
Redundant rack power solutions
Product and compatibility guidance

Whether you need to add redundant power to a single-corded firewall, maintain network availability at an edge location, connect equipment to dual UPS systems, or build a more resilient server-rack power architecture, Hummingbird Networks can help identify transfer-switch solutions based on your electrical and equipment requirements.

Frequently Asked Questions About Transfer Switches

What is a transfer switch?

A transfer switch allows connected equipment to receive power from one of two compatible electrical sources.

What is an Automatic Transfer Switch?

An Automatic Transfer Switch monitors available power sources and automatically transfers connected equipment to an alternate source when the preferred source becomes unavailable or unsuitable.

What does ATS stand for?

ATS stands for Automatic Transfer Switch.

Why use an ATS in a server rack?

An ATS can provide redundant power-source options for single-corded servers, networking, storage, and other IT equipment.

What is the difference between an ATS and UPS?

A UPS provides battery backup. An ATS selects between two available power sources. They are frequently used together.

What is the difference between an ATS and PDU?

A standard PDU distributes power to multiple devices. An ATS transfers a load between primary and secondary sources. Some products combine both functions.

What is an ATS PDU?

An ATS PDU combines Automatic Transfer Switch functionality with multiple output receptacles for rack power distribution.

Can an ATS connect to two UPS systems?

Yes, compatible ATS products are commonly used with separate primary and secondary UPS systems to provide redundant UPS-backed power to single-corded equipment.

Can an ATS connect to utility and generator power?

Some ATS systems can operate with compatible utility, generator-backed, UPS, or other AC sources depending on the product architecture and electrical requirements.

How fast does an Automatic Transfer Switch switch sources?

Transfer time varies by model. Current Eaton Tripp Lite Series IT ATS products include models that transfer within a few milliseconds.

Will equipment reboot when an ATS changes sources?

Compatible IT equipment with power supplies capable of tolerating the ATS transfer interval can remain operating. Verify the transfer time and connected equipment specifications for the exact deployment.

What is primary power on an ATS?

The primary source is normally the preferred power input used during normal operation.

What is secondary power on an ATS?

The secondary source is an alternate power input that can support the load if the primary source becomes unavailable or unsuitable.

Does an ATS switch back to primary power automatically?

Many Automatic Transfer Switches can return to the preferred source after it becomes stable again. Exact transfer logic varies by model.

Does an ATS provide battery backup?

No. The ATS itself selects between available power sources. Battery backup requires a UPS or another battery-backed source.

Does an ATS provide surge protection?

Surge-protection capabilities vary by product. Automatic source switching should not be assumed to provide the same protection as a dedicated surge protector or UPS.

Do I need an ATS for a server with dual power supplies?

Not necessarily. A server with two independent power supplies can often connect each supply directly to a separate A/B power path.

When do I need an ATS?

An ATS is particularly useful when equipment has only one power input but needs access to two redundant upstream power sources.

Can an ATS power multiple devices?

ATS PDU models can provide multiple output receptacles for several devices as long as total connected load remains within supported electrical limits.

What voltage ATS do I need?

The ATS input voltage must match the available power sources, and the output voltage must match connected equipment. Common IT ATS environments include 120V, 208V, 230V, and 240V.

What is a 1U Automatic Transfer Switch?

A 1U ATS mounts in one horizontal rack unit and provides automatic power-source selection for compatible IT equipment.

What is a metered ATS?

A metered ATS combines source transfer with electrical-load information, such as current monitoring.

What is a monitored ATS?

A monitored ATS provides remote visibility into power-source status and other supported electrical conditions through network management.

What is a switched ATS?

A switched ATS combines automatic source transfer with remotely controllable output receptacles on supported models.

Can a switched ATS reboot equipment remotely?

Yes. Selected switched ATS products support remote outlet power cycling for connected equipment.

Can I monitor an ATS over the network?

Selected managed and monitored ATS systems include or support IP-based network management.

What are C13 and C19 ATS outlets?

C13 and C19 are IEC receptacle types commonly used with servers, network switches, storage systems, and other enterprise IT equipment.

Can an ATS use NEMA connections?

Yes. Current IT transfer switches include NEMA configurations such as 5-15, 5-20, L5-20, and L6-30 depending on voltage and amperage.

Can an ATS use IEC inputs?

Yes. Higher-voltage rack transfer switches commonly use IEC C20 inputs and C13 or C19 outputs.

Can an ATS use two power sources that are not synchronized?

Selected ATS designs support compatible sources regardless of phase angle. Verify the manufacturer specifications for the exact model.

Does APC make Automatic Transfer Switches?

Yes. APC offers NetShelter Rack Automatic Transfer Switches for compatible enterprise rack and data-center environments.

Does Eaton Tripp Lite Series make Automatic Transfer Switches?

Yes. Eaton Tripp Lite Series offers metered, monitored, and switched ATS PDU solutions across multiple voltage and current configurations.

Can an ATS help during UPS maintenance?

Yes, in appropriately designed redundant power architectures. Selected ATS products can support alternate power paths while an upstream UPS is serviced.

Does an ATS protect against a complete facility outage?

Only if an alternate source remains available. If both ATS input sources fail, the transfer switch has no source from which to power the connected equipment.

Can Hummingbird Networks help me choose an Automatic Transfer Switch?

Yes. Providing the equipment load, input voltage, amperage, primary and secondary power sources, required output receptacles, rack configuration, and management requirements can help identify appropriate ATS options.

Shop Automatic Transfer Switches

Improve power-path redundancy for servers, network switches, routers, firewalls, storage appliances, communications systems, and other single-corded IT equipment with Automatic Transfer Switches designed for business and enterprise infrastructure.

From APC NetShelter Rack Automatic Transfer Switches to Eaton Tripp Lite Series metered, monitored, and switched ATS PDUs, Hummingbird Networks can help organizations select transfer-switch solutions based on voltage, amperage, power-source architecture, equipment load, rack design, monitoring, and redundancy requirements.