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The GR-1’s ECU has three main features that prevent undesirable function of the GR-1. The first function is the low oil pressure shutdown switch. This switch is set to trip at 25 PSI or below. The oil pressure switch has two functions: one - to shutdown turbine in the event of losing oil pressure to prevent bearing damage and two - to shutdown the turbine in case of overheating. When the turbine overheats, the oil loses it’s viscosity and the oil pressure will drop because the pump cannot pump it fast enough through the hydrostatic bearings thus tripping the switch.
The second feature of the GR-1’s ECU is the combustor pressure switch. This switch is designed to trip at 0.5 PSI or below. The combustor pressure switch has two functions also: one - to shut off the ignition coil when operating pressure is achieved thus saving power and two - to shutdown the fuel solenoid in the event of losing compression due to flameout or the turbine stopping. This switch prevents the fuel from burning outside of the combustor in the event of a combustor breech or rotor crash (turbo malfunctioning).
The third feature of the ECU is the emergency shutdown switch. In the event of a system malfunction, the operator can push this button and the turbine’s fuel will be shut down, stopping the combustion. This circuit is utilized by the two pressure switches in order to shut the turbine down as well. The GR-1 control panel is fairly simple, with only a couple panel lamps and switches but it is effective.
To start the GR-1, you would turn on the main switch which controls the lubrication system. Once oil pressure is achieved, the control panel will allow the fuel circuit to be turned on. Before the fuel can be turned on, the turbine must be spooled up. Once the turbine is spinning at least 5000 RPM, the fuel can be turned on AT LOW THROTTLE. After the fuel is flowing, the ignition circuit can be turned on, lighting the combustor. Once operating pressure is achieved, the ECU will turn off the ignition. If the turbine is at too low of an RPM to sustain its operation, the combustor pressure switch will shut down the propane to prevent an over heat.
The combustor pressure switch will also shut down the fuel if the diffuser hose blows off. This situation could cause a large fire ball to engulf the engine and operator so I had to incorporate the switch for safety. To shut down the GR-1, you can turn off the fuel switch or do what I prefer to do, lowering the throttle below the operating pressure and testing the low combustor pressure switch. A basic diagram of the GR-1’s ECU is posted below. This diagram gives you a basic idea of the ECU in “ladder” form.
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