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Generator Control Units (GCU)

Generator Control Units (GCU) 

⇒⇒The Basic Functions of a Generator Control Unit (GCU) 
The generator control unit (GCU) is more commonly found on turbine power aircraft. The most basic GCU performs a number of functions related to the regulation, sensing, and protection of the DC generation system. 

  • Voltage Regulation 
most basic of the GCU functions is that of voltage regulation. Regulation of any kind requires the regulation unit to take a sample of output and to compare that sample with a controlled reference. If the sample taken falls outside of the limits set by the reference, then the regulation unit must provide an adjustment to the unit generating the output so as to diminish or increase the output levels. In the case of the GCU, the output voltage from a generator is sensed by the GCU and compared to a reference voltage. 
  • Overvoltage Protection 
an Like the voltage regulation feature of the GCU, the overvoltage protection system compares the sampled voltage to the reference voltage. The output of the over-voltage protection circuit is used to open the relay that controls the output for the field excitation. These types of faults can occur for a number of reasons. The most common, however, is the failure of the voltage regulation circuit in the GCU. 
  • Parallel Generator Operations 
 paralleling feature of the GCU allows for two or more GCU/generator systems to work in a shared effort to provide current to the aircraft electrical system. Comparing voltages between the equalizer bus and the interpole/compensator voltage, and amplifying the differences accomplishes the control of this system. The difference is then sent to the voltage regulation circuit, where adjustments are then made in the regulation output. These adjustments continue until all of the busses are equalized in their load sharing. 

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