The PAL GE/MAC replaces outmoded and obsolete electronic components. The gas turbine temperature control was made for turbines manufactured in the 1960s. The replaced components include the following:
Temperature Averaging Cabinet (eliminated)
GE/MAC (eliminated)
MV/I Current Amplifier
Programmer
Millivolt Flame Detector, 28TC (eliminated)
Electro-pneumatic Transducer, 65EP (replaced with modern unit)
Fig. 2: 65EP Electro-pneumatic
Transducer
The PAL GE/MAC utilizes a programmable logic controller (PLC) manufactured by Horner Electric and software by Cscape. The system accepts twelve thermocouples and conditions each millivolt signal. Once any faulty thermocouples are rejected (shorted, grounded or open circuit), the remaining millivolt signals are averaged and converted to a 4 to 20 milliamp output.
Fig. 3: Original Fuel Regulator
installed on Accessory Gear
Finally, this signal is sent to a new 65EP electro-pneumatic transducer (rated 4-20 milliamperes). Air signal goes to the existing fuel regulator (3 to 27 psig).
The Fuel Regulator remains unchanged and functions as originally installed to control fuel flow to the gas turbine.
