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Coex Training

Voltage Transformers

Voltage transformers carry full system voltage but no significant current.  They have a fine wire of many turns on the primary winding (very high resistance and inductance) connected between the phase conductor and earth, and…

Earthing Switches

Earthing switches are usually installed in combination with an isolator and the two should be interlocked electrically or mechanically to ensure that the isolator is open before the earthing switch is closed, and conversely that…

Isolators

Isolators are simple devices with contacts invariably comprising a moving blade going into two parallel fixed contact faces. The fixed contact faces are usually made up of a number of spring-loaded fingers. The best isolators…

HV training

Circuit breakers

The following basic types are available, typically rated at 350 or 500 MVA at 11 or 22 kV respectively: bulk oil minimum oil air break vacuum SF6 Circuit breakers are designed to deliberately create an…

Power System Switches

The main four different switches used in a power system are: Circuit breakers are designed for controlled closing and controlled or automatic opening of load and fault current. Their duties are to close onto a…

Arc Flash/Arc Blast PPE

The incident energy determined at each assessable location will fall within a defined arc flash/arc blast PPE category, as defined in the table below. Incident Energy PPE Category Cal/cm2 >1.2 to 4 1 >4 to…

Arc Flash/Arc Blast Hazard Labels

Arc flash/arc blast hazard labels inform personnel of the arc flash/arc blast hazard and the required PPE at each switchboard or arc flash/arc blast hazard location. The labels should present the following information: electrical hazard…

HV in Port Hedland

Arc Flash/Arc Blast Risk Assessment

The likelihood of an arc flash/arc blast event is dependent upon the type of activity being undertaken at the time. It is generally accepted that the greatest likelihood occurs when there is direct interaction by…

Consequences of Arc Flash/Arc Blast

Arc faults are potentially fatal to any personnel in the vicinity. The intense heat of the arc flash/arc blast can severely burn human skin and ignite the clothing of anyone within several feet of the…

SAD - no go zone diagram

Understanding Safe Approach Distance/SAD

The safe approach distance (SAD) is based on an “exclusion zone” principle. This principle defines an area around an exposed conductor into which no part of the person, mobile plant or object (other than approved…