Load-sensing System Research Articles

Governors with Load Sensing

Load-sensing governors have become a commercial reality since the 1939-45 war, but their use appears to have been restricted largely to applications where the load is an electrical machine. The need to reduce transient speed errors in order to maintain constant frequency during large load changes in electricity generation and computer applications is well recognized. This paper reports on improvements made in the performance of speed governors, by the addition of load sensing, when applied to normally aspirated reciprocating internal combustion engines. Its aim is to stimulate interest amongst engineers seeking improvement in the transient performance of various kinds of governed machinery. A simple linearized theoretical treatment of the load-sensing control system, which predicts, approximately, the behaviour of a real system, is presented in this paper. Experimental tests, carried out on automotive 4-stroke petrol and diesel engines, indicated that load changes could not occur with absolutely zero temporary droop, and that the test arrangement was more stable at high loads. Comparison of transient performance with and without load sensing showed that the 10 per cent temporary droops, required by B.S. 649 and B.S. 3109, was never achieved without load sensing. With load sensing, an improvement by a factor of 4 was recorded, reducing the temporary droop below the requirements of the specifications.