Signal Relay FSU K- 50

The relay FSU K-50 enables correct functioning of all the elements of electric circuit with high standards defined in relay reliability. The relay FSU K-50 is commonly used for the installation in relay groups, providing functionality of the device SpDrS-64-JŽ. The signal relay K-50, which has maximum 8 contacts (mostly 4 working and 4 break contacts), is installed in station groups, APB groups and station groups for level crossings. The Q relay (with improved characteristics) is installed in signal groups, station cabinet and station signal groups. The relay FSU K-50, a product with exceptional design and functional reliability, emerged based on longterm experience and constant development.


Excitation side:

  • Current type: direct
  • Nominal voltage: from 60 V.D.C.
  • Excitation power: approximately 1,3 W
  • Work power: approximately 2 W
  • Time of attracting contacts: 25 – 60 ms.
  • Time of releasing contacts: 7 – 15 ms.
  • Thermal permanent load: 4,5 W
  • Test voltage: coil/body 2000 V.A.C.
  • Number of coils: max 2

Contact side:

  • Every contact consists of 2 serial contact places
  • Voltage interruption on contact: max 250 V.A.C.
  • Pressure power by contact: ≥ 0,15 N
  • Material for contact: silver
  • Permanent current of closed contact: 5A

The weight of the relay is approximately 220g. Its position during assembly is horizontal. Allowed tilt is 45⁰ in all directions.


Supporting relay is used in relay safety circuits for interlocking and blocking (driving route, interstitial signal approval), so as to remain in the position required until new request for position change. Supporting relay consists of two normal relays FSU K-50 whose anchors are mechanically coupled. The relay with anchored armature remains mechanically locked with the anchor of the released relay. This relay belongs to bi-stable relays (stable in two positions depending on the excitation, one or the other relay K-50). It has two coils and two anchors, being each one with it’s own contact system.