competence 7

27問 • 1年前

問題一覧

When a megohmmeter is being used to test insulation resistance, current leakge along the surface of the insulation is indicated by the megohmmeter's pointer ?

kicking slightly down scale as voltage is applied

In using the Rheostat, what do you call the circuit of the motor to adjust the speed?

Induction motor with wound-rotor

How can you restor the charge of a lead-acid battery?

passing a direct electric current through the cell

In an impressed current cathodic protection system, what is anode

insulated from the hull and does not waste away

Complete maintenance of electrical motors should inlcude periodic checks for machine

vibration

The automatic voltage regulators provide on switch boards has function to

vary the field excitation to the generators

If a delicate component must be soldered into a circuit the component may be protected from the heat of the soldering process by

using a thermal shunt

What maximum voltage can Class 00 electrical insulating rubber gloves can be used

500 volts

Which of the following statements represents the FIRST step in seating new brushes on slip rings?

Lay sandpaper between the brush and the slip ring and slide the sandpaper back and forth under the brush

Which of the following statement is true concerning the cleaning electrical contacts?

Delicate parts should be cleaned with a brush and an approved safety solvent

What indicates the third color band on a resistor ?

number of zeros following the first two significant figures in the resistance value

What should indicate ground in a particular phase 3- phase low voltage distribution system ?

dark or dim switchboard ground detecting light

While trouble shooting a circuit in an engine room central control console, a resistor is suspected of being faulty. Which of the following precautions must be observed if an ohm meter is to be use to check its value?

Resistor circuit must be de-energized and at least one end of the component isolated

Which of the following statements best describes teh material known as varnished cambric?

Cotton cloth coated with insulating varnish

What is the first step to properly use a hook-on-type voltammeter in checking current flow?

hook the jaws of the instruments around the insulated conductor

Upon failure of the normal power supply, the emergency generator is place on the line by the

automatic bus transfer devise

Where a thermal-acting breaker is required to be used in an area of unusually high, low or constantly fluctuating temperatures, an ambient compensating element must be used. What does this element consist of ?

second bimetal element

Which of the listed precautions should be observed before spraying liquid solvent on the insulation of an electric motor?

Disconnect the motor from the power source

The electrolyte in alead-acid storage battery consists of distilled water and

sulfuric aced

The insulation ersistance of electric equipment and machinery should be tested for lowest normal insulation valves

immediately after shutting down of the machine

How much is the typical resistance of the body from hand to foot when dry?

500 ohm

How will you remove a tubular fuse from a fuse panel with?

fuse puller

Which of device taht commonly utilizes the principle of electromagnetic induction?

transformer

When a lead-acid battery begins gassing freely while receiving a normal charge, what should you do when charging?

be decreased

In the circle diagram for induction motor, the diameter of the circle represents

rotor current

What is a three-layer bidirectional device used primarily as a triggering device with junctions heavily and equally doped?

Diac

Two contributors of electronic console failures are heat and vibration. To combine some of their effect, preventive maintenance procedures include

periodic changing or cleaning of console ventilation and control room air conditioning filter

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