FACT:FACT:FACT:FACT:Grounding is the most Grounding is the most

misunderstood aspect of misunderstood aspect of Electrical DistributionElectrical DistributionElectrical DistributionElectrical Distribution

Current Flow to Physical Earth Current Flow to Physical Earth i T i l VFD C ll iin a Typical VFD Cell using conventional grounding

• POWER SUPPLY• DRIVE  *typically utilizes IGBT technology• MOTOR• WIRING SYSTEM ( MOST NEGLECTED COMPONENT)

Transformer Case Frame Motor FrameDrive Frame ( V F D ) *

Conventional input cabling Conventional output cabling

• WIRING SYSTEM ( MOST NEGLECTED COMPONENT)

PEPE PEPE

StatorWindingsIN

PUT

OUTP

UTI f-g = high

PE PE

Oscilloscope reads approximately 1 500 illi i t d

gfrequency ground currents

I f-g I f-gI f-g

1,500 milliamps going to ground PE NEC.Sect.250 PCC

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Fast switching power devices utilizing               IGBT technology produce electrical interference

(High Frequency Ground Currents,                   )Bearing Currents, Shaft Currents, ) which

Can BeC B Can BeCannot Be

R di t d

ContainedEliminated

ONLY By using Zero Ground HFES

RedirectedControlled

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Issues resulting from High Frequency            Ground Current flow in a typical VFD cell

…Will enter ground grid and travel in all…Will enter ground grid and travel in all directions, with arcing, sparking and shocking as potential safety concerns

d h h h h…Can discharge through the motor, causing   premature motor bearing failure, which 

causes premature motor failure. 

…Can re‐enter ground paths through the ground and  disrupt sensitive electronic equipment and adjacent drive systemsequipment and adjacent drive systems

…This HF ground current flow is the basis for recommended output cable distance limitation 

f 50 f b ASD fwww.zero-ground.com 866-ZERO-GND ©2008-2011 ZERO GROUND page 4

of 50 feet by most ASD manufacturers

High Frequency Ground Current Path - Motors

R d C iti li b t t t d tRed – Capacitive coupling between stator and rotorGreen – Inductive coupling through bearings to earth

Colored lines show the various paths High Frequency Ground Currents take through the motor (bearings, shaft, etc) 

when a VFD and motor are grounded conventionally to Physical Earth (PE)

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HFES Creates the f d d hPreferred Grounding Path

Unlike other VFD Cable Systems (used only on output side), only Zero Ground HFES is designed and

rated to be used on the input and output side of the Drive. Also unlike traditional VFD cabling, HFES is

a completely passive system, and can be used wherever greater than 50 ft. lengths are required.

Our HFES Flexible Cable Assembly takes conventional Drive System wiring materials and combines

them in a unique and patented design to create a continuous preferred grounding path. That is how

Inner Component Outer Component

them in a unique and patented design to create a continuous preferred grounding path. That is how

HFES Contains, Controls and Redirects High Frequency Ground Currents and other nuisance noise

AWAY from physical earth (ground). Industry standard fittingInner Component Outer Component fitting

Patents have been issued for ZERO GROUND HFES

C t d I t ll ti

NOTE: Inner Component is inserted into Outer Component when shipped

UL listed components and cable assemblyComponents and Installation

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p yMSHA approved cable assembly

ZERO GROUNDZERO GROUND HFESHFESZERO GROUND ZERO GROUND HFESHFESApplication SummaryApplication Summary

Low A system of passive wiring components 

engineered to a specific drive cell

500 HP

Voltage (1000V)

engineered to a specific drive cell

Patented flexible cable assembly and patented installation method, for retrofit or new drive cells

INPUT and OUTPUT wiring 

500 HP or less

retrofit or new drive cells

Fully compliant with NEC 250 and CSA Section 10

gsystem Not designed to resolve all issues 

associated with drives and motors

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HFES delivers continuous ROI –Why ZERO GROUND HFES is your best

M bl hi h f d t l t i D i

Why ZERO GROUND HFES is your best long‐term solution

Measurable high frequency ground currents are always present in a Drive System, with the potential to create safety issues, induce premature motor bearing failure and disrupt sensitive devices and systems on the same or adjacent grounding gridsthe same or adjacent grounding grids.

‐‐‐Enables upfront planning for prevention instead of funding ongoing maintenance and unplanned downtime recovery

No regular maintenance required‐‐‐No regular maintenance required ‐‐‐No active components to complicate your system‐‐‐No frequency dependent components (like filters)‐‐‐No routinely replaceable components (like brushes)‐‐‐No distance limitations with HFES (cable assembly runs can be moved 

or extended as needed)

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