Published date:

GrayBar Self Regulating Points Heating for use on High Speed Points PA05/688

Many of the high-speed points installed on the UK’s railways require an effective heating area of each rail up to 20 metres in length to meet performance and requirements.

The Challenge:

Constant wattage heater strips are only manufactured in short lengths, and therefore require multiple strips (typically 16), multiple trackside transformers, associated cables and trackside connection boxes to sufficiently heat a single set of high-speed points.

The Solution:

GrayBar Self-regulating heater elements can be manufactured up to 22 metres in one single heater strip, allowing the installation of 8 longer lengths of self-regulating heater strips per high-speed point. Each Point End would be powered by two 5Kva transformers (055/020886) mounted inside the control cubicle.

Reducing the amount of associated cabling and trackside connections to two 8 core cables and a single 16 Way trackside junction box, results in a simplified installation, reducing installation time and costs.

GrayBar self-regulating heaters are flexible and can be coiled up for easy storage and transportation. Unlike constant wattage heaters, transportation of multiple heaters to site can be achieved by a single small van vehicle, and transporting to track can be safely achieved with a single operative per heater.

GrayBar heaters do not contain a filament and have a positive increasing resistance when exposed to an increasing temperature, therefore cannot overheat and burnout, this gives GrayBar heaters a reliable service life in excess of 30 years. No fragile ‘hot ‘or ‘cold’ rail probes are required, these are a common cause of failure; GrayBar heaters regulate the power output in response to temperature changes in the rail all along its length.

Self-regulating heater controls, contactors etc do not switch ‘on ‘and ‘off ’in frequent cycles, and at lower power ratings than other systems therefore extending components lifecycles.

Technical Details:

The heaters are fed 110v ac from transformers mounted inside the control cubicle, negating the requirement for trackside transformers, reducing the size of the system footprint and distribution of higher voltage cabling.

For high speed GV type points, GrayBar’s 3 phase 400v control cubicle (PA05/688) is required. The 5Kva isolating transformers (PA055/020866) have 2 secondary 2.5 KVA windings and comply to BS EN IEC 61588 and NR/L2/ELP/40045.

Front & rear view of the PHCC

The main incoming supply will be fitted with an isolator switch rated to 160A ac also to comply with BS7671 and NR/L2/ELP/40045.

GrayBar control cubicles are fitted with a soft start facility to energise the transformers in timed increments, reducing the inrush currents on the phases when the system has called for heat. The inrush to the heaters is 4 times the steady state current in compliance with NR/L2/ELP/40045.

Activation of the cubicle is achieved with on board ambient temperature probes and precipitation sensors.

An 8 Transformer cubicle has the capacity to feed 2-point ends, 8 x 10 and 8 x 9 metre heaters PA-5/688, complete with protective heat shields PADS 055/021046 and 055/021053 to ensure efficient heat injection into the foot of the rail.

Each cubicle can have a datalogger installed, typically MPEC SA380TX, PA 05/03249 which will perform remote condition monitoring. The datalogger will detect and record the control panel contactors, relay states and condition of power supply. Electrical power consumption of the cubicle and the current draw of each individual heat will be recorded and can be accessed in real-time, informing the user of functional failures and warn of possible future malfunctions of the heating system. The system can be interrogated remotely or by using the datalogger integral touch screen at the cubicle side.

Communication to the logger is achieved via Ethernet or GSM/GPRS and data can be accessed via the industry approved Centrix diagnostics platform (access licence required), each unit is compatible with Network Rail’s MIMOSA XML protocol. Each unit comes with extended working temperature range and an integrated UPS.

The cubicle can also be equipped with Insulation monitoring devices, MPEC SA380-IT, PA 05/6393 for detecting first fault in IT systems (Outgoing heaters circuit) in accordance BS7671, NR/L2/ELP/40045

These devices will be networked into the SA380 TX datalogger units but have the capability to standalone with separate ethernet and GSM/GPRS communication.

Realtime data can be accessed via The Centrix server, or the devices are compatible with Network Rail’s MIMOSA XML protocol. Data can be accessed cubicle side via integrated Bluetooth.

Automated alarm settings in Centrix can be enabled to send alerts when anomalies are captured in the data.


Typical Requirements for GrayBar Self Regulating Points heating system for 1 GV type point end:

  • 1 x PHCC (4TF) 400V 3 Phase, complete with RCM and IMDs (GrayBar’s System can accommodate up to 2 Point Ends per Cubicle 8TFs)
  • 1 x Self-regulating Heater Kits for GV type Points (4 x 10m. 4 x 9m)
  • 1 x 16 Way Trackside Post Mounted Junction Box.
  • 2 x 8 Core Points Heating Cables cut in lengths to suit

Contact us today to discuss your requirements:

Tel: 01933 676700

E-mail: [email protected] or [email protected]