We realised in order to  further improve core quality, and support our investigations into the UNICORE, we needed a method of accurately and repeatably measuring core performance. We teamed up with Professor Andrew Baghurst of Caltest Pty Ltd  to resolve the magnetising and power loss curves into their respective vector components.

Caltest Pty Ltd, is an independent NATA certified testing laboratory near Adelaide headed up by Professor Andrew Baghurst. The team at Caltest have been instrumental in the qualification of many core (and transformer) tests during this time. Together we have managed to resolve many issues and clarify CT and transformer design using factual evidence. There has been more than one 'myth busted' along the way.

As a result of our combined research we have developed a progression of 'test benches' for our own use

The MKI

Our first attempt to automatically test cores over the entire range of flux densities for either a GOSS or Mumetal core. Two years after commissioning it had tested over 80,000 cores with a cycle time of 1 minute per core. Although slow (compared to future models) it did teach us several important points:

• line voltage fluctuations can seriously affect the test
• leakage reactance is a major issue for cores with a large MPL compared to their section size
•  accuracy of one part in 100,000 just wasn't good enough for low flux density readings.

The MKII

The lessons from MK I's development led to considerable improvements, The MK II features a test cycle time of only 6 seconds (1/10th of its predecessor) this unit is a mumetal only device capable of taking simultaneous voltage and current readings at 40,000 flux density set points over the entire flux range of a core. Label printing, real time hysteresis loops plus graphical and tabulated results on the front panel have eased the operator work load and decision making. The device is totally independent of line voltage fluctuations, self calibrates for leakage reactance and can read the magnetising current down to 1/10th of the MKI version. With an accuracy of 1 part in a million we can accurately read the magnetising current down to 0.007T.

The MKIII

Currently under development the MK III benefits from it's predessors and over 200, 000 core tests. With all of the same features of the MKII, it has 10 times the power enabling us to energise cores weighing 1/4 ton but still retain the 1 part in a million accuracy. This test bench can produce both magnetising curves and power loss curves for any GOSS core. Core mass is automatically measured, labels printed, multi frequency testing selectable and test data archival.

Manual Test Rig

• Now Available!

The MTR is an industrialised version of our laboratory based test equipment. Unlike the MK series of test benches this is a three phase unit with quick connect cabling to enable fast and accurate testing of 3 phase cores. Any type of 3 phase core: Evans, 4 loop or flat stack can be tested for magnetising current and power loss using the manual variac. The MTR can test single phase cores simply by changing to the single phase test leads..