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