NOJA Power

Technical Article

Updated 03/2023

Solving Mining Medium Voltage Power Applications with the NOJA Power GMK


The NOJA Power GMK Ground Mount Kiosk Circuit Breaker is an integrated switchgear assembly perfectly suited for Mining Power protection and control. Mining power supplies often operate in challenging environments with high levels of pollution. NOJA Power’s GMK is designed to thrive in these operating environments, enclosing all switchgear, controlgear and communications apparatus in an IP65 rated enclosure. This environmental resilience combined with cost savings of an “off the shelf” standard switchgear assembly has prompted mining installations for the GMK all over the world.

NOJA Power GMK’s used to connect Generators to an Australian mine
NOJA Power GMK’s used to connect Generators to an Australian mine

NOJA Power’s GMK product uses an OSM Recloser as the core switchgear, controlled by either the NOJA Power RC-10, RC-15 or RC-20 Recloser Controller. Key to mining applications, the NOJA Power GMK can offer Sensitive Earth Fault protection to 200 mA, allowing the assembly to protect medium voltage connected industrial equipment.

Sample single line diagrams have been made available here:

Single Line Diagrams

The optional inclusion of an interlocked earth switch allows operators to apply conventional mining safety lockout practices, simplifying maintenance.

For some mining applications, mobility of switchgear becomes a useful asset. With the GMK being a standalone switchgear assembly, the product can be relocated on site as power requirements change. This versatility reduces ongoing engineering work, providing further operational savings for mining operators.

NOJA Power GMK for Underground Cable Protection in Western Australia
NOJA Power GMK for Underground Cable Protection in Western Australia

Lastly, NOJA Power’s GMK includes extensive power quality monitoring capabilities. Specialist Medium voltage power quality monitoring equipment can present a sizeable site investment, but failure to detect power quality issues can cause major equipment damage. The NOJA Power GMKs integrated power quality monitoring warns engineers early, providing an opportunity to mitigate costly equipment failures.

“Our GMK product finds application in a lot of medium voltage distributed generation mining applications and with the recent release of the arc fault contained and vented version of the product has now been approved or used by many of our electricity utility customers in general public access applications,” says NOJA Power Group Managing Director Neil O’Sullivan.
NOJA Power GMK (Right) commissioned in an Overhead to Underground Assembly
Left to Right, Dean van Wijk (General Manager POWINS), Neil O’Sullivan (Group Managing Director NOJA Power), Julian Rauwendaal (Operations Manager QLD POWINS)

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