Business Products
Products Grid

Upgrading and Renovation Project of a Low-resistance Grounding System


In a city of Zhejiang, a system upgrading project from 10 kV to 20 kV has been completely implemented since 2011. Instead, the low-resistance grounding systems are applied. However, the earth fault tripping occurred frequently due to serious accidents arising from birds. The customers in the chemical fiber industry required a lot for the power supply quality, but short-time power failure had great impact on their product quality. Frequent tripping affected the normal industrial production of many enterprises. So the power supply authority often received lots of complaints.


The original two low-resistance systems are upgraded into intelligent resistance grounding units, so that quick reactors can fulfill accurate compensation and eliminate earth faults in case of transient grounding.

Operation Effect:

Comparison of Six 20 kV Lines for Busbar Section #1 in this Substation before and after Renovation (between June 2011 and March 2012)


Before renovation (low-resistance grounding)

After renovation (intelligent multi-mode grounding)


June 2011

July 2011

August 2011

September 2011

From October 2011 to March 2012

Number of earth fault tripping







During low-resistance grounding, there were 32 earth fault trippings in four months. Since the operation of intelligent multi-mode grounding systems, such tripping occurred twice only in half a year. Apparently, such solution solved the frequent tripping problem and significantly improved the power supply reliability.


  • Summary
  • case
  • download
Copyright ©2005 - 2017 Guangzhou Zhiguang Electric Ltd.