more im diagrams

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Peter 2022-10-27 01:10:00 +08:00
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etc/

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README.md
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> Why are the drawings bad?
I draw them with a mouse
### Types of power factors (From `ENSC2003`)
Where $\bar{S}=|\bar{S}|\angle\varphi$:
$$ \varphi = \arctan\left(\frac{Q}{P}\right) = \theta_v-\theta_i$$
| | Lagging | Leading | Unity |
| ----------- | -------------- | ------------- | ------------ |
| Voltage | Current behind | Current ahead | In phase |
| Load type | Inductive | Capacitive | Resistive |
| $Q$ | $Q>0$ | $Q<0$ | $Q=0$ |
| $\varphi$ | $\varphi>0°$ | $\varphi<0°$ | $\varphi=0°$ |
| PF [Load] | $[0,1)$ | $[0,1)$ | $1$ |
| PF [Source] | $[0,-1)$ | $[0,-1)$ | $-1$ |
## Power types in motor
| Type | Description | Equivalent terms |
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\end{align}
$$
## No-load test
Note - assume loss is 0 if not mentioned!
| Assumption | Eqn | Reason |
| ------------------------------ | ----------------- | ------------------------------ |
| rotor current is insignificant | $I_r \approx 0$ | high rotor resistance |
| no output mechanical power | $P_\text{out}=0$ | no load |
| high rotor resistance | $R_r/s\to \infty$ | $s\to 0$, high slip at no load |
| Type | Description | Symbols |
| ------------------------- | ------------------------------------------- | --------------------------------------- |
| Load torque, Shaft torque | Torque experienced by load after all losses | $\tau_\text{load}$, $\tau_\text{shaft}$ |
## $3\phi$ induction motor
### Etc.
- Slip speed $N_\text{slip}=N_{s\text{ (sync)}}-N_r=sN_{s\text{ (sync)}}$
- "1/4 of rated load" != "1/4 times full load"
- Means 1/4 of full load slip as it is in the linear region. Accounts for the minimum load.
- Rated power stated in machine specification refers to the output power $P_\text{out}$, and excludes all losses.
- Speed regulation using machine speed: $$\text{SR}=\frac{N_{r,\text{NL}}-N_{r,\text{FL}}}{N_{r,\text{FL}}}$$
### Diagram
![](2022-10-26-22-06-19.png)
### Equivalent model
#### Assumptions
- $x_m\approx X_m$
- $R_c\ggg X_m\Rightarrow r_c\lll x_m$
- $x_m=\frac{{R_c}^2}{{R_c}^2+{X_m}^2}X_m\approx\frac{\cancel{{R_c}^2}}{\cancel{{R_c}^2}}X_m=X_m$
- $r_c\approx {X_m}^2/R_c$
- $R_c\ggg X_m\Rightarrow r_c\lll x_m$
- $r_c=\frac{{X_m}^2}{{R_c}^2+{X_m}^2}R_c\approx\frac{{X_m}^2}{{R_c}^2}R_c=\frac{{X_m}^2}{R_c}$
### Diagram
![](2022-10-26-21-53-13.png)
### DC test
#### $\Delta$ machine
$$R_s=\frac{3}{2}\cdot\frac{V_{\text{DC},3\phi}}{I_{\text{DC},3\phi}}$$
![](2022-10-26-22-43-25.png)
#### Y machine
$$R_s=\frac{1}{2}\cdot\frac{V_{\text{DC},3\phi}}{I_{\text{DC},3\phi}}$$
![](2022-10-26-22-48-09.png)
### No-load test
#### Assumptions
- $P_\text{out}=0$
- No output power as no load.
- $R_r/s=\infty$ and $I_r=0$
- Infinite rotor resistance, ignore rotor path.
#### Diagram
Using assumptions, remove rotor part of circuit and only consider stator and magnetizing path.
![](2022-10-25-11-45-26.png)
## Blocked rotor test
### Blocked rotor test
| Assumption | Eqn | Reason |
| ----------------------- | ---------------------------------- | ------------------------------------------------------------------------------- |
| ignore magnetizing path | $I_r\ggg I_m$ | magnetizing current is low compared to rotor current as rotor resistance is low |
| low rotor resistance | $R_r/s\approx R_r$ | $s\approx 1$, slip is $1$ when blocked |
| | $X_r\approx f_0/f_{BL}\times X_r'$ | $X_r'\approx X_{BL}/2$ |
| | $X_r'\approx X_{BL}/2$ | $X_s\approx X_r'$ |
| | $X_s\approx X_r'$ |
#### Assumptions
- Ignore magnetizing path, $I_m=0$
- $I_r\ggg I_m$ as $R_r/s\ggg Z_m$
- $R_r/s=R_r$, $s=1$
- Slip is $1$ as rotor is blocked.
- $x_s=x_r'$
- Same number of turns in stator and rotor
- and $x_r=f_0/f_\text{BL} \times x_r'$
- Note: $x_r'$ is the inductance at $f_\text{BL}$, the blocked rotor test frequency which is less than the nominal frequency $f_0$
#### Diagram
Ignore magnetizing path
![](2022-10-25-11-46-04.png)
## Equivalent model
---
| Assumption | Eqn | Reason |
| ---------- | ------------------------ | ------------------------------------ |
| | $x_m\approx X_m$ | $R_c\ggg X_m\Rightarrow r_c\lll x_m$ |
| | $r_c\approx {X_m}^2/R_c$ | $R_c\ggg X_m\Rightarrow r_c\lll x_m$ |
## Single-phase induction motor
### Diagram
![](2022-10-26-21-47-29.png)
### Blocked-rotor
#### Diagram
![](2022-10-26-21-48-00.png)
### No-load
#### Diagram
![](2022-10-26-21-47-49.png)