Humber Bridge – U.K.


How The World’s 7th Largest Suspension Bridge Battles Voltage Fluctuations

Case Study For Humber Bridge U.K.

Spanning 2.22km long and carrying an average of 120,000 vehicles per week, the Humber Bridge in Yorkshire, England, is the seventh-largest suspension bridge in the world.


In efforts to prolong an achievable design life of the suspension cables, engineers of the Humber Bridge installed state-of-the-art dehumidification systems. 


To do that, they’ll need additional electrical power, which involves the running of long supply cables from both sides of the bridge.



The Problem:
Severe Voltage Fluctuations From Seismic Shock

For optimal performance of the dehumidifiers, it was absolutely imperative to ensure stability and quality of the incoming power supply at 415V.


Having worked on other suspension bridges in the U.K., engineers from Electrical Contractor, Pennine Control Systems knew all too well about the flexural and torsional vibration effects on voltage stabilisation equipment.


The challenges faced:

  • Inherent voltage drop from long cable runs
  • Incoming voltage values could possibly drop to as low as 356V
  • Heavy voltage fluctuations caused by constant load change
  • Load change was due to continuous vehicular movement on the road decks 
  • Total power rating requirements of up to 420 KVA.


Based on past experiences, it was clearly shown that previously used voltage stabiliser UK systems had not proven themselves sufficient to cope with strict requirements.


To overcome these obstacles, the team at Humber Bridge was in search of an omni-voltage optimising solution – one that could reliably solve these challenges


The Ashley Edison (UK) Solution

In 2010, Ashley Edison delivered a fully customised voltage solution to effectively accommodate the suspension bridge – meeting precise electrical and physical requirements.


The installations included the following series of Rack Mounted Servo-Electronic Automatic Voltage Stabilizers:

  • Servo Electronic Digitally Enhanced Design (Servo AVR)
  • Stepless Voltage Regulation at 415V (± 0.5% output voltage accuracy)
  • Wide input voltage tolerancestabilising a voltage swing from 340V up to 477V.
  • Forced-Air Cooling for improved operational efficiency
  • Fast Response Time (<1.5ms)
  • Inbuilt High Overload Capability (10x max current rating for 2 seconds)
  • Independent Phase Balancing & Control: Automatic voltage sensing & precise regulation to ensure individual phase voltages remain stable – from no load to full load.
  • Class II SPD – Lightning Surge Protection
  • Rack Mounted Enclosure
  • AquaStop – Protective PCB coating against moisture ingress
  • Transient Voltage Surge Protection (TVSS) protects critical loads against harmful high energy surges, transients and spikes.


The Complete Solution comprises the following:

  • Automatic Voltage Stabilisers (Model: SES Series)
    • 75 KVA x 4 units
    • 60 KVA x 2 units




The Result

This implemented solution successfully unlocks the desired operational outcome in the bridge’s dehumidification systems, enabling the load to enjoy constant and stabilised incoming voltages – regardless of load change or unbalance.


The Humber Bridge upgrading project was completed 1 year ahead of schedule, achieving optimised operational efficiency ever since.


Today, all 6 units of Automatic Voltage Stabilisers still prove to be a success in not only preserving but revitalizing the significance and heritage of a 40-year-old landmark in the U.K.

To learn more about voltage optimisation for bridge and tunnel applications, drop us an email at [email protected].


For more case studies on how other Governments have also adopted these advanced voltage regulating technology, read about their projects here.




Humber Bridge U.K.
AVR | 75KVA & 60KVA
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