Mechanical Governor Overhaul or Upgrade? Legacy Control Systems One Hundred Years Later

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Mechanical Governor Overhaul or Upgrade? Legacy Control Systems One Hundred Years Later


April 12, 2021


Roger Clarke-Johnson, Hydro Business Development Manager, Emerson


Mechanical Governor Overhaul or Upgrade? Legacy Control Systems One Hundred Years Later

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Mechanical governors have been the stalwart hydroelectric control system for over a century. The reliability and longevity of these governors has inspired confidence in generations of hydro maintenance crews. Literally thousands of them remain in service today around the world.  

Governors built in the early 1900s can meet the vigorous regulations of today, even as governor technology has long since moved into the digital age. As the years go on, hydroelectric project owners often wonder: Should I maintain my existing governors or upgrade them? 

Through most of the 20th century, governor upgrades were low on most owners’ priority list. The original equipment governors worked well and were extremely reliable. Maintenance crews understood how they worked and knew how to service them. Spare parts were either on-hand or readily availableand the major original equipment manufacturers (OEMs) continued to provide good support. There was no reason to upgrade. 

By the year 2000, all that changed. Governor-only OEMs had either gone out of business or been acquired by other firms. Parts were increasingly expensive and lead times were long. Powerplant crews found creative ways to get parts — they bought them locally, borrowed from other plants, or simply made the parts themselves. With little to be gained in terms of unit efficiency and concerns about computer technology, digital upgrades remained a low priority. 

Yet, governor technology had long since evolved into digital control, and governor OEMs made a business decision to cut off support for their legacy governors. When customers requested parts, they were told that their governors were obsolete and, although some parts were still available, support would end. Plants were encouraged to begin planning for digital upgrades, sending a shock wave through the hydro industry. 

Today, there are myriad options available for owners of ‘orphaned’ governors. Parts, service and training are available from non-OEM providers, and digital upgrades are no longer mandatory. With the immediate urgency of “no support available” removed, owners and operators can make a reasoned decision whether or not to upgrade their governors. 

Reasons to Upgrade to Digital Controls: 

  1. Relicensing-driven control upgrades 
  2. Market-driven enhancements 
  3. Personnel-driven operations changes 

Reasons to Maintain Your Legacy Controls: 

  1. Parts and repair services are available. 
  2. Tailored training is available. 
  3. Readily available retrofit kits improve performance. 
  4. Product life cycle of digital products is short.  

Emerson has a comprehensive portfolio of support for legacy mechanical and new digital governors alikeLearn more and make the best-informed decision with our Governor Decision Matrix. Request a copy today from our Hydro team to get started here.