Product Catalogue

4200 Alarm Circuit Unit

The 4200 Alarm Circuit Unit (ACU) uses one slot in the 4200 MS and can be ordered pre-installed or can be installed in the field. This card allows the user to monitor a metallic sheath, twisted pair or metallic strength member for resistive faults to ground and splice closures for moisture ingress.


Digital Signal Processing is used for accurate sensor decoding and sensor measurements. One 4200 ACU is capable of monitoring up to 75 linear sheath miles (125 km) of fiber optic cable. Up to four 4200 ACU may be installed in the 4200 MS allowing up to four cables to be monitored by one 4200 MS. Monitoring with a 4200 ACU is complete when it is used in conjunction with 1107 SSU and 2230 STU. Using an ACU to monitor and maintain sheath integrity will guarantee good cable locates when required. The output of the 4200 ACU is negative 48 volts DC providing cathodic protection levels for most applications.



  • User Programmable alarm levels
  • Monitors up to 75 linear sheath miles (125 km)
  • Decodes and displays sensor codes
  • Computes and displays fault current
  • Cathodically protects armor


9 x 2.5 1.5 in (22.9 x 6.4 x 3.8 cm)
0.25 lbs (0.11 kg)