Auto Transfer Switch




UPS mains switch, Dual input backup switch, UPS power switch.


What is an ATS / Transfer switch?

An Automatic Transfer Switch is an electrical (Electro-mechanical or electronic) switch which sits between various power supplies (either mains, UPS, Solar, etc.) and the equipment being powered. Switches featured on this website are primarily concerned with the supply of power to IT equipment - electronic Network equipment such as servers, routers, hubs etc. but can be used for other applications.


Visit our Product Selector guide to find the best transfer switch for your needs.




16 amp ATS - Suitable for power ranges from 3Amps up to 16Amps


32 amp ATS - Suitable for power ranges from 5Amps up to 32Amps






ATS Diagram








Typically network devices in Datacentres (Data Centres or Datacenters) are powered directly by mains electricity, but have a UPS (Uninterruptable Power Supply) installed as a backup power source. A UPS will support the operation of equipment for some time (the amount of time will be dependant on the capacities of the UPS batteries in relation to the current drawn by the connected equipment) which will either support the IT equipment until the mains power becomes available again, or until the staff supervising the IT installation are able to close down the equipment in a structured way.


In addition, some IT sites have backup generators installed. Switching between Mains/UPS/Generator Power can also be accomplished by an ATS or a series of ATS devices.

An ATS can safely switch from mains to backup generator as a temporary source of electric power, and can also be used to start Generators when mains power is showing signs of faltering, so that the Generator is up and running before switching is necessary.


An ATS continuously monitors both the Primary electrical input feed (normally mains power) and the Secondary electrical input feed and makes decisions based on the relative quality (it looks for voltage drops, spikes or surges etc.) of each input as to which feed to use.


ATS input


An ATS can be configured to provide power to the most critical servers only, and to allow other less important IT processes to close down so as to maximise available UPS power in the way most beneficial to the overall operation.

ATSs can incorporate Power Distribution via multiple IEC C13 or C19 sockets, or can simply operate at main supply level and switch IEC 309 (Commando) or Nema sockets feeding separate PDU systems.


An ATS used in conjunction with Power Sequencer (Power sequencing) PDUs can handle completely automated shut-down and start-up of facilities so that where power outages occur, the IT installation is closed safely and as clean mains power becomes available again restored, in a correct and safe manner.



16 amp ATS - Suitable for power ranges from 3Amps up to 16Amps


32 amp ATS - Suitable for power ranges from 5Amps up to 32Amps



Basic ATS 


basic ATS


Basic Automatic Transfer Switches are available (230v) in 10 Amp, 16 Amp or 32 Amp versions and (110v) in 10 Amp, 15Amp or 30 Amp versions. They all serve the same purpose, and behave in similar ways. They will simply monitor the power from each alternative feed and switch the input source whenever necessary to use the best available power feed. The status of the live/standby feeds is indicted on the switch by LEDs.



Managed (IP Metered) ATS


ip ats 1



Metered, managed Transfer Switches work in exactly the same way as basic ATSs but can be set-up and managed remotely from anywhere in the world over IP. Upon switching, or upon pre-set power supply degradation levels a managed ATS will of course do its job and switch source appropriately, but will also send power deterioration reports (so that supply problems can be investigated and sorted before the situation becomes critical and switching is necessary) and will generate alarms by email and via SNMP. Managed ATSs feature a true RMS Current Meter, and reports and logs Voltage, Frequency, Power Factor, Active Power, Apparent Power, Total kWh and Sub-total kWh. These readings are displayed locally on a bright LCD display and remotely on any logged-in PC. Remote access is password protected for security, and data is encrypted to the SSL standard. Managed ATSs can also support and optional Temperature and Humidity sensor, so that the operating environment can be monitored and controlled.



ip ats 2


No software is necessary to set-up or operate a Managed ATS, it has its own built-in web page making it very simple and straightforward to configure and use. Managed ATSs integrate easily with any mainstream Network Management, DCIM or similar package which is SNMP compatible, and also support Http, Https, DHCP and UDP.