Design of an 10 kVA–45 A automatic static transfer switch module

Uninterruptible Power Supplies (UPS´s) are designed to provide emergency power when the main power source fails. To avoid this impact and to protect effectively the loads, one solution is to provide a redundant loading system using a dual power energy source other than the UPS to achieve an automatic static transfer when necessary. In this work, an additional module has been designed and connected between a critical load and the output of two independent UPS systems; if primary UPS fails, the module automatically transfers the load to the other one with a minimum transfer switching time. The results presented demonstrate a transfer switch time below 3 ms, compared to commercial products of 4 to 6 ms.