To provide uninterrupted server room load in the event of power outage, a Static Transfer Switch (STS) is a Static Electric device that automatically transfers load from preferred power source to standby power source linked to its input in the event of power outage and vice versa. It is, as the name implies, a completely static gadget with no moving parts. In the datacenter, a Static Switch can assure continuous power supply by transferring load in a fraction of a cycle time. Antiparallel thyristors are connected in each phase of the Static Transfer Switch.
Thyristors that may be turned on and off by a Gate Signal of Negative polarity are known as Gate turn-off Thyristors (GTO). Faster load transfer is achieved by managing the on/off switching of these SCR. Assuming that a disturbance in one source is noticed, and then a load is transferred to another source, the total amount of time required for transfer is calculated. The schematic for a static transfer switch is illustrated above. It has its own input MCCB and maintenance bypass switch on the thyristor circuit of both sources.
Control logic, metering circuit, Thyristor circuit, breaker, and Bus assembly make up the Static Transfer Switch. Logic controls the flow of current and voltage from both sources to the rectifiers by continuously monitoring the current and voltage. The voltage and current of the prepared source and the alternate source are constantly monitored by control logic. For example, if a preferred power source fails or if there are disturbances like over/under voltage and current, then control logic examines the status of an alternate power source and transfers the load to that source. Automatic transmission can occur in as little as 6 milliseconds if the phase errors of both sources are kept to a minimum.
In general, there are two kinds of static transfer switches. Single-phase and three-phase STS are the two types of systems. From 16A to 160A, rack-mounted units are available in this range. There are two types of three-phase static switches: those with three poles and those with four. In a three-pole S T S system, the neutral wire runs the length of the system. Both input sources and input neutral are connected directly to output neutral in other words.
Static transfer switches have the following benefits:
In other words, it's more dependable because of the higher level of quality it provides. It allows for the quick movement of weight. Only a few milliseconds are needed to transport a load. Additional safeguards include a transient voltage surge suppressor built in. The voltage limit can be set to protect the load from sags, swells, and interruptions, depending on the user's needs. Static transfer switch monitoring is accomplished via a dry contact.