EEE20005 exam study mistakes

magnetic flux is _____ on each side of a magnetic circuit

the same

when does maximum transformer efficiency occur?

when Pcore = Pcu

what are the equations for Pcore and Pcu in a transformer?

Pcore = V1²/Rc | Pcu = Ip² Req

what is the equation for transformer input voltage?

V1 + Zeq*Ip(angle theta)

How is Pconv related to Pout and Prot in an induction motor?

Pconv = Pout + Prot

what are 2 ways of finding Pconv in a DC machine?

Pconv = EaIa = tind*wm

how are Istart and Pin calculated in a DC machine?

Istart = Vt/Ra1 | Pin = Vt * IL

how is the internal voltage of a synchronous machine calculated?

Vphase + (jXs + Ra)*Ia

what is the peak of a sin AC waveform?

sqrt(2) * Vrms

what are the steps for graphing SCR and load voltage?

first draw sin waveform, SCR voltage is 0 in the positive sections (except firing angle), load voltage is the opposite of SCR

for a wound rotor induction motor:

how is line current I_L calculated?

Vphi/(R1 +jX1 + RF +jXF)

for a wound rotor induction motor:

how is R_F + jX_F calculated?

1/((1/jXm) + (1/(R2 + R2((1-s)/s) + X2)))

for a wound rotor induction motor:

how is rotor power factor calculated?

arctan(X2/(R2/s))

for a wound rotor induction motor:

how are stator copper losses (P_SCL) calculated?

3Ia²*R1

for a wound rotor induction motor:

how is air gap power (P_AG) calculated?

3Ia²*Rf

for a wound rotor induction motor:

how is power converted (P_conv) calculated?

(1-s)Pag

for a wound rotor induction motor:

how is output power calculated?

Pout = Pconv - Pmech - Pcore - Pmisc

for a wound rotor induction motor:

how is input power (P_in) calculated?

3Vphi*Ia*cos(theta)

for a wound rotor induction motor:

what is the difference between starting conditions, and non-starting conditions?

for starting conditions, remove the R2((1-s)/s) resistor

for a DC machine:

how is armature current found at full load?

Ia = IL - If

for a DC machine:

what is another way of expressing If ?

Vt/(Radj + Rf)

for a DC machine:

how can E_A be expressed?

Vt - IaRa

for a DC machine:
what does no load imply about V_A and E_A

they are equal

for synchronous machines:

how is Z_base calculated?

(3*Vphi(base))²/S(base)

for a synchronous machine:

how are I_A and I_L calculated?

S/(sqrt(3)*Vt)

for a synchronous machine:

how is P_out calculated when there are no losses?

s*S

for a full-wave rectifier:

How is I_{D, av} calculated?

VL(max)/(pi*RL)

for a full-wave rectifier:

what is I_{max, D} equal to?

the maximum load current

for a full-wave rectifier:

How is I_{rms, D} calculated?

VL(max)/2RL

When a magnetic circuit has 3 legs, how can the flux in each leg be found?

the flux in the leg with the winding it the total flux
the other 2 are found with the flux divider rule

for an induction motor:

how is n_slip calculated?

s*nsync

for a DC machine:

_______ speed occurs at maximum V_A and R_adj

maximum

for a DC machine:

_______ speed occurs at minimum V_A and R_adj

minimum

synchronous machine poles must be ____

even

for a transformer:

how is the kVA rating calculated?

(Nse + Nc)/Nse * S

how can a delta load be converted to Y?

divide it by 3

for a transformer:

how is primary voltage referred to the secondary side (V_p’) calculated?

Vs + (Req + jXeq) * Is

for a transformer:

how is P_cu calcuted?

(Is)² * Req

for a transformer:

how is P_core calculated?

(V_p’)²/Rc

for a synchronous machine:

how is the full-load power calculated?

s * S

for a synchronous machine:

what angle does maximum possible power occur?

90 degrees

for a transformer:

how is maximum current calculated?

S/V

for a synchronous machine:

how is P_in calculated when losses are known?

Pout + Pcu + Pf&w + Pcore + Pstray

for a synchronous machine:

how is Pcu calculated

3 * Ia² * Ra