________ relates to the ability of the protective device to quickly extinguish the arc after the fuse element melts or the circuit breaker opens, and to prevent the open-circuit voltage in the system from restriking across the open fuse element or across the circuit-breaker contacts
Voltage rating
The ________ of a fuse or a circuit breaker must be equal to or greater than the voltage of the circuit or system
Voltage rating
The ________ is the current the device can carry continuously without opening, deteriorating or exceeding prescribed temperature limits
Ampere rating
________ is the maximum short-circuit an overcurrent protective device can safely interrupt without damaging itself
Interrupting rating
________ compare fault magnitude and speed of response
Time-current characteristics
Time-delay fuses must be marked with which letter?
“D”, for delay
Non-time-delay fuses must be marked with which letter?
“P”, for low melting point
Besides instances where current exceeds a fuse’s current rating, a fuse may occasionally open under what circumstances?
High ambient temperatures, as well as loose or dirty connections, may cause the fuse to trip
A ________ is a simple device that protects the conductor of a circuit
Fuse
A ________ is an insulated tube containing a strip of heat-sensitive metal that has a lower melting point than copper or aluminum
Fuse
The ________ is sometimes called the screw-base or Edison-base fuse
Plug fuse
What are the 4 ratings/characteristics one should observe when replacing a fuse?
Voltage rating, current rating, interrupting-capacity rating, and time-current characteristic
The maximum rating of any plug fuse is ________
30A
What are the two non-interchangeable plug fuse types?
Type C and type S fuses
________ are manufactured in ferrule-contact, knife, and bolt-on styles
Cartridge fuses
The ________ is designed to be the weakest link in the circuit. Its job is to break the circuit before damage is done to the conductors
Fuse
Some fuses come with ________, which helps extinguish the arc during a short circuit
Arc quenching powder
The ________ consists of two fuse links joined by a thermal cutout unit connected in series
Time-delay fuse
________ interrupt large short-circuit currents without disintegrating
High-rupturing capacity (HRC) fuses
Name the two categories of HRC fuses and list their characteristics
HRCI and HRCII. HRCI fuses provide protection from both overloads and short circuits and have a high interrupting capacity of 200,000A. HRCII fuses provide short-circuit protection only. If used in a motor for over-current protection, an overload device must also be installed
