AC Power Factor, IEC Testing And NRTE Food Safety Presentation-105.pdf · (‘ANSI’) in concert with NEMA and EEI AC Power Factor, IEC Testing and NRTE Food Safety The standards

AC Power Factor, IEC TestingAnd NRTE Food Safety

June 26, 2013International Microwave Power InstituteAnnual Symposium Providence RI USA

Steven J. DruckerChief Technology Officer

Microwave Science JV LLCNorcross GA USA

[email protected]

© Microwave Science JV LLC 2013

• Hypothesis:The AC electrical environment impacts IEC measured

microwave oven wattage in a consistent, statistically

significant manner.

• The AC Electrical Environment

• Lab Work. IEC 60705 Tests and AC Power Factor

• Statistical Testing of Data

• Conclusions

AC Power Factor, IEC Testing and NRTE Food Safety

• Hypothesis


• AC Power Factor

• Voltage



• Conclusions


In an ideal DC current world, all power is ‘Real’Voltage * Current = Power

AC Power Factor, a fact of life well known as early as 1895,

Impacts the performance of all inductive loads.


Voltage * Current * Power Factor = Power

Inductive loads return a portion of the energy used back to the power company.

Refrigerators, Freezers, Air conditioners (all types) , Fluorescent lights including CF lights, TV,

computer, stereo, any wall-wart , Microwave Oven, Washer, Dryer, Vacuum cleaner, Fans, Power tools: grinder, electric saw, compressor, Humidifier, dehumidifier, Garage door opener, pool pump, electric lawn mower, etc


AC power factor is not only a function of

The ‘point load’ (i.e. your microwave oven), but EVERY inductive load

between you and the upstream transformer out on the pole or in the utility

room of your building.

Conceptual vs Schematic Magnetron Renderings

Microwave ovens themselves are an inductive load.


AC Power Factor: AC is not DC

What The Power Company Supplies aka ‘Apparent Power’ or

Voltage * Current


AC Power Factor: AC is not DC

What you get toDrink aka ‘Real Power’ or

Voltage * Current * Power Factor


Measurement of Real Power In AC CircuitsRequires The Simultaneous Measurement of

Voltage and Current


http://www.powerqualityworld.com/2011/04/ansi-c84-1-voltage-ratings-

Mains voltage varies within bounds set forth by the American National Standards Institute

(‘ANSI’) in concert with NEMA and EEI


The standards have worked for 125 years, and so does your Microwave.

Right—so what’s the issue?


127V 120V 113V 106V

MWO 1 930 877 795 671MWO 2 951 871 755 673MWO 3 948 897 776 636MWO 4 937 871 740 644MWO 5 922 876 720 587

Avg. 937 878 757 642Avg.

Power Change

From 120V

7% 0% -14% -27%

Notes:

1. At 120V, tested wattage is less than labeled wattage.

2. The non-linear relationship between wattage and mains voltage


• Hypothesis



• Test Beds and Methodology

• Test Results


• Conclusions


RMS Multi-Meter

Watt Meter

Splitter

Neglect Power Factor.Digital Wattmeter reads out in Watts.

(Multimeter reads RMS voltage from Splitter—As per the IEC 60705 microwave oven test protocol)


Watt Meter

Variable AC Transformer

Consider Power Factor.Digital Wattmeter Reads out in Watts—

Measures Voltage and Current Simultaneously


Microwave Descriptions

1 GE 1100 Watt 1.2Cuft

2 LG 1200 Watt 1.2Cuft

3 Frigidaire 1100 Watt 1.2Cuft

4 Kenmore 1100 Watt 1.2Cuft

5 Emerson 1100 Watt 1.2Cuft


Accurate, repeatable and expressive of microwave oven cooking efficiency

(Portions used by permission. © 2012 Robert F. Schiffmann. All rights reserved)


IEC 705 (mod) Wattage

OVEN IDConsider Power

FactorNeglect Power Factor

(IEC Method)1 895 9261 878 8931 879 9032 924 9562 926 9472 941 9323 894 9273 886 9083 887 9024 941 9794 940 9694 935 9565 863 9015 855 8885 849 870





FactorNeglect Power Factor

(IEC Method)%

Delta1 895 926 3%1 878 893 2%1 879 903 3%2 924 956 3%2 926 947 2%2 941 932 -1%3 894 927 4%3 886 908 3%3 887 902 2%4 941 979 4%4 940 969 3%4 935 956 2%5 863 901 4%5 855 888 4%5 849 870 2%

• Hypothesis




• Conclusions


Statistical Analysis

Statistical validation is mandatory for our work



IEC 705 (Mod.) Watts

OVEN ID

Consider Power Factor

Neglect Power Factor (IEC

Hookup)1 895 9261 878 8931 879 9032 924 9562 926 9472 941 9323 894 9273 886 9083 887 9024 941 9794 940 9694 935 9565 863 9015 855 8885 849 870

ANOVA

Source of Variation SS df MS FP-Value F crit

Sample 26739.3 4 6684.82455.42449 0.0002.866081

Columns 4451.372 1 4451.37236.90673 0.0004.351244

Interaction 243.9584 4 60.98959 0.50567 0.7322.866081

Within 2412.227 20 120.6114

Total 33846.85 29

Let’s Evaluate Power Factor First

Good news: ANOVA reports that the columns

are different in a statistically meaningful manner

down to an alpha of 0.001




Factor


Method)%

Delta1 895 926 3%1 878 893 2%1 879 903 3%2 924 956 3%2 926 947 2%2 941 932 -1%3 894 927 4%3 886 908 3%3 887 902 2%4 941 979 4%4 940 969 3%4 935 956 2%5 863 901 4%5 855 888 4%5 849 870 2%

In the context of ANOVA, ‘Interaction’ compares columns on a row by row

basis, evaluating whether they are alike or different in a statistically

meaningful manner


IEC 705 (Mod.) Watts

OVEN ID

Consider Power Factor


Hookup)1 895 9261 878 8931 879 9032 924 9562 926 9472 941 9323 894 9273 886 9083 887 9024 941 9794 940 9694 935 9565 863 9015 855 8885 849 870

ANOVA

Source of Variation SS df MS FP-Value F crit

Sample 26739.3 4 6684.82455.42449 0.0002.866081

Columns 4451.372 1 4451.37236.90673 0.0004.351244

Interaction 243.9584 4 60.98959 0.50567 0.7322.866081

Within 2412.227 20 120.6114

Total 33846.85 29

Good news: ANOVA ‘Interaction’ analysis

reports that the rows are similar with respect to

a column by column comparison, i.e. well

behaved oven population and very consistent test

technique

127V 120V 113V 106V

MWO 1 930 877 795 671MWO 2 951 871 755 673MWO 3 948 897 776 636MWO 4 937 871 740 644MWO 5 922 876 720 587


ANOVASource of Variation SS df MS F P-ValueF crit

Rows4709.43

9 4 1177.363.03268

6 0.0613.25916

7

Columns 258400 386133.3

4221.865

4 0.0003.49029

5

Error4658.68

1 12388.223

4

Total267768.

1 19The five ovens are statistically similar one to another within each voltage

tested, BUT the five ovens exhibit statistically meaningful differences in

IEC output wattages across the ANSI C84.1 specified range of allowable

voltages

Next Let’s Evaluate

Voltage

• Hypothesis




• Conclusions



Statistical validity of AC Power Factor and Mains Voltage effects leads us

Down the rabbit hole re NRTE Microwave Food Validations

GMA 2008 NRTE Validation Guidelines omit consideration of the influence of the AC Electrical Environment


We have eaten of the apple, Now we have to choose: Is our world AC or DC?


Should we continue to rely solely on GMA NRTE Validation

Guidelines (2008) for ‘dumb’ ovens and co-dependently

neglect the influence of power factor and mains voltage, OR…


The influence of the AC electrical environment is statistically confirmed

Should we put in place

NRTE Foods’ Validation

protocol for the new generation of

‘Smart Ovens’ (more than 2 million now in use)?


Thermocouple # Degrees Farenheit

1 2 3 4 5 6 7 8 9 10

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

Date Weight TCP+ Code MWO#Lot #

Test # Time Stamp WeightCod

eMWO

# Lot #Mean Temp

Max Temp

Min Temp 1 2 3 4 5 6 7 8 9 10

123456789

1011

Draft Protocol To Validate NRTE Microwave Food Preps In A Smart Oven

AC environment management, cold / warm oven management, a single

compiled input code operative across a range of SMART (independently

peer reviewed) ovens, NIST calibrated thermocouples, test samples across

the target weight range, 100% kill temperatures as per the National Advisory

Committee on Microbiological Criteria for Foods (NACMCF)


AC Power Factor, IEC TestingAnd NRTE Food Safety

June 26, 2013International Microwave Power InstituteAnnual Symposium Providence RI USA

Steven J. DruckerChief Technology Officer

Microwave Science JV LLCNorcross GA USA

[email protected]

© Microwave Science JV LLC 2013

Documents

AC Power Factor, IEC Testing And NRTE Food Safety Presentation-105.pdf · (‘ANSI’) in concert with NEMA and EEI AC Power Factor, IEC Testing and NRTE Food Safety The standards