PHEP 17 Flashcards Preview

RWD OP 1ST 6 MONTHS > PHEP 17 > Flashcards

Flashcards in PHEP 17 Deck (34)
Loading flashcards...
1

What best defines a cycle

two alternations, one in each direction

2

How many times larger is the max voltage value than the effective voltage value

0.707

3

what is another name for effective values

root mean square value

4

Does an AC amp produces heat at the same rate as a DC amp

yes

5

what is the direction of a vector indicated by

a line segment and arrow

6

what is the magnitude of a vector indicated by

length of line

7

in what direction is positive rotation of a vector

counter clockwisewha

8

what effect does self induced voltage have on applied voltage

it opposes it and reduces effectiveness

9

what variables determine inductive reactance

2pi constant, frequency, inductance

10

what is the relationship between current and applied voltage in a purely inductive circuit

current lags 90 degrees

11

What are the two factors that limit current in an inductive circuit?

inductive reactance and resistance

12

in a purely inductive reactant and resistant circuit what is the current applied voltage relationship

current lags by 45 degrees

13

what are the units of capacity

farrads

14

what is power factor

ratio of true power to apparent power

15

AC meters and instruments are designed to read _____ voltage and currents.

Effective.

16

The effective values of voltage and current are equal to the maximum values multiplied by?

.707

17

The three factors that limit the flow of current in an AC circuit are?

1. Resistance
2. Inductive reactance
3. Capacitive reactance

18

In a pure resistance circuit, voltage and current are?

In phase.

19

In an AC circuit, what represents total Opposition to current and what is the symbol?

Impedance, Z

20

What is the symbol for inductive reactance?

XL

21

Whats used to determine inductive reactance?

The frequency and the amount of inductance in a circuit.

22

What does ELI ICE represent?

ELI= voltage leads current (inductance)
ICE= current leads voltage (capacitve)

The letters represent the symbols for voltage, current, inductance, capacitance.

23

Whats the relationship of voltage and current in a pure inductive circuit?

Voltage leads current by 90 degrees.

24

Capacitive reactance varies inversely with?

The frequency and the size of the capacitor.

25

In a pure capacitive circuit, voltage and current's relationship is?

out of phase 90 degrees, with current leading.

26

What does VARs stand for?

Volt-ampere-reactive

27

The power factor is equal to the cosine of the?

angle of phase difference between voltage and current.

28

What is the measurement of the primary harmonic?

60hz

29

What increments do harmonics go by?

60

30

How can you reduce the third harmonic?

By connecting a set of winding's in a transformer in delta.