Static Transfer Switch

STS Series-Static Transfer Switch (50-1250A)


EPI STS, allows instantaneous transfer of power sources to the load. If one power source fails, the STS switches to the back-up power source so fast that the load never recognizes the transfer made.

Operating principle:
EPI STS guarantees a source of redundant power, allowing the load to be switched between to alternative and independent power sources. Switching can be automatic (when a supply source falls outside of acceptable tolerances) or manually done by an operator from the front panel or remotely.

Protection against environmental disturbances:
Overloads and load faults. In the event of an overload, the user can decide the level of intervention of the internal protection devices in order to block the power supply. In the extreme case of a downstream short circuit, EPI STS disconnects the load in order to avoid jeopardizing the operation of the other loads (i.e. in the event of poor selectivity of the protection devices)

Total microprocessor control:
Microprocessor control logic ensures:

  • Fast and safe switching between power sources
  • Monitoring of all parameters via LCD display
  • Constant monitoring of SCR operation
  • Advanced remote diagnostics (RS232 and TCP/IP)

Protection against power supply faults:
If one of the two power sources falls outside tolerance levels, EPI STS will transfer the consumers to the second power source (switching is instantaneous if the two sources are in phase).

Superior protection:
In the event of an output short circuit, EPI STS blocks the transfer between the two power sources, eliminating the risk of propagating the short circuit and its effects to the other loads. A back feed control circuit will trigger automatic protection devices to avoid energy feeding back to one of the inputs.

The layout of the moving components and parts is designed to ensure easy frontal access:

  • Power cable connections that are easily accessed with entry from below
  • Boards housed in a dedicated area for rapid diagnosis / replacement
  • All parts subject to monitoring, maintenance and/or replacement.


  • Increased power quality and noise reduction
  • Power blackout protection and power redundancy
  • Automatic static switching
  • Remote monitoring input power sources
  • Easy static and mechanical transfer to input sources
  • Remote management the power events
  • Power event logging
  • Output current capability up to 1000% for short time
  • Manufactured according to EC Directive; EN62310

STS Series-Static Transfer Switch (50-1250A)