Low-voltage Breakers

Question 1

Circuit breakers provide___ for generators, transformers, motors and distribution circuits.

Answer 1

Control and protection

Question 2

Which of the following is the term given to the process of engaging and disengaging the primary contacts of the breaker with the incoming bus in the load?

– Racking
– latching
– tripping
– closing

Answer 2

Racking

Question 3

Which of the following is the voltage range of a low voltage breaker?

– 600 V to 69 KV
– less than 600 V
– more than 50 KV
– 50 KV to 100 KV

Answer 3

Less than 600 V

Question 4

What does a thermal circuit breaker are used to sense fault current?

Answer 4

Thermal element

Question 5

And electric arc is formed when current flow is ___.

Answer 5

Interrupted

Question 6

Inside the housing the MCCB contains a tripping element which is made out of one of the following materials EXCEPT:

– Magnetic
– thermal
– hydraulic
– ceramic

Answer 6

Ceramic

Question 7

Thermal element breakers need time after a fault to ___.

Answer 7

Cool

Question 8

Air circuit breakers use arcing contacts to draw the arc up into ___ to extinguish it.

Answer 8

Arc chutes

Question 9

Finger clusters on the back of the breaker in gauge the ___ of the large frame circuit breaker to the incoming bus and load.

Answer 9

Primary contacts

Question 10

A smaller stab connection block connects the circuit breaker ___ to control power and the auxiliary devices.

Answer 10

Secondary contacts

Question 11

Similar to the MCCB, the ICCB will trip with no intentional delay in the presence of ___ that exceeds either instantaneous pick up or instantaneous override settings.

Answer 11

High magnitude current

Question 12

Thermal element breakers need time after a fault trip to ____..

Answer 12

Cool

Question 13

___ use arcing contacts to draw the arc up into arc chutes to extinguish it.

Answer 13

Air circuit breakers

Question 14

___ is the term given to the process of engaging and disengaging the external primary contacts of the breaker with the incoming bus and the load.

Answer 14

Racking

Question 15

Molded case breakers have a spring loaded ____ between the operating handle and a contact closing mechanism that ensures a quick make or break of the contacts.

Answer 15

Linkage

Question 16

Which of the following is NOT a way that circuit breakers control current flow?

– Closing to energize distribution circuits and start motors
– Tripping open when given the open command
– Tripping open in the event of a fault or abnormal condition
– Tripping open to energize distribution circuits and start motors

Answer 16

Tripping open to energize distribution circuits and start motors

Question 17

What does a thermal circuit breaker use to sense fault current?

Answer 17

Thermal element

Question 18

An electric arc is formed when current flow is ___.

Answer 18

Interrupted

Question 19

A small stab connection block connects the circuit breaker ___ to control power and the auxiliary devices.

Answer 19

Secondary contacts

Question 20

___ on the back of the breaker in back the primary contacts of the large frame circuit breaker to the incoming bus and load.

Answer 20

Finger clusters

Question 21

What is the voltage range of a low voltage breaker?

Answer 21

Less than 600 V

Question 22

Circuit breakers provide ___ for generators, transformers, motors and distribution circuits.

Answer 22

Control and protection

Question 23

The magnetic trip of a molded case circuit breaker is provided by a current transformer and a ____.

– Trip coil
– tension coil
– torsion coil
X solenoid

Answer 23

? Unknown