Measurements in High-voltage Environments: Overhead Line and Pantograph Maintenance

A train’s catenary is a vital part of railway infrastructure. It can be seen as its circulatory system, feeding the rolling stock. The correct contact between the pantograph and the overhead line is mandatory for efficient train operation. Electric trains establish contact to the catenary via their pantographs.

The characteristics of high-voltage overhead contact lines for electric trains need to comply to certain criteria to ensure minimal losses, limited wear and tear, as well as a reduced risk of disruption during the current transmission to the power unit of the vehicle. To meet the requirements of these operational conditions, the catenary’s vertical and horizontal positioning and its tension both need to comply with international standards.

Monitoring Ensures Safe and Reliable Train Operation

Monitoring forces and accelerations under high voltage in the pantograph structures reduces the risk of possible damage to the catenary of railway networks.

Typical Applications

  • Predictive overhead line (OHL) maintenance – 24/7 overhead line monitoring through regular trains
  • Active control of the pantograph contact force – particularly important for high-speed applications
  • Homologation and testing of the pantograph (EN50317)

A reliable monitoring system delivers valuable information on the condition of the overhead contact line in combination with the position of trains along the track.

Measurements should include values such as vertical contact force, vertical acceleration, and sideway position calculation from contact forces.

Pantograph measurements and the evaluation of the catenary condition can be made with regular railway engines equipped with measurement systems during normal operation. The ability to record and collect all data in database enables the monitoring of specific locations over a chosen period, resulting in the acquisition of data for predictive overhead line monitoring.

But what are the requirements for a reliable monitoring system and a sustainable diagnosis?

Robust, Accurate and Stable: Optical Technology

The main requirement for overhead line and pantograph monitoring are accurate measurements within a high-voltage environment (15 – 25 kV). Optical sensors are passive elements, and as their measurement principle is based on light, no active excitation of the sensors is needed. That means that there are no interferences with other operations during measurement.

Optical technology is immune to EM and RF interferences, and is, therefore, the perfect fit for catenary and pantograph measurements. Where electrical sensors fail, or need advanced protection methods, optical measurements are still reliable, accurate and stable.

The focus of the measurements via a fiber optic sensing system is the lateral displacement of the overhead contact wire, the momentary vertical contact forces, and the detection of impermissible force peaks and loss of contact.

 

HBK’s Fiber Bragg Grating (FBG) Pantograph Measurement System ensures:

  • Detection of the contact force relief on the pantograph

  • Measurement of the side way movement of the contact wire

  • Detection of undesired peaks in contact force

  • The possibility of tracking all performed measurements via GPS location (1 m position accuracy)

  • Definition of thresholds and triggering of instantaneous alarms when a critical condition is detected

  • Continuous 24/7 operation

  • Compliance with EN 50317 (standard for measuring the pantograph contact line interaction)

  • Minimum influence in vehicle maintenance by using standard contact strips

 

Safe operation under high voltage environment

All components are passive under high voltage as the sensing elements are based on optical fiber.

Long-term reliability

Proven technology with long-term stability with acquisition of wavelengths using NIST traceable references.

Flexible hybrid solutions

The MXFS module is part of the popular QuantumX DAQ system, making it easy for you to integrate optical and electrical measurements into your measurement chain.

HBK Optical Pantograph and OHL Monitoring Solutions

The HBK fiber optic sensing system has been developed and is available to be used in regular, tested and certified pantograph models. It reliably fulfils the main requirements, such as the ability to measure with suitable accuracy in a high voltage environment (15 – 25 kV), to adequately locate and track the train position, and to record, merge and assess large quantities of data in compliance with the relevant sections of EN 50317.

The HBK optical measurement solution consists of the QuantumX MXFS BraggMETER, the newLight optical FBG Heavy Duty Force Transducer FS66HDL and Heavy-duty Accelerometer FS65HDA. Related accessories ensure the transition from the high voltage to the inside of the cars.

 

FS66HDL Heavy-duty Force Transducer

 

FS65HDA Heavy-duty Accelerometer

 

QuantumX MXFS BraggMETER

 

FS66HDL

FS65HDA

QuantumX MXFS Optical BraggMETER

New and unique development

  • newLight® technology
  • High resolution
  • Low weight, 99g
  • Compact design
 

New and unique development

  • newLight® technology
  • High resolution
  • Very low weight, 34g
  • Compact design
 

Optical interrogator for FBG (fiber bragg grating) sensors

  • 8 parallel optical connectors
  • 100 S/s and 2,000 S/s acquisition rate
 

Measurement range ± 500N

Measurement range ± 20g

Full integration with QuantumX platform

  • Small size and light weight for mobile applications
  • Robust design for intensive operation
 

Forces measured via shear beam principle

  • Temperature effects cancel out
 

Acceleration measured via seismic mass principle

  • Temperature effects cancel out
 

Proven continuous swept laser scanning technology

One connector housing for two optical fibers

  • Possibility to connect sensors in series
 

One connector housing for two optical fibers

  • Possibility to connect sensors in series
 

Continuous calibration with NIST traceable wavelength reference

  • Ensures system accuracy over long-term operation
 

Rugged

  • Protected and covered, weatherproof
  • Railway rated cables and connectors
 

Rugged

  • Protected and covered, weatherproof
  • Railway rated cables and connectors
 

High resolution

  • Assured by efficient peak detection algorithms
 
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