STS SERIES (800-4,500A)

  • Continuous monitoring of sources
  • Automatic instantaneous transfer
  • Manual transfer capability
  • Redundancy of internal power distribution
  • Dual maintenance manual by-pass
  • Enhanced monitoring and diagnostics
  • RS232 and RS485 interface
  • System graphic control panel
  • Alarm, data history and event logs
  • Mimic panel with LEDs and audible alarm
  • Metering: kW, kVA, CF, PF, Current, voltage and frequency
  • Compact size
  • True over-sized neutral (2 In)
  • Short circuit transfer inhibit
  • Programmable alarm relay contacts
  • Front access to all power components
  • Bottom or top cable entry
  • Redundant cooling with monitored fans

STS Series

Static Transfer Switch

800A – 4500A

The EPI Static Transfer Switch is a solid state three phase STS designed to connect a critical loads to one of two separate sources of power, to assure supply continuity. The source to which the load is normally connected is designated as priority source and the other as alternative source.

EPI STS is fitted with two internal maintenance by-pass switches, which enable a load transfer to the supply sources without causing a power interruption to the critical load. Bypass isolation is complete, allowing all serviceable components to be maintained in safety. EPI switches between different AC inputs lines according to priority criteria and technical characteristics of the input voltages. If the lines are synchronized, the transfer time from one source to the other is less than 4 ms.

A clever key-operating interlocks ensures that the two bypass switches (one for each line) cannot be simultaneously closed, thus avoiding the direct connection of the two sources. The control logic ensures that in the event of an accidental closure of the bypass on the passive line, the EPI STS will automatically transfer the load on the line should the bypass operation has been carried on. The layout is designed for maintenance and service for the active components from the front.


  • 3-phase 4-pole configuration plug-in circuit breakers operation without neutral.
  • Output distribution panels
  • Isolation transformer
  • Special IP rating
  • Paint finish