Difference between ATS, STS, standby, online and line-interactive UPS

STS (Static Transfer Switch)

STS is used in two separate switch between AC power supply, the first road after the failure of STS automatically switch to the second road to the load power supply, the second the words of STS path failure automatically switches to the first road to the load power. With the traditional automatic transfer switch ATS is different from the static transfer switches to provide fast load switching (typically 1 / 4 cycle), sophisticated electronic equipment to ensure uninterrupted work. Load re-conversion to the main input power is actually instantaneous (≤ 8ms). Suitable for UPS and the UPS, UPS and generators, UPS and the city, electricity, electricity and the electricity power supply such as an arbitrary two-way conversion UPS.

STS Static Transfer Switch mainly by the smart control panel, high-speed silicon, circuit breakers pose. The standard switching time is ≤ 8ms, will not cause IT class load power. Both on the load reliable power supply, while ensuring STS-phase switching in different security. STS Basic applications include electric power industry automation systems, petrochemical industry, power systems, computer and telecommunications centers, building automation and security systems, and other sensitive equipment against power failure.

ATS (Automatic Transfer Switch)

ATS is mainly used in emergency power supply system, will automatically load circuits from a power supply for access to another (standby) power supply switching equipment to ensure that critical load of a continuous, reliable operation. ATS mechanical structure to the implementation of contactors for switching components, switching function of intermediate relay or logic control modules to complete the secondary circuit control functions, drawback is that the main circuit contactor needs to loop a long-term secondary power, prone to temperature heating , contact bonding, coil burning and other failures. Furthermore, if a big load, the conversion time is relatively long, more than 100 milliseconds will cause the load power.

Standby vs. Online UPS vs. Line-interactive UPS

Standby and line-interactive UPSs turn on the inverter when the power fails and can only provide short periods of battery runtime (by design). This leads to an interruption (transfer time) when the inverter power takes over. Also, during normal operation, they leave equipment connected directly to the utility with very limited protection from common power disturbances. This may be acceptable for non-critical devices, but it has a risk factor. If an application can’t afford risks, the right solution is an online UPS.

While both online and line-interactive types of UPS provide full protection from major power problems, such as surges, spikes, sags, blackouts and brownouts, they differ in a few significant areas. Simply put, an on-line UPS offers a higher level of protection than a line interactive at a higher cost. More specific areas where the two types differ include sine wave output, voltage regulation, and double-conversion inversion.

While an online UPS is the top of the line protection available, it can be costly. These units are best suited for sensitive mission-critical equipment that handles very sizable amounts of power. Many people are looking for great protection that won’t hurt the budget too much, which is where the line interactive units come into play. Line interactive UPSs are a great balance between protection and quality, typically ranging from 500VA to 3000VA to ensure the right fit for every system.


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