101 Basic Series - Module 05 - Post Assessment
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A circuit breaker that uses SF
gas and is frequently used by European manufacturers employs the __________ method for arc extinguishing.
As a circuit breaker opens or closes, the moveable contact maintains its position, while the fixed contact makes or breaks the circuit.
Thermal magnetic trip units act to protect the circuit breaker itself.
The two types of trip units are _______________ and ____________.
Current transformer, electromechanical
Flux-transfer shunt, current transformer
Electronic, flux-transfer shunt
Peak value sensing in an analog trip unit never causes false tripping and offers more accuracy than digital trip units.
Circuit breaker frames are usually constructed of bolted and welded metal or molded insulating material.
Circuit breakers are commonly used in loadcenters, panelboards, and switchboards.
The surge of amperage created during an electrical failing is called the __________.
The two steps in the two-step stored energy mechanism are charging the closing spring (storing the energy) and releasing energy to close the breaker.
In a thermal overload, temperature build-up occurs between the insulation and the conductor.
A method for extinguishing arcs that moves the arc through an arc divider, splitting and cooling it is known as ____________.
Electromagnetic trip units are both temperature and harmonic insensitive.
A circuit breaker that is bolted in and hard wired to the frame is known to be _____________. Power must be turned off to remove and replace the breaker.
The key to a circuit breaker's short circuit interrupting capability is its ability to extinguish an arc quickly.
he current transformer of an electronic trip unit is used in each phase to monitor and __________ the current to the proper input level.
Keep the same
Circuit breakers are only used in loadcenters, panelboards, and switchboards. They are never to mounted in separate enclosures.
Molded insulated frames are made from materials such as glass-polyester or thermoset composite resins.
Digital trip units look at selected discrete points on a curve and make a summation of those points. This helps reduce false tripping.
A trip unit is the circuit breaker's "intelligence", which trips the operating mechanism open in the event of an overcurrent condition.
Electromechanical trip units have increased accuracy, repeatability, and discrimination over electronic trip units.
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