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NAVEDTRA 14175A
CIRCUIT PROTECTION, CONTROL, AND MEASUREMENT
Question | Answer |
---|---|
What is used to monitor the operation of an electrical or electronic device, or to determine the reason a device is not operating properly? | circuit measurement |
Which type of meter is used to monitor the operation of the device in which it is installed? | in-circuit |
What is the process of locating and repairing faults in equipment after they have occurred? | troubleshooting |
Which type of meter can be used wherever you wish to connect it? | out-of-circuit |
Which type of instrument measures small amounts of current and is based on the electromagnetic principle? | Galvanometer |
Which device changes alternating current to a form of direct current? | rectifier |
What is the process of "smoothing out" the oscillation of the pointer? | damping |
Which type of meter movement is the most commonly used movement for AC meters? | moving-vane |
Which type of meter consists of a resistance wire across the meter terminals which heats in proportion to the amount of current? | Thermocouple |
Which type of device is used to measure current? | ammeter |
Connecting an ammeter in what way would give you not only an incorrect measurement, it would also damage the ammeter, because too much current would pass through the meter? | parallel |
What is the amount of current necessary to cause full scale deflection (maximum reading) of the ammeter? | ammeter sensitivity |
Most meter movements in use today have sensitivities from 5 microamperes to what? | 1 miliampere |
What is a resistor called that is in parallel with meter movement? | shunt resistor |
In what way must ammeters always be connected with the circuit under test? | series |
How are voltmeters always connected? | parallel |
What formula can be used to calculate voltage if the current and resistance are known? | E=IR |
How is voltmeter sensitivity expressed? | Ohms per volt |
What device is widely used to measure resistance and check continuity of electrical circuits and devices? | Ohmmeter |
Which device is widely used for measuring insulation resistance? | Megger |
The range of a megger may extend to more than how many megohms? | 1,000 |
How many volts are Navy meggers usually rated at? | 500 volts |
What is the most common measuring device used in the Navy? | Multimeter |
Which type of meter movement do most multimeters use? | D'Arsonval |
What is used to measure electric power? | Wattmeter |
What is energy the product of? | power and time |
What type of frequency meter is one of the simplest devices for indicating the frequency of an AC source? | Vibrating-reed |
Moving-disk frequency meters are most commonly what type of meters? | out-of-circuit |
What are used to measure resistance and to check continuity? | Ohmmeters |
Which single meter combines the function of a dc ammeter, a dc voltmeter, an ac ammeter, an ac voltmeter, and an ohmmeter? | Multimeter |
What is the application and removal of power in its simplest form? | circuit control |
Most circuit control devices are either switches, solenoids, or what else? | relays |
Which type of switch is controlled by a person? | manual |
Which type of switch is controlled by a mechanical or electrical device? | automatic |
Multi-contact switches are usually classified by the number of poles and number of what? | throws |
Which type of switch is a mid-contact switch part of the schematic with the contacts arranged in a full or partial circle? | rotary |
Which term means that the switch will only remain in the momentary position as long as the actuator is held in that position? | momentary |
Which type of switch is a switch in which the movement of the switch mechanism (contacts) is relatively independent of the activating mechanism movement? | snap-acting |
What is the accurate snap-acting switch commonly called? | microswitch |
Which switch property refers to the maximum current the switch is designed to carry? | current rating |
Which switch property refers to the maximum voltage allowable in the circuit in which the switch is used? | voltage rating |
How many or more times without failure are most switches designed to operate if the voltage and current ratings are not exceeded? | 100,000 |
What is a control device that uses electromagnetism to convert electrical energy into mechanical motion? | solenoid |
What is produced from current flowing through a conductor? | magnetic field |
What is the first step for troubleshooting a solenoid? | visual inspection |
What are electrically operates control switches? | relays |
What are power relays referred to as? | contactors |
What problem may be created at the contacts when current flows in one direction through a relay? | cone and crater |
What type of tool is used to clean the contacts of a relay? | burnishing tool |
What tool is used to adjust contact spacing of a relay? | point bender |