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Time-current curves are used to show the amount of time required for a circuit breaker to trip at a given overcurrent level.
Time-current curves are typically shown on a log-log plot. Figures along the horizontal axis of the curve represent the continuous current rating (In) for the circuit breaker, figures along the vertical axis represent time in seconds.
Drawout circuit breaker connected inside switchgear cell. Photo: EATON.
There are many things can happen to a circuit breaker on its journey from the factory to facility, and while they are always tested by a manufacturer prior to shipping, the following checks and tests should be performed at a minimum to ensure that a new low voltage circuit breaker is ready to be placed into service.
Electric shock occurs when your body becomes part of a closed circuit and electric current flows into one part of your body and out another, like into your hands and out of your feet for instance.
Direct current (DC) is generally less dangerous than alternating current (AC).
Transformer fluids require sampling from different locations based on their specific gravity (SG).
One major element of a transformer maintenance program is periodic testing of its insulating fluid - and obtaining a good fluid sample starts with knowing where to draw the sample from.
Transformer fluids require sampling from different locations based on their specific gravity (SG).
Insulation testers come in a variety of sizes and output voltages depending on its specific application.
Most commonly referred to as simply a "megger," the insulation resistance test set (or Megohmeter) is used to determine the condition of insulation on various types of electrical equipment like cables, transformers and switchgear.
Depending on the model, Square D Micrologic trip units may feature self-protection/advanced-protection (AP) functions in addition to the typical over current functions found on most low voltage power circuit breakers.
Hard hats must be worn when working in areas where there is a potential for injury to the head from falling objects.
Wearing a hard hat is one of the easiest ways to protect the most important part of your body - the head. A head injury can kill you or even impair you for life. Hard hats can protect you from impact and penetration hazards as well as from electrical shock and burn hazards.
Ground Resistance Test Set with leads and accssories. Photo: AEMC
In electrical power distribution systems, a protective ground conductor is an essential part of the safety earthing system. For measurement purposes, the Earth serves as a somewhat constant potential reference against which other potentials can be measured.
Knowing how to properly test an electrical ground system is essential to ensure that it has an appropriate current-carrying capability to serve as an adequate zero-voltage reference level.
