Technical notes of interest to Marine Engineers
Consideration for Electronic Governors
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Important considerations to review during installation and calibration of electronic governors on industrial engines.
Electronic governors are designed to improve the output capability of diesel and gas engines. They accomplish so by automatically controlling the fuel supply to the engine in accordance with load requirements. When properly calibrated for a particular application, your electronic governor should provide unlimited hours of operation. Installation of a governor system consists of two parts: physical installation and electrical wiring of its components. The following provides a general description of issues that should be considered when installing such a system.
As most electronic devices, governors are sensitive to electrical noise generated by radio equipment, magnetic fields, pulsating currents and heavy relays. Precautions must be taken when wiring the system, to protect against electrical noise. A recommended practice includes the use of shielded or twisted pair wiring on power and speed sensing circuits. Shielded wire has the effect of blocking electrical noise away, while twisted pair wiring creates a canceling effect between the two wires in the circuit. Possible symptoms of electrical noise are constant or intermittent engine speed instability, and erratic response to calibration efforts. At times, symptoms may occur due to noise created by equipment momentarily passing by the electronic governor and hence may be difficult to troubleshoot. When such behavior is observed, it is always good practice to review the systems wiring.
Physical installation of the governor is just as crucial. Mechanical linkage between the actuator and the fuel system must move freely but not loosely. Any play between connecting parts will result in erratic operation of the governor. Surrounding conditions must be kept free of excessive moisture and debris as they could accumulate and affect linkage movement.
Calibration of the governor controller is performed after the installation. Proper calibration is important to obtain the best performance out of the governor system. Basic controllers provide adjustments for engine speed and gain. Once the engine speed is set to the normal operating level, it should never have to be adjusted again. Gain adjustments provide for fine tuning of the magnitude of speed corrections and the response time between error and target speed conditions. After proper calibration, the governor is responsible for maintaining the target engine speed regardless of load changes (provided the engine is properly sized for the load).