Fiber Service Units – C37.94 FSU E1- RFL

Model: C37.94 FSU E1- RFL

RFL offers two types Fiber Service Units (FSU) for substation or industrial applications, this includes one for protective re-laying that complies to the IEEE C37.94 standard and another for T1/E1 applications

The C37.94 units offer a multitude of electrical interfaces for diverse applications (X.21, V.35, RS-449, G.703 and E1) and are also available with non-standard single mode fiber options. The T1/E1 units can be used with multi-mode and single mode fiber over varying distances and are also compatible with the optics on IMUX 2000 multiplexers. Both standard units are designed for wall mounting, however, rack mount options are available for both FSU’s with 1RU (1.75") and 3RU (5.25") 19" rack mount chassis.


Low Cost Fiber

  • Low cost fiber solution for T1/E1 fiber extension or point-to-point long haul applications. Ability to add fiber connectivity to other manufacturer's multiplexers.

Multiple Fiber Interfaces

  • The RFL T1/E1 FSU can be configured with 1300nm multimode or singlemode LED emitters or 1300nm and 1550nm LASER singlemode emitters.

Long Transmission Distances

  • Depending on the fiber emitters used, T1 or E1 signals can be transmitted up to a maximum of 90 km (55.9 miles) based on typical loss calculations. All fiber options feature automatic gain adjust so the receiver cannot be saturated, meaning no attenuators are required.

Wide Range Supply

  • Wide Range 38-150 VDC Power Supply


  • Available for wall, 1RU x 19", or 3RU x 19" mount

C37.94 FSU

Low Cost Solution

  • Low cost solution to interface compliant Teleprotection equipment to existing non-compliant digital communication equipment

Multiple Electrical Interfaces

  • The RFL unit converts the optical signal into an electrical signal that will be accepted by the multiplexer. It is available with RS449, G.703, V.35, X.21 and E1 interfaces.

Multiple Transmission Speeds

  • The data is typically 64kb/s but the standard provides for speeds up to 768kb/s or (12 x 64 kb/s). The gross bit rate is 2.048 Mb/x and the frame complies with G.704 (E1) rules.

Wide Range Supply

  • Wide Range 38-150 VDC Power Supply


  • Available for wall, 1RU x 19", or 3RU x 19" mount
Operating Temperature: -20 C to +55 C
Operating Humidity: 90% RH Non-Condensing @ 40 C
Supply Voltage: 38 to 150 Vdc
Power Consumption: Less than 5W
ESD Withstand: ANSI C.37.90.3
RFI Withstand: ANSI C.37.90.2
SWC Withstand: ANSI C.37.90.1
Dielectric Withstand: 2500 VDC (Power and Alarm Inputs)