\n– Similar “incomplete” earth loop values were obtained at the LV Main Switchboard. “OL” when measured between Phase L1 and Earth. Had used different sets of earth loop testers.
\n– Thorough checks were conducted on the distribution transformer, earth cables and the neutral-ground connection at the transformer.
\n–\u00a0 Loads on this particular switchboard include the building’s chiller systems and some tenants’ loads.
\n– Was reported normal earth loop values could be obtained when the chiller system is not in operation.<\/p>\n
Recall:<\/em> Earth Loop Impedance Test<\/em><\/strong> Recall: Earth Loop Tester<\/strong><\/em> Findings<\/strong><\/em> – Apart from one failed attempt via the multifunction tester, subsequent tests produced repeatable earth loop impedance values across all the 3 phases.
\n– One of the tests conducted for an Electrical Installation “Pass” Certificate.
\n– To ensure when a fault occurs in an electrical installation, sufficient current will flow to operate the fuse or circuit breaker protecting the faulty circuit within a pre-determined time.<\/p>\n
\n– Operates by inducing a current from the Supply system<\/strong>, by introducing a calibrated load between the phase conductor and the protective earth.
\n– And then monitors the voltage difference.
\n– Comes in various forms (Multifunction tester vs. Dedicated tester); (3-wire types L+N+E vs 2-wire types L+E)<\/p>\n![\"\"](\"http:\/\/powerquality.sg\/wordpress\/wp-content\/uploads\/2018\/10\/tns-earthloop.jpg\")
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\n– Conducted separate earth loop tests at LV Main Switchboard and monitored the quality of supply.<\/p>\n<\/a>
\n– “OL” when measured between Phase L1 and Earth, used “K-brand” earth loop tester(s).
\n– VTHD on “high side” but expected due to the a few nos of variable speed drives being used at the Chiller system.
\n– Phase L1 – noticed multiple zero crossings.<\/p>\n