To assist trackside applications of Network Rail's preventative maintenance program, by monitoring currents in rail signalling problems.


Photo Credit: Peter Hellberg

Photo Credit: Peter Hellberg

How does it work?

 

The Nic (Non Intrusive Current Monitor) is used as part of the preventative maintenance systems on trackside applications. If the signal received from the Nic via the associated data logger to the programme output highlights the primary current variations are outside the normal limits, then it indicates there is a potential problem.

 

This is done when the cable carrying the current to be monitored is passed through the hole in the side of the case. Internally it passes through a current transducer which outputs a voltage to the rectifier stage. Following full wave rectification the signal passes through a low pass filter, the output of which connects to the 4 to 20mA current output stage. (Note the full way rectification only applies to units for bipolar primary input current)


Photo Credit: Mitya Ku

Photo Credit: Mitya Ku

Features & Benefits

Features:
•    Non-contact measurement of DC currents up to ±600mA.
•    4 to 20mA current output.
•    Current trip with relay output.
•    LED trip indicator.
•    24V DC power supply.
•    Supply Reverse Polarity protection.
•    DIN rail mounting.
•    Unipolar versions also available.

Benefits:
•    Enables significant reduction in manual routine inspection.
•    Ability to ‘fix before failure’.
•    Network Rail and SNCF approved.
•    Intelligent infrastructure initiative for remote condition monitoring and proactive maintenance.

 


Introducing the Split-Core NIC.

The Non Intrusive Current Monitor (NIC) is used in control monitoring systems, allowing rail engineers to "fix before failure".

Designed for trackside application to assist Network Rail’s preventative maintenance programme, the split-core NIC has many benefits, including its retro-fit installation. This allows the unit to be clamped around circuits without interference to the circuit or signalling systems and removes the need for costly downtime when a rail control monitoring system (RCM) is installed. This means that the rail network can continue to run safely while maintenance work is carried out.

The signal is received from the split-core NIC via the associated data logger, the programme output then highlights that the primary current variations are outside of the normal limits, indicating a potential problem.

The aperture can be opened and closed via a jaw latch locking system. The on-board green LED indicates the unit is powered up and the red LED indicates that the primary current has reached the defined trip level. This allows installation engineers to see real-time working functions. The transducer can be clamped around a conductor of sizes up to 26mm in diameter.

The transducer uses Fluxgate Sensing Technology which is a passive sensor that is far more sensitive than conventional magnetic sensors. Its other advantage is its superior performance at extreme temperature ranges, found in rail networks, as well as ambient temperatures. This results in a far greater overall accuracy of the RCM. The sensitivity combined with the temperature improvements gives a much improved measuring resolution.

The design team behind the split-core NIC were aware of existing problems caused by rail network AC electrical noise from overhead lines, which are picked up on DC trackside signalling circuits. The transducer was designed to remove these with low pass filtering techniques. 

Filtering is done at the source of the measuring circuit to completely remove the noise generated from the output signals.

Features & Benefits

  • No electrical disconnection of monitored equipment is required for installation / removal.
  • Designed to meet Network Rail and SNCF approval.
  • Ability for equipment to be "fixed before failure".
  • Intelligent infrastructure initiative for remote condition monitoring and proactive maintenance.
  • Does not require track possession to fit.
  • There is no disconnection required so does not require testing of the signal circuit.
  • The product is RoHS and WEEE Compliant.