CHAPTER 2, OVERCURRENT PROTECTION

Question 1

safeguards the circuit components from overheating when the current flowing through the circuit reaches an _______ that will cause an excessive or dangerous ________ rise in conductors

Answer 1

OVERCURRENT PROTECTION (OCP) DEVICE, amperage, temperature

Question 2

_________ and __________ serve as automatic overcurrent protection devices that are designed to open a circuit if the amount of current, in amps, that flows through the circuit exceeds the OCP device rating

Answer 2

fuses, circuit breakers

Question 3

an OCP that acts as a switch that can be opened and closed manually, and it automatically “TRIPS OFF,” which opens the circuit when the current flowing through it exceeds the circuit rating.

Answer 3

CIRCUIT BREAKER

Question 4

A ___________ classifies it in volts (V) and current carrying capacity in amperage (A). This is the maximum voltage the circuit breaker can carry.

Answer 4

voltage rating

Question 5

When current flow is excessive, the circuit breaker heats up, bends, and trips a release that opens contacts and interrupts the current flow.

Answer 5

THERMAL-MAGNETIC TYPE

Question 6

• When tested in the open air, it can carry a load of about __% above its rating and hold __% above its rating for a minute.

• Other characteristics include the current-limiting feature that instantly trips at its rating and the ___% rated part limiting the load to __% when the load is continuous for over 3 hours.

Answer 6

THERMAL - MAGNETIC TYPE 10, 50,100, 80

Question 7

THE UL (UNDERWRI TERS LABORATORIES, INC.) STANDARD CIRCUI T BREAKER RATINGS FOR ELECTRICAL CURRENT:

FOR DC

Answer 7

125 V, 250 V, and 600 V

Question 8

protecting a single Ungrounded conductor.

Answer 8

single pole (CIRCUIT BREAKERS THAT PROTECT THE UNGROUNDED (HOT) CONDUCTORS IN A CIRCUIT)

Question 9

when protecting two ungrounded conductors such as on a 240 V circuit.

Answer 9

two pole (CIRCUIT BREAKERS THAT PROTECT THE UNGROUNDED (HOT) CONDUCTORS IN A CIRCUIT)

Question 10

used when protecting three ungrounded conductors on a three-phase circuit.

Answer 10

three pole (CIRCUIT BREAKERS THAT PROTECT THE UNGROUNDED (HOT) CONDUCTORS IN A CIRCUIT)

Question 11

An overcurrent protective device with a circuit-opening fusible part that is heated and severed by the passage of overcurrent through it (Smith, 2007).

Answer 11

fuseS

Question 12

• act as “electricity’s safety valve” by providing a weak link in the circuit path that, when properly applied, will melt and open the circuit to minimize or eliminate any damage that can be caused by an excessive flow of current (Sharma, 2018).

Answer 12

fuseS

Question 13

It comes in a screw-type configuration with a sight glass that shows if the fuse is blown or not (Hanvey, 2015).

Answer 13

plug fuseS

Question 14

The older type fuses have a brass screw thread on the side and a central contact point.

Answer 14

plug fuseS

Question 15

cylindrical in shape and have the contact points at either end. These fuses are used in fuse panels and disconnect for amperages over 30 amps (Sharma, 2018).

Answer 15

cartridge fuse

Question 16

• A special kind of fuse that allows electrical surge for a short time before it blows. Its unique design can bear electricity overload in a repeated cycle for a short period without blowing (Andrew, 2010).

• They are desirable on circuits serving electric motors such as air conditioners and machinery because motors draw much more current at a startup than during regular operation.

Answer 16

time delay fuse

Question 17

• An OCP device’s ______________ is the highest amperage it can carry continuously without exceeding a specific temperature limit.

Answer 17

overcurrent rating

Question 18

• The overcurrent rating of an OCP is listed in amperes, such as ___ A, __ A, or ___ A.

Answer 18

15, 20, 30

Question 19

The highest current at rated voltage that a device is intended to interrupt under standard test conditions (Edvard, 2015).

Answer 19

interrupting rating

Question 20

An OCPD must be able to interrupt destructive fault current energy safely. If a ______ current exceeds a level beyond the OCPD’s capability, it may rupture, causing damage and posing a safety hazard

Answer 20

fault

Question 21

The amperes interruption current (AIC) rating for circuit breakers is _________ A and _________ A for fuses. Circuit breakers and fuses typically have an AIC rating of ________ A.