Practical values of power factor: Difference between revisions

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The calculations for the three-phase example above are as follows:
 
Pn = delivered shaft power = 51 kW<br>
P = active power consumed
 
<math>P=\frac {Pn}{\rho}=\frac{51}{0.91}=56\, kW</math>
 
S = apparent power
 
<math>S=\frac{P}{cos \phi}=\frac {56}{0.86}= 65\, kVA</math>
 
So that, on referring to diagram '''Figure L5''' or using a pocket calculator, the value of tan <span class="texhtml">φ</span> corresponding to a cos <span class="texhtml">φ</span> of 0.86 is found to be 0.59
 
Q = P tan <span class="texhtml">φ</span> = 56 x 0.59 = 33 kvar
 
Alternatively:
 
<math>Q=\sqrt{S^2 - P^2}=\sqrt{65^2 - 56^2}=33\, kvar</math>
 
 
[[Image:FigL05.jpg|none]]
'''''Fig. L5:''''' ''' Calculation power diagram'''
 
 
 
 
== Average power factor values for the most commonly-used equipment and appliances ==
== Average power factor values for the most commonly-used equipment and appliances ==
(see '''Fig. L6''')
(see {{FigRef|L7}})


 
{{tb-start|id=Tab1331|num=L7|title=Values of cos φ  and tan φ for commonly-used equipment|cols=4}}
{| style="width: 774px; height: 418px" cellspacing="1" cellpadding="1" width="774" border="1"
{| class="wikitable"
|-
! colspan="4" | Equipment and appliances  || cos φ  || tan φ
|-
| rowspan="5" | Motor
| rowspan="5" |Common induction motor
| rowspan="5"| loaded at  || 0 %  || 0.17  || 5.80
|-
| 25%  || 0.55  || 1.52
|-
| 50 %  || 0.73  || 0.94
|-
| 75 %  || 0.80  || 0.75
|-
| 100 %  || 0.85  || 0.62
|-
| rowspan="4" |Lamps
| colspan="3" |Incandescent lamps 
| 1.0  || 0
|-
| colspan="3" |Fluorescent lamps (uncompensated) 
| 0.5  || 1.73
|-
| colspan="3" |Fluorescent lamps (compensated)
| 0.93  || 0.39
|-
| colspan="3" |Discharge lamps 
| 0.4 to 0.6  || 2.29 to 1.33
|-
| rowspan="3" |Ovens
| colspan="3" |Ovens using resistance elements
| 1.0  || 0
|-
| colspan="3" |Induction heating ovens (compensated) 
| 0.85  || 0.62
|-
|-
| bgcolor="#0099cc" colspan="3" | '''Equipment and appliances'''
| colspan="3" |Dielectric type heating ovens
| bgcolor="#0099cc" | '''cos φ'''
| 0.85  || 0.62
| bgcolor="#0099cc" | '''tan φ'''
|-
|-
| valign="top" |  
| rowspan="4" |Welding
*Common induction motor
| colspan="3" |Resistance-type soldering machines
 
| 0.8 to 0.9  || 0.75 to 0.48
| valign="top" | loaded at
| valign="top" |
0%
 
25%
 
50%
 
75%
 
100%
 
| valign="top" |
0.17
 
0.55
 
0.73
 
0.80
 
0.85
 
| valign="top" |  
5.80
 
1.52
 
0.94
 
0.75  
 
0.62
 
|-
|-
| valign="top" |  
| colspan="3" |Fixed 1-phase arc-welding set
*Incandescent lamps
| 0.5 || 1.73
*Fluorescent lamps (uncompensated)
*Fluorescent lamps (compensated)
*Discharge lamps
 
| valign="top" | &nbsp;
| valign="top" | &nbsp;
| valign="top" |
1.0<br>0.5<br>0.93<br>0.4 to 0.6
 
| valign="top" |  
0<br>1.73<br>0.39<br>2.29 to 1.33
 
|-
|-
| valign="top" |  
| colspan="3" |Arc-welding motor-generating set
*Ovens using resistance elements
| 0.7 to 0.9  || 1.02 to 0.48
*Induction heating ovens (compensated)
*Dielectric type heating ovens
 
| valign="top" | &nbsp;
| valign="top" | &nbsp;
| valign="top" |  
1.0<br>0.85<br>0.85
 
| valign="top" |  
0<br>0.62<br>0.62
 
|-
|-
| valign="top" |  
| colspan="3" |Arc-welding transformer-rectifier set
*Resistance-type soldering machines
| 0.7 to 0.8 || 1.02 to 0.75
*Fixed 1-phase arc-welding set
*Arc-welding motor-generating set
*Arc-welding transformer-rectifier set
 
| valign="top" | &nbsp;
| valign="top" | &nbsp;
| valign="top" |
0.8 to 0.9<br>0.5<br>0.7 to 0.9<br>0.7 to 0.8
 
| valign="top" |  
0.75 to 0.48<br>1.73<br>1.02 to 0.48<br>1.02 to 0.75
 
|-
|-
| valign="top" |  
| colspan="4" |Arc furnace
*Arc furnace
|0.8
 
|0.75
| valign="top" | &nbsp;
| valign="top" | &nbsp;
| valign="top" | 0.8  
| valign="top" | 0.75
|}
|}
'''''Fig. L6:'''''<i>&nbsp;Values of cos <span class="texhtml">φ</span> and tan <span class="texhtml">φ</span> for commonly-used equipment</i><br>
[[ru:Практические значения коэффициента мощности]]
[[zh:功率因数的实际值]]

Latest revision as of 09:49, 22 June 2022

Average power factor values for the most commonly-used equipment and appliances

(see Fig. L7)

Fig. L7 – Values of cos φ and tan φ for commonly-used equipment
Equipment and appliances cos φ tan φ
Motor Common induction motor loaded at 0 % 0.17 5.80
25% 0.55 1.52
50 % 0.73 0.94
75 % 0.80 0.75
100 % 0.85 0.62
Lamps Incandescent lamps 1.0 0
Fluorescent lamps (uncompensated) 0.5 1.73
Fluorescent lamps (compensated) 0.93 0.39
Discharge lamps 0.4 to 0.6 2.29 to 1.33
Ovens Ovens using resistance elements 1.0 0
Induction heating ovens (compensated) 0.85 0.62
Dielectric type heating ovens 0.85 0.62
Welding Resistance-type soldering machines 0.8 to 0.9 0.75 to 0.48
Fixed 1-phase arc-welding set 0.5 1.73
Arc-welding motor-generating set 0.7 to 0.9 1.02 to 0.48
Arc-welding transformer-rectifier set 0.7 to 0.8 1.02 to 0.75
Arc furnace 0.8 0.75
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