Voltage Dip 09/03/2022 6:10PM

A voltage dip was reported in the Jurong-Pioneer area at around 6:10PM, due to a 22kV cable fault.

Our office, a 15-20mins drive away (Jurong East – Boon Lay Way) recorded a drop in voltages of about 13% (from 420V to 366.5V) or about 8% (if referred to nominal voltage of 400V), as seen below.

Measured at 400V (Line to Line)

One may wonder how could a fault in Pioneer area affects the voltages in Jurong East?

Our local distribution grid is densely interconnected, resulting in a high-reliability electricity network. Total blackouts are rare. But interconnectivity brings about a small disadvantage. Any fault will be seen/felt (in the form of a voltage dip) by everyone who is connected. The seriousness of this dip will be dependent on the types of faults and the electrical distance between you and the fault point.

Based on past experiences, for a voltage disturbance of about -10% to be seen at another 22kV network, it will need to be a significant fault causing a voltage dip in the range of 70-80% in the fault area.

Our office is in another 22kV network, which is connected to the fault area via the 66kV network path, as illustrated below.

Such drop in voltages usually do not cause much problem(s) to the equipment-end (especially typical office loads), as observed in the following Irms trends during this voltage disturbance.

Vrms / Irms Trends During the Event