Generator System Upgrade

The challenge

  • Several operational problems of the system; occasionally generators were starting without any blackout and even worse sometimes the generators were not starting at all after a blackout.
  • Poor control of produced voltage and frequency. Lack of load sharing between the two generator sets.
  • No capability of adding a new generator which could load share with the installed ones.
  • Control cards were based only on analogue control. Furthermore most of them had become obsolete during the years of operation.
  • Lack of any system which could control the sub-loads of the hospital in the case of generators overload.
  • Lack of any data recording system; no investigation of any incident could be executed.
  • Inadequate monitoring and alarms annunciation.

MAS solution

  • Installation of sophisticated Woodward diesel generators controllers. Initially for the two existing generators and for one additional generator installed at a second phase.
  • Replacement of old style relay automation with modern plc system responsible for the transitions from mains to emergency bus and vice versa. Data and alarm logging were also included.
  • Installation of a sub-load system rejection; in the case of generator’s overloading the system rejects non-essential consumers in order to reduce the power demand and limit it at the generator’s full load rating.
  • Installation of high-accuracy network analyzers at all main substations of the hospital.
  • HMI (Scada) installation for remote monitoring and logging. Communication with diesel generator controllers, plc and network analyzers is implemented through Modbus protocol. All related information is presented with graphical and user-friendly way. Remote access (with security levels) from several computers belonging in the hospital’s network was also fulfilled.


  • High availability of the emergency diesel generators system due to modern sophisticated control units that were used.
  • Precise control of generators’ voltage and frequency. Improved control of transient load demand.
  • Capability of adding 1 or more new diesel generators which can run in parallel with the current installed units.
  • Improved system’s stability due to the existence of sub-load rejection in case of generator’s overload.
  • Electrical data monitoring and recording of the whole emergency electrical system.
  • User friendly HMI application with remote access to over 6 working stations in the hospital.