Static Transfer Switch

The TECNED ST-D Static Transfer Switch series is available with single phase input /output 220/230 or 240Vac and current ratings from 25A to 500A.

The ST-D series can be supplied as a 1-pole or 2-pole static switch to meet customer requirements for safety and reliability. Standard features include input V metering, mains S1-S2 out of tolerance alarm and general alarm with potential free contacts and input/output fuse monitoring.

The ST-D includes a digital controller with LCD display that shows the systems current state of operation and system values, allows setting of system parameters and includes event and alarm logs.

Option list ST-D

  • Extend to 12x PFC (NO/NC) with LED
  • Individual fuse failure indicator
  • Fan failure alarm
  • 3-position mechanical bypass
  • Over temperature
    Up to 6 (DIN 96) meters / cabinet


InputVoltage2x 220/230/240 V + N
Voltage tolerance180 / 264 Vac (Ph-N)
Frequency50Hz / 60Hz
Frequency window2-10% adjustable
Slew rate1-4Hz/sec (selectable)
OutputTransfer typeBreak before make
Transfer methodsAutomatic / Manual / Remote
Transfer time< 4 msec (S1-S2 synchronized)
 < 10 msec (S1-S2 not synchronized)
Overload150% for 1 min. / 200% 10 seconds
Power Factor0.6 lag to 0.9 lead
GeneralAmbient temperature-20 to +70 °C storage / -10 to +40 °C operation
Altitude above sea level1000 m
EnclosureAluzinc frame / powder coat RAL 7035
StandardsSafety IEC/EN 62040-1 / EMC 55011
ConformityIEC 60146 / CE-Label