3-Phase Testing

The Standard AS/NZS 3760:2010 covers testing of both 240 volt (Single Phase) and 415 volt (3-Phase) electrical equipment, and requires that a range of tests be carried out on the equipment.  Tests performed on 415 volt electrical equipment will require the use of test equipment appropriate to the task.

The Tests

AS/NZS 3760:2010 identifies three tests that are required to successfully test 3-Phase appliances.  They are: –

  1. Earth Continuity;
  2. Insulation resistance; and
  3. Earth Leakage

Earth Continuity and Insulation Resistance

These two tests are essential to be able to claim compliance to AS/NZS 3760:2010.

The Insulation Resistance test measures the resistance provided by the equipment’s insulation.  As you would expect, this needs to be very high.  This resistance is measured in Ohms (Ω), and the minimum required for this test is 1MΩ (Megohm) which is 1,000,000 ohms

The Earth Continuity test measures the resistance provided by the equipment’s earth wire.  In order for current to pass to earth from the equipment as quickly as possible this resistance needs to be very low.  Consequently, the maximum resistance allowable for this test is less than 1 Ω.

Earth Leakage

This test is used to verify that the leakage between the mains conductors of the equipment to the earth pin is at a satisfactory low level to avoid electrocution.

The Earth Leakage test is measures the extent of current flow and for this reason the equipment needs to be energised.  This current flow is measured in Amperes (amps), and needs to be very low for this test.

When performing this test the leakage current values obtained shall not exceed 5mA (milliamps), or 0.005 amps.

3-Phase RCDs

Another test that can be carried out on 3-Phase equipment is RCD triptime tests.  Tests on three or four pole RCDs used on a three-phase supply are conducted with a three-phase supply connected.

There are three tests that can be carried out on 3-Phase RCDs.

  • Trip Test – Test for correct operation (both current level and time)
  • No Trip Test – Tests against nuisance tripping
  • Fast Trip Test – Tests for current/time to lessen electric shock hazard.

The testing AS/NZS 3760:2010 requires for 3-Phase RCDs is firstly a check of the manual trip function on the RCD, then a Trip Time test which measures both current level and trip time.

To satisfy the standard only the Trip Test is required.  The maximum triptime for 3-Phase RCDs must not exceed 300 milliseconds (ms).