Monitor Type A:

Uses "Volt x Current" (VA) to calculate the cost of electricity. "VA" stands for Volt-Amps and is called "apparent power".

Based on accurate measurements of Volt & Current.

Monitor Type B:

Uses Current only to calculate a false KWh value and false cost of electricity. Its calculations assume a voltage of 120V (or 240V both phases). This example is based on an actual line voltage of 114V (or 228V for both phases).

Assuming an accurate measurement of Current.

Monitor Type C:

Uses "Volt x Current x PF" (Watt) for calculation of cost of electricity. The electrical term is "true power". Other equivalent terms are "Real Power" or "True RMS Power".

Based on accurate measurements of Volt & Current.  Note: PF stands for Power Factor

Expected "Displayed Cost" of Electricity based on the type of "electricity" measured.

Power

Factor 

% Error Using "Apparent Power"

Monitor Type A

Monitor Type B

Monitor Type C

Expected "Displayed Cost" of Electricity for $1.00 worth of power charged by the Power Company.

0.99

1.01%

$1.01

$1.06

$1.00

Compact Fluorescent Bulb

0.63

58.73%

$1.59

$1.67

$1.00

Compact Fluorescent Light 

0.59

69.49%

$1.69

$1.78

$1.00

Light Dimmer   

0.73

36.99%

$1.37

$1.44

$1.00

Electronic Ballast 

0.63

58.73%

$1.59

$1.67

$1.00

Vacuum Cleaner 

0.98

2.04%

$1.02

$1.07

$1.00

Portable Heater       

1.00

0.00%

$1.00

$1.05

$1.00

House Fan ( High Speed )

0.80

25.00%

$1.25

$1.32

$1.00

House Fan ( Low Speed )

0.50

100.00%

$2.00

$2.11

$1.00

Hair Dryer ( High Power) 

1.00

0.00%

$1.00

$1.05

$1.00

Hair Dryer ( Low Power )

0.91

9.89%

$1.10

$1.16

$1.00

Garbage Disposal Unit 

0.87

14.94%

$1.15

$1.21

$1.00

Drill        

0.96

4.17%

$1.04

$1.10

$1.00

Garage Door Opener

0.95

5.26%

$1.05

$1.11

$1.00

Heat Pump ( Low Power )

0.93

7.53%

$1.08

$1.13

$1.00

Heat Pump ( Medium Power )

0.78

28.21%

$1.28

$1.35

$1.00

Heat Pump ( High Power )

0.95

5.26%

$1.05

$1.11

$1.00

Water Pump     

0.78

28.21%

$1.28

$1.35

$1.00

Water Heater         

1.00

0.00%

$1.00

$1.05

$1.00

Air Conditioner 

0.97

3.09%

$1.03

$1.09

$1.00

Washing Machine  

0.54

85.19%

$1.85

$1.95

$1.00

Washing Machine ( Spin ) 

0.56

78.57%

$1.79

$1.88

$1.00

Dryer           

1.00

0.00%

$1.00

$1.05

$1.00

Refrigerator  

1.00

0.00%

$1.00

$1.05

$1.00

Oven         

1.00

0.00%

$1.00

$1.05

$1.00

Range       

1.00

0.00%

$1.00

$1.05

$1.00

Dish Washer   

0.97

3.09%

$1.03

$1.09

$1.00

Mixer (High Power)

0.99

1.01%

$1.01

$1.06

$1.00

Mixer ( Low Power)

0.60

66.67%

$1.67

$1.75

$1.00

Coffee Maker

1.00

0.00%

$1.00

$1.05

$1.00

Microwave 

0.97

3.09%

$1.03

$1.09

$1.00

Toaster   

1.00

0.00%

$1.00

$1.05

$1.00

Television Set

0.57

75.44%

$1.75

$1.85

$1.00

VCR      

0.85

17.65%

$1.18

$1.24

$1.00

Cassette Player

0.53

88.68%

$1.89

$1.99

$1.00

CD Player

0.78

28.21%

$1.28

$1.35

$1.00

Stereo 

0.76

31.58%

$1.32

$1.39

$1.00

Satellite Dish

0.53

88.68%

$1.89

$1.99

$1.00

Hard Disk Drive

0.59

69.49%

$1.69

$1.78

$1.00

Monitor    

0.61

63.93%

$1.64

$1.73

$1.00

Scanner   

0.62

61.29%

$1.61

$1.70

$1.00

Printer   

0.74

35.14%

$1.35

$1.42

$1.00

Photo Copier (at start)

1.00

0.00%

$1.00

$1.05

$1.00

Photo Copier ( at end)

0.79

26.58%

$1.27

$1.33

$1.00

FAX Machine    

0.62

61.29%

$1.61

$1.70

$1.00

Answering Machine

0.71

40.85%

$1.41

$1.48

$1.00

Uninterruptible Power Supply  

0.80

25.00%

$1.25

$1.32

$1.00