The GCU unit is designed for Observation the Mains supply and control the Generator unit to reduce the Electric power failure condition. It will continue the supply to load either by Mains or by Generator unit (When mains is not available or out of range)

 The GCU has the easy operation in any condition Auto/ Manual. In auto mode it monitors the mains condition Normal / Abnormal and then switch ON / OFF the mains on load. In absence of Main supply or abnormality it checks the Generator condition and switch on the generator then monitor the generator supply as Voltage / Frequency and connect the load. Meanwhile if Mains comes the Load will transfer to the Mains immediately & Generator will be running on for 2 minutes on no load to reduce its temperature. It will give alarm on any abnormality or failure condition either in Mains or in Generator.


     GCU Panel

        GCU Panel



GCU has following features :

  • Generator start at mains abnormal or failure
  • Selection of the standby generator when main generator fails.
  • Automatic load transfer on generator from mains AC and vice versa.
  • Tripping of DG at resumption of AC mains & at any abnormal condition of DG Low fuel level larm
  • Audible indications at any abnormal condition.
  • Electronic interlocking of the generator supply and the AC mains supply.
  • Bypass facility for manual operations of DG set.
  • All timers are site programmable
  • Measurement of temperature, pressure and speed of generator
  • Industrial safety standards are duly adhered


It sense also battery voltage, it will start the Genset whenever battery voltage cross beyond the discharging limit voltage (43V adjustable) at the time of mains failure.


  1.     Mains fail
  2.     LLOP
  3.     High cylinder / water temperature
  4.     Over speed
  5.     Under speed
  6.     Alternator fault
  7.     DG fail to start
  8.     DG fail to stop
  9.     Overload
  10.     Fuel low
  11.     Fuel very low (for stopping of engine)
  12.     BTS battery low
  13.     DG battery low
  14.     DG fault (common for any DG fault)
  15.     Canopy door open
  16.     Fire Alarm
  17.     Canopy temperature high
  18.     Low water level (for water cooled sets)
  19.     Over / Under voltage
  20.     Over / Under frequency


  • AC mains and DG supply
  • System working mode i.e. Auto or Manual
  • Engine speed
  • Oil pressure
  • Coolant temperature
  • Fuel level
  • KVA/Kwatt /PF/Current


  • LLOP
  • DG on
  • DG battery low
  • DG fuel low
  • Under speed / Over speed
  • Stop fault
  • Start fault
  • Engine Temperature high
  • Alternator fault
  • BTS battery low
  • Mains ok / mains faulty
  • Overload
  • Over / under voltage
  • Canopy temperature high
  • INSTALLATION: – Its installation should be done by qualified person. GCU Unit is supplied with manual and Guideline book.