Effect of voltage sags on sensitive loads in the 240 V/50 Hz Malaysian distribution systems

Voltage sags have emerged as one of the most serious power quality problems, particularly for sensitive loads. This paper presents the results of a study on the effects of voltage sags on selected equipmentsin the context of the local Malaysian power distribution system. Extensive tests were performed on three categories of equipment sensitive to voltage sags namely, personal computers (PCs), fluorescent lamps (FLs) and ac contactors. For a predefined malfunction criterion, sag depth and duration were varied to construct individual voltage immunity curves for each test sample. The effect of point on wave of sag initiation on contactors was also studied. The predefined malfunction criterion for PCs, FLs and ac contactors are standard reboot, zero luminance and contact disengagement condition, respectively. For each category of equipment, a generic voltage tolerance curve was developed in order to compare with the common industry standards such as the SEMI F47. Test results show that the PCs used in the local distribution have relatively high tolerance level while lamps and contactors show similar voltage immunity levels that were reported in earlier studies.