Many of us have the need to also test and tag 3-phase appliances. But the testing of 3 phase appliances is not as straight forward at it first might seem.
One of the biggest considerations when testing 3 phase appliances is, how can it be done effectively?
For many single phase earthed appliances, an earth continuity and insulation test is sufficient to test the electrical integrity of the appliance. However, the Australian standard specifies that for appliances that must be energised to be in the 'on' position a current leakage test shall be performed. For that reason, many single phase appliances also require a current leakage test. 3-Phase appliances are no different in this respect.
3-Phase appliance 'on' switches
On most 3-phase appliances, contactor relays are used to switch the appliances. Typically, these can only be operated when the appliance is powered. Therefore, 3-phase appliances are more commonly, appliances that must be energised to be in the 'on' position and consquently, many experts would consider that a current leakage test should be performed.
However, testing 3-phase appliances for current leakage is neither straight forward, nor something that can be performed without costly test equipment.
Help -> For more information as to why current leakage testing is required, see Best Practices Guide to Testing and Tagging Basic 3-Phase adaptors for appliances testers
Some 3-phase adaptors are available for single phase appliance testers which allow 3-phase appliances to be tested. They normally consist of a single phase plug attached to a 3-phase extension lead socket.
These allow for the earth continuity an insulation of a 3-phase appliance to be tested. However, as previously mentioned, many 3-phase appliances have relays on the power circuits. These adaptors cannot test beyond these circuits so have many limitations. By using such adaptors, some appliances will not be tested in accordance with AS/NZS3760:2003. These adaptors typically cost about $150.00 - $350.00 + GST. Circuit diagrams are available for those that would like to manufacture their own.
Current leakage 3-Phase adaptors for appliances testers
As many 3-phase appliances require a leakage test, 3-phase adaptors exist which allow 3-phase appliances to be tested using a current leakage test. The adaptor is basically used like an extension lead. The single phase appliance tester is used to make an earth continuity reading while a measurement of current leakage is measured using the device while the appliance runs. These adaptors can test appliances to check compliance with AS/NZS3760:2010. However, they tend to be costly devices and you can expect to pay in excess of $700.00 for such a device. See the TTS3PHAD7 on our website.
Other 3-Phase current leakage tests
A 3-phase leakage adaptor is not the only method by which 3-phase appliances can be tested for current leakage. Other methods would include measuring the current present in the earth core while the appliance is running or by using a current leakage current clamp. While both these options are significantly lower in cost, they may not be appropriate for a non-qualified electrician. Details on testing using these methods can be found in Best Practices Guide to Testing and Tagging.
Insulation and Continuity meters
For those who decide that the Insulation and Continuity testing of their 3-phase appliances is sufficient, an insulation and continuity meter may well be the most versatile and low cost solution available. Not only will this allow the insulation of each conductor to be tested independantly, but it also provides a simple means of testing the polarity of 3-phase extension leads too. The cost of an insulation and continuity meter maybe even less purchasing a single adaptor lead for a PAT.
Some appliance testers such as the Metrel 3309, Metrel 3310 and Seaward Primetest Elite feature 'point-to-point' type testing whereby the instrument can safely be used with probes in a similar way to an continuity and insulation tester.
Other issues relating to 3-phase equipment
While current leakage testing may be the most thorough method of testing 3-phase equipment, there are still many other issues relating to testing 3-phase equipment effectively. One consideration must be whether it is safe for a run test to be carried out on the equipment.
Some 3-phase appliances are not only large but can be dangerous if operated by non authorised personell. It is quite likely that the authorised personnell may not be available at a time when the equipment is required to be tested.
Deciding how to approach 3-Phase Current leakage testing
Questions you'll need to be able to answer before deciding on the most appropriate route forward include:
In some instances it may be more effective to have the 3-phase equipment hard wired, rather than tested on regular intervals.
3-Phase Portable Appliance Testers
Because there are so many variations in the way 3-phase appliances can be tested. And, so many variations in types of 3-phase plugs and sockets, very few test and measurement equipment manufacturers have dared to produce a purpose built 3-phase appliance tester.
Instead, test and measurement equipment providers have sought to provide reasonable alternatives - like current leakage adaptors such as the TTS3PHAD7, insulation and continuity adaptors for single phase PAT testers, and wiring diagrams. Many providers also recommend that 3-phase appliance testing is only carried out by licensed electricians.
