Random junk Flashcards
What does ELI mean in the saying “ELI the ICE man”
voltage(E) leads current(I) in an Inductive(L) circuit.
What does ICE mean in the saying “ELI the ICE man”
Current(I) leads voltage(E) in a capacitive(C) circuit.
Typical voltage of output of power generation station
11-33 KV
a 35microfarad capacitor is connected to a 120v, 60hz line what is Xc
Hint: Xc=1/(2(pi)(f)(c)
75.79
Most low voltage breaker manufacturers recommend contacts touch within _____ of each other
1/8”
How many resistors in a Wheatstone bridge are variable
1
What range of impedance levels can modern test instruments take during battery fault tracing?
400K ohms
do schematic diagrams show physical location of components
no
When should an arrester be replaced after it has safely vented pressure?
Immediately, if it can no longer protect against venting
Surge arresters rated less than 1Kv must not have grounding conductor smaller than 14 AWG copper or aluminum.
False
is an energized work permit always necessary?
no
Insulating rubber gloves can be cleaned with chemicals?
False
Higher surge arrester ratings are proffered because they have the highest margin of protection for the equipment.
False.
Highest voltage of a nickel based battery
1.2v
Testing of CT’s should verify they cannot be
open circuited
What is anti-pump?
The circuit breaker can only be closed once for an operation of the control switch to the close position.
What insulating material is best rated for dielectric loses.
PE(polyethylene)
What power provides lighting and protection power in power failure.
emergency
rooms with exposed electoral parts are forbidden to all except _________ persons.
qualified
Benefit to transformer core grounding strap?
single point ground
limited approach boundry
unqualified person and anything conductive must be out of this area.
What gas does NOT indicate overheating of a transformer
methane
lead acid battery each cell can have mow many volts
2
What do motor starter blow out coils do
create magnetic filed the draws the arc into the chute
minimum clearance between 600v normally open conductors need to be _____ apart according to NEC.
12”
study electrical theory
seriously do it
isolation transformer all windings will have the same volts per turn?
Yes
Relays in protection scheme are for
sensing
what circuit is not in a typical distribution system?
secondary loop
electrical system where each transformer can be supplied from either of 2 sources is called a
primary selective system.
What test should not proceed with until busway IR levels are above minimum?
Dielectric withstand (Hipot)
training for NFPA 70E is in class or the field?
Either
What measures the charge of a lead acid batery
hydrometer
one test that is NOT required for silicone insulation liquid
interfacial tension.
restricted approach boundary of 69Kv system
3’6”
most common control wiring insulation class
600V.
what insulating liquid has the highest fire point
Silicone
One coulomb per second describes what?
Ampere
What type of diagram is best for troubleshooting?
Schematic
importance of CT’’s
reduces supplied AC for relay applications
a multimode fiber cable spliced with a single node cord will lose power due to diameter difference?
True
A wye-delta transformer has a primary line voltage of 7200 V and a secondary line voltage of 480 V. What is the turns ratio?
8.66:1
(use 7200/1.73 for the calculation. that gets you 4160/480 since the wye winding is included.)
Losses in the core of iron core inductors include _____ and _____ losses.
eddy current, hysteresis
What is the expected torque (pound-feet) value of a 3/8” Grade 5 bolt?
20
What should be done if rubber insulating gloves are contaminated with oil based compounds?
Discard and replace them
The invention of the ____ made long distance transmission lines practical.
transformer
Overcharging of a lead acid battery can produce which gas?
Hydrogen
Calculate the amplitude of a waveform having a peak output of 100V at an angle of 45 degrees.
Vi = Vp*SIN(Angle)
70.71 V
Schematic diagrams should always be drawn with switches and contacts shown in a de-energized position.
True
What does the “Operating Duty Cycle” indicate for a circuit breaker?
The sequence of operations in a specific period and interval.
Which of the following refers to the current a switchboard or protective device can carry continuously without deterioration and without exceeding temperature rise limits?
ampere rating
In an AC circuit, if frequency is increased which of the following is true:
Inductive Reactance increases
Help: XL = (2πfL)
XC = 1 / (2πfC)
In what format are schedules typically expressed in electrical distribution drawings?
Tabular form
When protecting dry-type transformers greater than 1000kVA from voltage spikes, a _____ type arrester is commonly used.
intermediate class
At what IR value does a P.I. test become ambiguous?
Your Answer: 10 Gigohm
5 Gigohm
Choose the best answer that defines: “An organization, office, or individual responsible for enforcing the requirements of a code or standard, or for approving equipment, materials, an installation, or a procedure.”
AHJ (Authority Having Jurisdiction)
When a device equipped with ZSI senses a short circuit or ground fault, it sends a restraint signal to the ZSI device just ______ from it. This activates the preset time delay on the _____ device.
upstream, upstream
Piezoelectricity is caused by _______.
pressure
Inductors resist sudden changes in ____ .
Current
In motors, which of the following relay protection is provided as protection for unbalance in the loading of the machine:
thermal protection
What is the term often used to refer to a concrete-encased electrode?
Ufer ground
In most instances, the arc flash boundary is the __________ of all approach boundaries to the electrical hazard.
outermost
When may circuit breakers be installed in parallel for a single load?
Only when factory assembled
Does the Wheatstone bridge system require an electrical power source?
Yes
According to NFPA 70E, all employees shall be instructed to be alert at all times when they are working within the limited approach boundary of energized electrical conductors, regardless of the operating voltage.
False
What is the calculated MVA rating for a 15kV Vacuum circuit breaker operating at 13.8kV with an interrupting rating of 1600A and a short circuit rating of 25kA?
650
Help: MVA = SC x (Max Voltage x 1.732) / 1,000,000
A watt-hour meter has a watt-hour constant, Kh, of 1.2 it is used with 1200/5 ratio current transformers and 14,400/120 potential transformers. What is the primary watt-hour constant Kh?
34,560
Which factor(s) determine the best thermal imaging camera for an inspection?
The type of equipment and environmental conditions
What is the maximum acceptable leakage current for electrical shock resistant (EH) footwear under dry conditions?
3.0 milliamperes
Why is it essential to have a good understanding of the basic operating principles of each piece of equipment when performing infrared scans?
To recognize abnormal heating patterns specific to individual components
Insulated hand tools are dielectrically tested at ______.
10,000 VAC
When evaluating insulation test results on a medium-voltage, air-magnetic circuit breaker, what quantity is evaluated?
Watts-loss
Two capacitors, a 20 µF and a 30 µF, are connected in parallel to a 400 Hz source. The total capacitive reactance is
7.96 ohms
Electrical system grounding will stabilize the voltage to earth during normal operation.
True
The 50 element will:
Cause a circuit breaker to trip with no intentional delay when current exceeds the pickup level.
An emergency system shall have adequate capacity and rating for ______ to be operated simultaneously.
all loads
Which parameter provides insight into the intensity of the electrical discharges occurring within a cable’s insulation during PD (Partial Discharge) testing?
PD Level
Which option does NFPA 70B define as “a managed program of inspecting, testing, monitoring, analyzing, and servicing electrical systems and equipment with the purpose of maintaining safe operations and production by reducing or eliminating system interruptions and equipment failures?”
Electrical maintenance program
