Press Release October, 2021

OSM38 Recloser Achieves One Second Internal Arc Classification

NOJA Power OSM Recloser Arc Fault Testing

Australian electrical engineering firm NOJA Power is celebrating the successful type testing of their 38 kV OSM Recloser product for 1 second arc fault classification at 12.5 kA.

Internal Arc Classification (IAC) is an assurance of the equipment’s ability to safely vent arc energy in the unlikely event of an internal arc fault. This arduous test sees a deliberate internal short circuit initiated in the device, delivering 12.5 kA of fault energy for 1 second, as dictated in the IEC 62271-200 medium voltage switchgear IAC standard.



NOJA Power switchgear views IAC compliance as essential for all their equipment, as the devices are most commonly applied in service in public spaces and the safety of the general public in the product vicinity is essential.

“NOJA Power has always considered IAC an important safety feature of our products,” says NOJA Power Group Managing Director Neil O’Sullivan.

“The extension of the 200 millisecond rating to a 1 second rating for the OSM 38 product was in response to market demand, and this test result is very pleasing to see the safety margin and redundancy built into our original design.”


The NOJA Power OSM Recloser device post-test, with successful operation of the Arc Fault Vent relieving pressure and preventing explosion. © NOJA Power 2021

The NOJA Power OSM Recloser device post-test, with successful operation of the Arc Fault Vent relieving pressure and preventing explosion. © NOJA Power 2021

The OSM38 Recloser was previously certified for 200 millisecond arc fault rating, however this extension to 1 second was achieved with no modifications to the design. The tests were conducted at Plus ES in Lane Cove Sydney, with copies of the test reports available shortly from NOJA Power.