Static Transfer Switches
A static transfer switch (STS) uses solid-state thyristors to move a load between two independent power sources, typically two separate UPS outputs in a 2N system, within a quarter cycle, fast enough that connected equipment never sees the transfer. NLS sources STS units classified under IEC 62310-3 for Saudi data centre 2N architectures and hospital essential branches.
A 2N power architecture runs two entirely independent UPS systems, each capable of carrying the full load on its own, so a fault anywhere on one path, including the UPS itself, never touches the other. The gap that architecture has to close is the load side: most IT equipment and single-corded medical devices have one power cord, not two, so something has to pick which of the two independent sources actually feeds that single cord at any moment, and switch instantly if the active source fails.
That's the static transfer switch's job. Built around solid-state thyristors rather than a mechanical contactor, an STS can sense a fault on the active source and switch the load to the alternate source within a quarter cycle, under 5 milliseconds at 50Hz, fast enough that a server's power supply or a single-corded medical device rides through the transfer without so much as a flicker, let alone a reboot.
IEC 62310-3 classifies static transfer switches by their transfer characteristics, covering both the switching time and the output waveform continuity a unit maintains during a transfer. A mechanical transfer switch can achieve similar redundancy logic but takes tens of milliseconds to switch, acceptable for some loads but not for equipment sensitive enough to reboot on even a brief interruption.
NLS sources static transfer switches sized to the amperage and voltage of the two source paths a project specifies, for Saudi data centre 2N architectures at the rack or row level, and for hospital essential branches feeding single-corded critical equipment from dual independent sources.
Specifications
- ✓Switching technology: solid-state thyristors, no moving contacts, sub-quarter-cycle transfer time
- ✓Transfer time: under 5 milliseconds at 50Hz, fast enough to avoid a reboot on single-corded loads
- ✓Standards referenced: IEC 62310-3 classification for static transfer switches
- ✓Sources: switches between two independent power paths, typically two separate UPS outputs in a 2N system
- ✓Application: data centre 2N architectures at rack or row level, hospital single-corded critical equipment
- ✓Comparison: faster than a mechanical transfer switch, which typically takes tens of milliseconds
Frequently Asked Questions
How fast does a static transfer switch move a load between sources?+
Within a quarter cycle, under 5 milliseconds at 50Hz, using solid-state thyristors rather than a mechanical contact. That's fast enough that a server or single-corded medical device doesn't reboot during the transfer.
Why does a 2N data centre need static transfer switches?+
Because most IT equipment has a single power cord, something has to decide which of the two independent UPS paths feeds it and switch instantly if the active one fails. An STS does that switching fast enough to avoid an interruption.
Who supplies static transfer switches for Saudi projects?+
NLS sources static transfer switches sized to the amperage and voltage of the two source paths a project specifies, for data centre 2N architectures and hospital essential branches feeding single-corded critical equipment.