Volume 16, Issue 4 (July 1988)
Simple Measuring System for Electrical Energy Consumed by Auxiliaries for Advanced Batteries
We have constructed a new measuring system of electrical energy for widely varying load current between 0.5 and 100 A using a controller for the current transformers (CT), a personal computer, and wattmeters. This system possesses special characteristics as a controller circuit of the CT. When the load current changes greatly, the most appropriate first terminal of the CT is instantaneously selected by the controller to provide an accurate measurement.
Firstly, the response of the system to varying power factors is discussed. Electrical energy was measured to an accuracy of ±0.45% for constant current loads with power factors between 1.0 and 0.4 and to an accuracy of ±0.68% for on-off current loads at every 5 min with power factors of 1.0 and 0.9. Secondly, the effect of distorted waveforms is discussed with regard to the accuracy of the system. It was verified that the system was scarcely affected by firing angles of the load current between 45 and 135°. In conclusion, the measuring system is applicable to the auxiliaries of the 10 kW class advanced batteries and also to other general loads possessing various power factors and distorted waveforms.