Imagination at work Ground Fault Circuit Interrupters Jonathan Potter GE Energy Management Industrial Solutions

Imagination at work

Ground Fault Circuit InterruptersJonathan PotterGE Energy ManagementIndustrial Solutions

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Purpose of GFCI’s

GFCI devices protect people from hazardous electric shock

Listed to UL 943Breakers also comply with UL 489

GE Industrial Solutions | November 2014

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1970

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GF

CI's

(m

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0

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Ele

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# of GFCI's # Electrocutions

Electrocutions Associated With Consumer Products (US Data)


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Basic Concepts Ground Fault / Residual Current

Electric current that flows from electrical equipment through a human to ground.

Terms used: UL 943: ground fault current

IEC: residual current

Potential causes:

• Insulation fault in the equipment.

• Wiring fault in the equipment or installation.

• Current from equipment to earth in absence of fault.


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GFCI/RCD Technology

VOLTAGE DEPENDENT (VD)• Device with electronic detection, evaluation and/or

interruption functions, that is dependent on line supply voltage

• Differential current detection typically by current transformer

• Current interruption by electromagnetic mechanism with electrical contacts.

VOLTAGE INDEPENDENT (VI)• Electromechanical device in which neither detection,

evaluation nor interruption depend on line supply voltage

• Differential current detection and energy for operation typically by current transformer GE Industrial Solutions | November 2014

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Benefits of Voltage Dependent technology

Electronics provide features not generally available to Voltage Independent devices :

Higher detection sensitivity

– VD devices: max 6 mA - threshold for “let-go” current (UL 943)

– VI devices:

min 20 mA - threshold current for ventricular fibrillation, require special manufacturing techniques


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End of life indication• UL 943 specifies that GFCIs at end of life shall, upon

conducting an internal test, either:

– a) provide an indication that the device needs replacing, or

– b) make the device unable to deliver power.


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1 mA

Current Level(Milliamperes)

5 mA

6-16 mA

17-99 mA

100-2000 mA

> 2000 mA

Perception level. Slight tingling sensation.

Slight shock felt; not painful but disturbing. Average individual can let go. However, strong involuntary reactions to shocks in this range may lead to injuries.

Painful shock, begin to lose muscular control. Commonly referred to as the freezing current or "let-go" range.

Extreme pain, respiratory arrest, severe muscular contractions. Individual cannot let go. Death is possible.

Ventricular fibrillation (uneven, uncoordinated pumping of the heart.) Muscular contraction and nerve damage begins to occur. Death is likely.

Cardiac arrest, internal organ damage, and severe burns. Death is probable.

Probable Effect on Humans



VDVI

>20mA

gap

References• NIOSH [1998]. Worker Deaths by Electrocution; A Summary of NIOSH Surveillance and Investigative Findings. Ohio: US Heath and Human Services.• Greenwald EK [1991]. Electrical Hazards and Accidents - Their Cause and Prevention. New York: Van Nostrand Reinhold.

Load

IIn

IOut

If the current out = current back, the differential current transformer shows no output.

L

N

Differential Current Transformer

Current “Adding Machine”

How GFCI’s work


How GFCI’s work

Current “Adding Machine”

240VLoad

IIN

IOut

L1

L2

N120/240V

Load

IIN

IOut

L1

L2




Current “Adding Machine”Under Ground Fault Conditions

Load

IIn = 6A

IOut = 5.9A

Ground-Fault

.1A

L

N


If I-out does not equal I-in, the differential current transformer creates an output signal.

How GFCI’s work


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GFCI location requirements per US National Electric Code 2014

In general, GFCI devices are required in wet locations

Bathrooms, Garages, Outdoors, Unfinished basements

Kitchens near countertops

Sinks – Where receptacles are installed close to the sink

Bathtubs or shower stalls - where receptacles are installed close to the shower stall or tub

Laundry areas

Boathouses

Dishwashers

And other locations…


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Questions???


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Imagination at work Ground Fault Circuit Interrupters Jonathan Potter GE Energy Management Industrial Solutions