Book #9 Flashcards
Which voltage value does a DC voltmeter read?
Average value
When testing an unmarked step down transformer using an ohmmeter the:
Secondary winding will have the lower resistance
In a commercial unit, if half the lights suddenly go bright and the other half go very dim, what is the probable cause?
Broken and faulty neutral
When installing electrical equipment using scaffolding 10m high, what is required?
Safety fall-arrest harness
When installing a short-delay timer on a fridge compressor, what is the timers purpose?
Control the duty cycle
How is voltage controlled while maintaining the frequency of an ac generator?
Change the speed of the prime mover
How do you increase speed of a three phase alternator?
Increase the prime mover
Which instrument is used to check di-electric stress of a high voltage cable after installing a stress cone?
Hi-pot
When installing a motor in a high ambient temperature room, what type of overload protection is required?
Magnetic
Which is not a common method of starting polyphase squirrel-cage induction motors?
Capacitive starting
Which is a common ferrous material?
Steel
The shunt winding of a cumulative motor allows for constant-speed control by using:
Smaller wire with many turns
An AC three-phase wound rotor induction motor has:
High starting torque and low starting current
What is the proper angle for setting up a portable extension ladder?
1 foot out for every 4 feet up
The range of a ammeter may be extended by the use of a:
shunt in parallel
The programming of an automated system will drop out all non-critical loads:
Upon loss of voltage
What is the minimum length of the test when performing a cable hi-potting test using 500v DC?
60s
Carbon deposits are found on some electrical contacts during troubleshooting. what does this indicate?
Contacts have been subject to arching
What does the interrupting rating of a circuit breaker indicate?
The maximum short circuit condition the circuit breaker can interrupt safely
In a DC machine, where shall the brushes be located to minimize armature reaction?
Electrical neutral plane
When equipment is not guarded by locked doors, elevation or other means, then it shall be considered
Accessible
When a thermostat calls for heat in a hot water heating system within an apartment, it is in direct control of the:
Zone valve
When terminating a high voltage stress cone, what type of terminal lug is required?
Barrel lug
When does an automated building management system shed non-critical loads?
When the system reaches a preset maximum amount of load
When a motor needs to be replaced, what will be used to determine the physical size of the new motor?
Frame
Upon loss of voltage in one phase to a UPS system, the disconnecting means shall:
Automatically disconnect all phases from the interconnected system
A nylon sling becomes frayed. what you should you do?
Destroy the sling
When a belt breaks in a four belt āVā configuration, what should you do?
Replace with match set of belts
Which of the following electrical systems require ground fault detection
3-phase, 600v
What is the purpose of reduced voltage starting for a DC motor?
Decrease current in the armature windings
