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37 Cards in this Set
- Front
- Back
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What is 0.7071 times the zero-to-peak value of the sine wave?
(9-2) |
RMS value |
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What IEEE standards discusses harmonics? |
IEEE 519 |
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What is the method for connecting the secondary or primary windings of a transformer in a common point?
(9-3) |
Wye |
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What is the method for connecting the secondary or primary windings of a transformer in Series?
(9-3) |
Delta |
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What is accomplished when the time required to complete one cycle is divided into 360 degrees?
(9-4) |
Phase difference measuring |
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What is the portion of the impedance that opposes a change in current flow because of magnetic field coupling?
(9-9) |
Inductive Reactance (Xl) |
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What is the portion of the impedance that opposes a change in current flow because of electric field coupling?
(9-9) |
capacitive reactance (Xc) |
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Apparent power is expressed in:
(9-11) |
VA - volt-amperes |
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Real power is expressed in:
(9-11) |
watts |
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Voltage leads current in what kind of circuit?
(9-10) |
Inductive circuit |
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Current leads voltage in what kind of circuit?
(9-11) |
Capacitive circuit |
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The ratio of real power to apparent power is called:
(9-12) |
Power Factor |
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Sags and Swells have a duration of:
(9-20) |
0.5 cycles to one minute |
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Overvoltage and undervoltage have durations of:
(9-20) |
More than 3600 cycles (one minute) |
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What does IEEE 519 set as the maximum allowable THD of the voltage waveform?
(9-21) |
5 percent |
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What generally causes harmonics?
(9-21) |
Solid state components and electronic ballasts |
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True or False: it is not recommended that voice and data equipment utilize Isolated Ground systems.
(9-22) |
True |
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True or False: Dedicate branch circuit are recommended for telecommunications systems for each type of equipment served.
(9-22) |
True |
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Where neutral is considered a current carrying conductor, it may carry 173 percent more current than a phase conductor. What should be neutral be sized to?
(9-24) |
200 percent neutrals |
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What do K-ratings of transformers imply?
(9-25) |
they tell the transformers ability to dissipate heat caused by harmonics |
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What is the load makeup when a K-13 transformer is used?
(9-25) |
75% Non-linear, 25% Linear |
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What is the load makeup when a K-20 transformer is used?
(9-25) |
100% Non-linear |
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What is the maximum length of ITE power cords?
(9-28) |
15 feet |
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What is N+2 Redundancy?
(9-37) |
provides two additional complete units, modules, paths or systems, in addition to the base requirements |
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What is a shielded isolation transformer?
(9-44) |
Similar to an isolation transformer, but also includes a grounded electrostatic shield between the windings |
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SPD installation leads should be kept to a minimum, not to exceed how many inches?
(9-45) |
12 inches |
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What UPS topology is usually reserved for large critical facilities?
(9-61) |
A ring bus UPS topology |
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What is the nominal voltage for a DC telecommunications system operating in the US?
(9-62) |
negative 48V; because the positive side is intentionally grounded |
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What is the nominal voltage for a DC Radio system operating in the US?
(9-62) |
Positive 24V |
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Why are power calculations on a DC system simpler?
(9-66) |
No Power Factor |
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What it the bend radius for unshielded power cable?
(9-74) |
eight times the overall diameter |
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Batteries do not store electricity; what do they store? |
energy in chemical form |
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What is the recommended number of air changes for a room with gassing batteries?
(9-76) |
minimum of four air changes |
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What is required for battery sizing?
(9-79) |
1. DC required in amperes at minimum voltage
2. DC input window of load
3. Operating temperature of battery
4. Battery back up time required |
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What is the maximum number of battery cells that should be paralleled in a battery plant?
(9-82) |
five |
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What is the optimum temperature for a battery?
(9-82) |
77 degree F (25 degree C) |
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What is the minimum working space from live parts in battery racks and cabinets?
(9-83) |
3.3 feet (1 meter) |
