28Vdc, 10-50A, 5A Field current, “Type B” Single Engine Generator Controllers.

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Product Description

28Vdc, 10-50A, 5A Field current, “Type B” Single Engine Generator Controllers.

What’s included:

  • Installation Drawing & Troubleshooting Notes
  • Warranty Card
  • Product Eligibility Catalog (PEC)

Product Features:

Voltage Regulation, IC Sense Referenced

This “type B” Voltage Regulator (VR) controls the Generator’s output to keep the aircraft electrical system voltage at the specified 28V by switching power to its field. If the Generator output voltage is less than the VR set point, the switch is closed, current flows to the field and the Generator’s output increases. When the Generator’s output voltage exceeds the VR set point, the switch opens, the field current flow stops, and the Generator’s output decreases. The switching of the field occurs hundreds of times a second in order to keep the output steady.

Reverse Current Protection

The Reverse Current (RC) Protection circuit blocks the battery current from going back to the generator. It allows current to flow only from the generator to the battery and the system.

Current Limiter

The Current Limiter (CL) controls the maximum output current the generator can produce. It turns off the field excitation when the output current exceed the CL set point. It allows normal field excitation when the generator output is below the GCU CL set point. Loading the system beyond the CL point will cause the bus voltage to drop.

Over Voltage (OV) Protected

The GCU’s design will cause the field current path (between the field and power input, i.e. terminal C) to open if the system experiences OV condition. The GCU does not protect the system against externally induced OV faults like those caused by a pilot pulling-out and pushing-in the main generator output circuit breaker while the engine is operating at high speed. If the generator’s main output breaker is pulled, the generator (field) switch should be turned off before the main breaker is pushed back in.

Trouble-Shooting Lights on Unit

The on-unit system Trouble-Shooting Lights, TSL, identify how the system is operating and, helps with system testing and troubleshooting. The lights indicate Generator Off/On-line (GO, Green), Voltage Regulation and Field-to-Ground short (VR, Green/Off/Red), Current Limit (CL, Red), and Over-Voltage (OV, Red).

Other Features:

  • Increase Regulator Life
  • Eliminates the voltage drift of Carbon Pile Regulators
  • Footprint Compatible to Delco-Remy’s VR
  • Not Temperature Sensitive
  • Prevents Regulator cycling at low RPM
  • Eliminate Regulator Noise
  • More Precise Current Limit
  • Prevents Battery Current Flowing to the Generator
  • GCU will not cause OV fault in the system
  • Reduce Trouble-Shooting Time
  • Products available for 5A, 8A and 12A field current generators.
  • Products are available for generators rated for 10 to 50Adc.

Additional Information

Weight2 lbs
Dimensions5.80 × 3.00 × 2.59 in
Model Number


Voltage Reg. (VR)

28.2V ± 0.4V

Max Field Current



Type B


Product SupportPDF Requires Acrobat Reader

Warranty Policy

Click the links below to download warranty policy in .pdf format.

Warranty Policy (New Manufactured) PDF Requires Acrobat Reader

Warranty Policy (Recertified) PDF Requires Acrobat Reader

G2501P - Zeftronics


Click the links below to download the .pdf


Product Connector FAQ PDF Requires Acrobat Reader

General Product

GCU Cross Reference (Coming Soon)

ACU Cross Reference (Coming Soon)

OVR, OVS, Cross Reference (Coming Soon)

How To

How To Read the Cross Reference Chart FAQ (ACU) PDF Requires Acrobat Reader

How To Read the Cross Reference Chart FAQ (GCU) PDF Requires Acrobat Reader