Maintaining hydroelectric power plants requires special skills not typically found in most electrical maintenance firms or electrical contractors.  Many hydro power plants are over 100 years old with obsolete instruments and equipment and hence difficult to maintain.  In addition, if your Hydro power plant is like most, regulatory demands are rising, staff levels falling, maintaining the system is getting more complex, and your most experienced staff is retiring.  In addition, you want your plant to operate 24hours a day.

What are the best practices?

Electrical Systems Maintenance

Hydroelectric plant managers are tasked with keeping the electrical apparatus safe and reliable.  According to a 2014 study “Statistical Failure of European Substation Transformers” November 2014, the average failure rate of transformers is about 1 in 200 per year.  According to a 2005 study of breakers by the Army Corps of Engineers about one in 100 breakers fail per year.  See table 1.

To avoid unexpected or catastrophic failures, best practices for electrical maintenance are available in the International Electrical Testing Association publication called ANSI/NETA Standard for

Maintenance Testing Specifications for Electrical Power Equipment and Systems.   Contact a NETA firm that specializes on Hydroelectric apparatus such as UIS.


The wear of mechanical and electrical hydro apparatus will diminish the performance of the hydroelectric plant and run-of-river stability.  The main reasons to do calibration are:

  1. Accurate Management, NERC, and FERC Reports
  2. Process Optimization
  3. Asset Management Planning to help justify infrastructure upgrades

In 2022, UIS calibrated 3,204 instruments and found 5.3% were out of calibration or defective.  See the historical table. Since most calibrations are done annually, after one year, on average, 1 out of 20 instruments is not reporting accurately.  When were calibrations last done at your plant?  Table 2 is the recommended best practices for Hydroelectric instruments.


UIS Renewable Power works in all of North America as an integrator that specializes in Hydroelectric Controls for upgrades, electrical maintenance, and NERC and FERC compliance.  Contact UIS Renewable Power for all your future control upgrades or maintenance.