Module 3 - Introduction to Circuit Protection, Control, and Measurement
Navy Electricity and Electronics Training Series (NEETS)
Chapter 2:  Pages 2-41 through 2-42

A20.

     a. Center connector

     b. Outside connector

A21. Visual inspection, indicators, and using a meter.

A22. Put it back in the circuit. a good fuse will have zero ohms of resistance.

A23. The ohmmeter causes more than 1/500 ampere through the fuse when you check the fuse, thus it opens the fuse.

A24. use a resistor in series with the fuse when you check it with the ohmmeter.

A25. Turn the power off and discharge the circuit before you remove fuses. use a fuse puller (an insulated tool) when you remove fuses front clip-type fuse holders. When you check fuses with a voltmeter, be careful to avoid shocks and short circuits.

A26.

     a. Not acceptable-wrong style

     b. Substitute #3-smaller current rating

     c. Substitute #1-identical, except higher voltage rating

     d. Not acceptable-lower voltage rating

    e. Direct replacement

     f. Not acceptable-higher current rating g. Substitute #2-Faster time delay rating

A27. Check for the proper type of replacement fuse and proper fit.

A28. Be sure the power is off in the circuit and the circuit is discharged before replacing a fuse. use an identical replacement fuse if possible. Remove any corrosion from the fuseholders before replacing the fuses.

A29. Improper fuse, corrosion, improper fit, and open fuse.

A30. Frame, operating mechanism, arc extinguishers, terminal connectors, and trip element. A31. Thermal, magnetic, and thermal-magnetic.

A32. The thermal trip element makes use of a bimetallic element that bends with an increase in temperature or current. The bending causes the trip bar to be moved releasing the latch.

A33. a circuit breaker that will trip even if the operating mechanism is held ON.

A34. a circuit breaker that can be overridden if the operating mechanism is held ON. A35. In current sensitive or nonemergency systems.

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A36. In emergency or essential circuits.

A37. Instantaneous, short time delay, and long time delay.

A38. It is the use of time delay ratings to cause the circuit breaker closest to the faulty circuit to trip.

This isolates the faulty circuit without affecting other circuits.

A39. CB1-long time delay; CB2, CB3-short time delay; CB4 through CB10-instantaneous.

A40. The power requirements of the circuit and the physical space available.

A41. a push button or push-pull circuit breaker (small size, low power).

A42. Check the applicable technical manual, obtain the approval of the electrical or engineering officer (for shipboard circuit breakers), remove power from the circuit breaker, and tag the switch that supplies power to the circuit breaker.

A43. Check the operating mechanism for smooth operation, check the contacts for pitting, check the terminals for tightness and corrosion, check the mounting hardware for tightness and wear, check all components for wear, and check the entire circuit breaker for cleanliness.

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