Cable monitoring devices can be as standard or with additional monitoring of the cable shield for breaks. Here we make use of a trick in that the measuring resistances lying parallel to the insulation section to be monitored are not built into the cable monitoring device but instead one of them is installed at the end of the cable to be monitored. In this way the measuring current flows through the cable shield and a break in the shield leads to a break in the measured current and can be evaluated accordingly.
Since the cables do not as a rule terminate in the switching cell, this often results in the question as to how these resistors can be installed suitably? Shrinking on the terminating resistor within the sleeve at the end of the cable is to reject because of problems of accessibility.
Working in collaboration with various railway operators, we therefore came up with three basic solutions for this problem: Installation of the terminating resistor in a housing that has a snap-type socket for mounting on the carrying rail. The resistor itself is encapsulated for protection against external influences. A further version was produced in the form of a housing for attachment to flat surfaces, housing walls, etc. A third alternative provides the same encapsulated module in a weatherproof housing with metric screw connection. Today there are the following corresponding versions of the solutions:
There are two versions with the same housing dimensions. This housing with a built-in resistance of 68 kOhm, 17 W, type 85319 x is available to monitor the cable shielding for breaks and to display this breakage as an »internal short circuit«.
The type 85329 x configuration takes into account the options of switching a terminating resistance of 1120 kOhm between the conductor and the shield. This version likewise offers the option to monitor the shield for breaks. In this case an shield break leads to a »Earth short circuit« display.
A stainless steel installation plate is also available to install this terminating resistor in a weatherproof housing (version type 853 x 98). This plate can be used either for attachment with M6 or M8 threaded bolts or else with strip-type fastening.
See the complete brochure folder for additional information and accessories.
Data sheet [PDF]
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