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IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 15, NO. 3, JULY 2000 1045

Filtering Dispersed Harmonic Sources on DistributionWard Jewell, Senior Member, IEEE, William (Bill) L. Miller, and Tom Casey

AbstractTelephone company customers reported audible

noise in their telephone service. Through measurements, analysis,and simulations, 540 Hz noise was found to be coupling frompower distribution to telephone cables in a shared undergroundright-of-way. The source of the noise was small single-phaseelectronic loads dispersed throughout the power distributionsystem in the area. A passive shunt filter was designed using anexisting capacitor bank. Installation of this filter reduced the noiseto acceptable levels.

Index TermsEarth, grounding, harmonic analysis, passivefilters, power distribution electromagnetic interference, powerfilters, power system harmonics, power system modeling, powersystem simulation, wire communication interference.

I. INTRODUCTION

TELEPHONE customers in a suburban area complained to

the telephone company of noisy telephone service. In one

case the noise interfered with the operation of a PBX system.

Telephone company personnel investigated and found evidence

of noise contribution from the electric power system serving

the area. Electric utility and telephone company engineers then

began working together to find a mutually acceptable solution.

II. TELEPHONE NOISE

Telephone company personnel initially received a call from a

hospital complaining of getting wrong numbers when calls were

placed through their PBX. An excessive common mode voltage,

93 dBrnC at 540 Hz, the ninth harmonic of 60 Hz, was found onthe telephone trunk lines of the analog telephone system serving

the hospital.

For an immediate solution to the hospitals problem noise

chokes were installed on the affected trunks. These reduced the

trunk lines susceptibility to common mode voltage and solved

the hospitals outbound calling problems.

The telephone company then performed a shield investigation

and found an open shield on one telephone cable. The shield

was repaired, reducing the 540 Hz common mode voltage to

84 dBrnC. This is acceptable.

Within a few months, however, calls were again received

from the hospital and from other customers in the area com-

plaining of audible noise when using their telephones. The

540 Hz common mode voltage was measured on the trunk lines

and was again above 90 dBrnC. An inductive survey showed

the telephone systems shielding to be in good condition. The

Manuscript received March 16, 1998; revised November 15, 1999.W. Jewell is with the Power Quality Laboratory, Wichita State University,

Wichita, KS 67260 USA.W. L. Miller is with Southwestern Bell Telephone, Topeka, KS 66603 USA.T. Casey is with Kansas City Power and Light, Kansas City, MO 64141 USA.Publisher Item Identifier S 0885-8977(00)08134-6.

Fig. 1. Power and telephone circuits.

survey found high 540 Hz influence from the power system

along one exposure.

It is common for 540 Hz to be the dominant frequency in in-

terference between telephone and electric power systems, even

though third harmonic, 180 Hz, current has a higher magni-

tude in the power system. The design of the telephone system

makes it more susceptible to inductively-coupled interference at

540 Hz than at 180 Hz. Telephone equipment is has a highpass

filter on the input to reduce its exposure to 60 Hz and low order

harmonics. Loaded telephone cable also has a lowpass filter ef-

fect that reduces these frequencies. The human ear is also non-

linear and is more sensitive to 540 Hz than 180 Hz audible noise.

This is reflected in the C-Message curve [1], which is a productof several elements in the telephone network and the function

of the human ear.

The exposure is shown in Fig. 1. Two 7200/12 470 V

three-phase distribution circuits begin at the utility substation.

For 1.5 miles these circuits share a common underground

right-of-way with telephone cables. Circuit 1 serves residential

loads and the hospital; circuit 2 serves residential loads.

An insulated probe wire 100 feet in length was run along

the ground parallel to and above the underground right-of-way.

The wire was electrically connected at each end to a conducting

metal stake driven into the earth. The current flowing on this

probe wire indicated an earth current of 41 A, with an excessive

contribution at 540 Hz. The spectrum of this current is shown inFig. 2.

The probe wire and stakes were then moved perpendicular

to their original path and to the path of the right-of-way. The

same earth current, 41 A, was measured. This indicated that the

current measured was earth current, which will flow on a probe

wire running any direction. Current in thepowerconductors will

only induce probe wire current when the probe wire is parallel

to the conductors.

Earth current is power system neutral current. In a multi-

grounded neutral distribution system, it is commonfor only 40%

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1046 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 15, NO. 3, JULY 2000

Fig. 2. Earth current spectrum.

of the neutral current to return through the system neutral con-

ductors. The other 60% returns through the earth; these are com-

monly accepted numbers in the telephone industry.

All currents in the power distribution phases, neutral, and

other return paths, contribute to the magnitude of the magnetic

fieldalong thepath of a distribution system. If phase currents are

balanced, the geometry of the phase conductors cancels most of

this magnetic field. If phase currents are unbalanced but all re-

turn current were to flow on the system neutral, geometry could

still cancel the field. However, because much of the return cur-

rent does not flow on the neutral, geometric cancellation is de-

creased and the magnetic field becomes stronger. This magnetic

field links with telephone cables and induces common mode

voltage, or power influence, on them. When power influence

becomes too large, the audible noise on telephone circuits be-

comes unacceptable. In addition, earth current may flow on thegrounded telephone shield, further increasing the noise coupling

with the telephone conductors.

Telephone cable shielding reduces the effect of magnetically-

induced current by conducting a similar current on the shield in

the opposite direction. This shield current reduces the common

mode voltage on the cable. In this case, however, the net 540 Hz

disturbing currentthe current contributing to the distribution

system 540 Hz magnetic fieldwas too great for its effects to

be cancelled by shielding.

Another way to eliminate the interference problem would be

to convert the analog telephone system in the area to a fiber

optic system. This is very expensive, however, and the telephone

company wanted to investigate less expensive options beforetaking this step. The electric utility was contacted for assistance

with the problem.

III. FIELD ANALYSIS

The troubleshooting and mitigation process now turned to lo-

cating the source of the harmonic currents and the path through

which they were entering the earth.

A. Capacitors

Telephone company personnel used a van-mounted loop an-

tenna feeding a spectrum analyzer to search for power factor

TABLE ICIRCUIT 1 FIELD MEASUREMENTS

correction capacitors that might be in series resonance with dis-

tribution line reactance. Series resonant capacitors provide a

low-impedance path to neutral and earth for harmonic currents

at the resonant frequency. Most harmonic current at that fre-

quency on the distribution conductors will return to the neu-

tral/earth return through the resonant capacitor bank. This pro-

duces high harmonic currents in the earth at that point, which

can increase telephone noise.If capacitors are in resonance, harmonic suppression reac-

tors can be installed in the neutrals to change the resonant fre-

quency to one that will not produce high capacitor currents.

Alternately, the capacitor connection to neutral and earth can

simply be opened, breaking the path for harmonic currents to

flow to earth.

The harmonic levels in the distribution conductors are signif-

icantly different on either side of the resonant bank, because

the bank shunts most of the resonant harmonic current from

the lines to neutral and earth. The radiated harmonic energy de-

tected by the loop antenna therefore changes when the antenna

passes a bank in resonance. The loop antenna survey of this dis-

tribution system found no such resonances.

Resonances can also be found by switching capacitor banks

off one at a time while watching the harmonic currents on the

distribution lines. When a bank in resonance is switched off,

harmonic currents will decrease significantly. On these two cir-

cuits, harmonic currents on phase conductors were monitored at

the substation, and telephone noise was monitored at an affected

customer, while capacitors on the system were switched off.

The most significant effects were found when capacitors on

circuit 1 were removed. On this circuit harmonic currents on

the phase conductors and audible telephone noise changed each

time a bank was removed. The recorded values are presented in

Table I. By the time all banks were removed from the two cir-cuits, the telephone noise level was at an acceptable level. These

changes indicate the harmonic currents were traveling to earth

through the capacitors. Capacitors, whether in resonance or not,

provide a lower impedance path to neutral and earth than loads

or transformers because their impedance decreases as frequency

increases. However, no single significant change was measured,

and no significant decrease was measured until all capacitors

were switched off, indicating that no banks were in resonance.

Observation over an extended period indicated that the tele-

phone noise was worse during spring and fall, the utilitys light

load times. This is common in situations where harmonic cur-

rents are conducted to earth through capacitors. Increased load

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JEWELL et al.: FILTERING DISPERSED HARMONIC SOURCES 1047

TABLE IITRANSFORMER SATURATION TEST

means decreased resistance in parallel with the capacitor banks.

The lower resistance tends to dampen the tuned circuit of capac-

itor banks and systemreactance. Damping reduces the harmonic

levels.

Y-connected three-phase capacitor banks conduct only

unbalanced currents and zero-sequence currents to neutral and

earth. Balanced positive and negative sequence currents sum to

zero at the Y neutral point. Open fuses in one or two phases

of a three-phase capacitor bank cause severe imbalances in the

currents, and greatly increase the current conducted to earth. Autility line crew checked all capacitors on the circuits for open

fuses; none were found.

B. Harmonic Sources

Customers on the distribution system were evaluated for har-

monic sources. The two circuits involved in this study served

residential loads and the hospital. While hospitals can be signif-

icant harmonic sources [2], this hospital was not drawing sig-

nificant harmonic currents. Its location between the substation

and the exposure between power and phone lines also made it

unlikely to be the cause of noise problems.

Harmonic currents were measured at various places on the

distribution circuits. Harmonic current levels of around 5%

THD were found on the phase conductors at the substation,

with the 540 Hz contribution being less than 0.5%. These are

acceptable levels that usually cause no harmonic problems [3].

No significant sources of harmonic currents were found.

One possible source of harmonics on a distribution system is

saturated transformers. Saturated transformers draw high levels

of exciting current, which is distorted with odd harmonics. Re-

ducing the voltage magnitude will decrease transformer satura-

tion currents.

The tap-changing transformer at the substation was stepped

down from its normal voltage levels. The voltage levels and re-sulting telephone interference levels are shown in Table II. No

significant change was measured, indicating no transformers in

saturation.

C. System Neutral

If the system neutral conductor is open, then the approxi-

mately 40% of the return current it normally carries will flow

through the earth. This significantly increases earth currents and

the resulting telephone noise. Line crews therefore inspected

the underground system neutrals and found them to be in good

condition.

D. Conclusions of Field Analysis

No significant sources of harmonic current were found on the

circuits involved. Harmonic levels were not unusually high on

any of the phase conductors anywhere in the system. The dis-

tribution system was in good condition with no open capacitor

fuses or capacitors in resonance. The conclusion was, then, that

the source of harmonics was the many small single-phase elec-

tronic loads dispersed throughout customers homes in the af-

fected area. This conclusion was tested by developing a model

of the system and simulating the system operation.

IV. MODELING AND SIMULATION

The distribution system of circuit 1, including neutral con-

ductors and earth return, was simulated using techniques similar

to the practices outlined by the IEEE Task Force on Harmonics

Modeling and Simulation [4], [5]. The flow of ninth harmonic

current in the earth was of primary interest in this analysis, so

load flow constraints were not needed. Because of this, time-do-

main analysis was acceptable [4] and the Electromagnetic Tran-sients Program (EMTP) [6], [7] was used.

EMTP software creates and solves the time-based differential

equations describing the circuit being simulated. Outputs are

time-varying voltage, current, and power at any selected points

in the system. Any of these may then be analyzed for harmonic

content using a Fourier transfer algorithm.

A. System Model

The circuit models used in the simulation are shown in

Figs. 35. Three-phase models were used because zero-se-

quence (neutral/earth return) currents were to be calculated;

Figs. 3 and 4 show only one of the three phases. Fig. 3

shows the models for phase conductors, Y-connected power

factor correction capacitors, and connections to neutral and

earth. Fig. 4 shows the model representing lumped linear and

harmonic loads, while Fig. 5 shows the model of the system

neutral.

The utility provided values of phase conductor impedances

used in power flow and short circuit studies. These impedances

were used in this model. They are the reactance and resistances

shown in Fig. 3 between main nodes, such as Substation to 1,

or 3 to 4. Because the model only needed to be accurate at rela-

tively low frequencies, up to about 3000 Hz, the 50th harmonic

of 60 Hz, and because the lines being modeled were very short,

less than 5 miles in length a frequency-dependent model withdistributed parameters was not needed [4].

Power factor correction capacitors are shown in Fig. 3 from

the numbered node to the neutral N nodes, such as 1 to 1N, 2

to 2N, etc. Loads are modeled as lumped equivalents in parallel

with the capacitors.

The load model, shown in Fig. 4, combines a linear resistive

load with a nonlinear single-phase rectifier load. This model

represents the collective effects of a large number of single-

phase rectifiers dispersed throughout the portion of the distri-

bution system between the node to which it is connected and

the next node on the system [8]. It can accurately simulate any

combination of linear load and single-phase rectifier load. The
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Fig. 3. Distribution system circuit model.

Fig. 4. Lumped load model.

Fig. 5. System neutral model.

values of linear load resistance, dc load resistance, and rectifier

filter capacitance are calculated from measured current values,

Fig. 6. Capacitors on circuit 1.

including harmonic currents, and from utility load estimates. No

reactance was included in the linear load because it would have

little effect on the relevant simulation results for this system. It

could be included if needed, however.In Fig. 3 the resistance from the neutral N to the system

neutral SN node, for example, 1N to 1SN, represents current

flowing onto the system neutral from the loads and capacitors

at the node. The resistance from the N node to ground repre-

sents current flowing through earth and other return paths. The

current is assumed to split evenly between system neutral and

other paths in this case, so the two resistances are equal.

The system neutral is then modeled as shown in Fig. 5. This

circuit allows the neutral current to be monitored as a simulation

output. Because neutral and other return currents are assumed to

be equal, the neutral current output can also be considered to be

the earth and other return current output.

This is an extremely simplified model of earth current thatassumes the earth current flows in a straight path parallel to the

system neutral conductors. In reality, earth current spreads out

over a wide geographic area as it flows. It will follow theshortest

path, the path of least resistance, to return to its source. Anal-

ysis of earth current usually requires the use of Carsons equa-

tions [9]. However, in this simulation we are concerned with the

earth current that is coupling with the telephone cables in the

same right-of-way as the system neutral and phase conductors.

For this reason, and because the lines are short, and because

only relative values, i.e., increases or reductions in earth current

magnitudes, were needed from the simulation, it was felt that

this simple model would be adequate.

B. Simulation Results

Initial simulations were run to compare the models results

with actual conditions. In each case, simulation results were

compared with measured values of currents and voltages on the

phase conductors under similar conditions.

The first case simulated was with all capacitors energized and

daytime light-load conditions, with normal levels of rectifier

load dispersed throughout the circuit. Following this, capacitors

were removed one at a time, beginning with node 1, and moving

outthrough nodes 24, until allcapacitors were off. Fig. 6 shows

the location of capacitors on circuit 1.
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TABLE IIISIMULATION BASE CASE RESULTS

TABLE IVSIMULATION RESULTS: OPEN CAPACITOR NEUTRAL

The simulated earth return current and the 540 Hz component

were recorded for each case. The 540 Hz component with all

capacitors energized was equated to the high noise levels mea-

sured at the affectedcustomer forthe same conditions. Thenoise

calculated for the case with all capacitors off was equated to the

acceptable noise levels measured during that condition. These

values were then used in subsequent simulations to judge the

telephone noise levels. Relative noise values, both simulated and

measured, for these firstfive cases arepresented in Table III. The

noise value for the base case, all capacitors energized, is used asthe per unit base, so that noise is presented as 1.0.

While the increased earth current as banks 13 are removed

does not agree with the measured values, the simulation results

do indicate, in agreement with field measurements, that when

all capacitors are off, 540 Hz noise drops significantly.

These simulation results supported the conclusion that the

telephone noise was caused by small, dispersed single-phase

electronic loads throughout the distribution system, especially

on circuit 1.

In the next series of simulations the capacitors were ener-

gized, but the neutral point on each bank was disconnected from

the system neutral and earth. This was accomplished in the sim-

ulation by removing the connection from the lower end of thecapacitor to the neutral node, (1N4N on Fig. 3) leaving the

three-phase Y-connected bank energized but isolated from the

system neutral and ground. This blocks the flow of harmonic

current through the capacitor bank into earth. The results of

these simulations are presented in Table IV.

Table IV shows that as successive capacitor neutrals are re-

moved, beginning near the substation and moving out on the

feeder, the harmonic currents in the earth and other return paths

increase until allcapacitor banks are removed. When a capacitor

bank is grounded, harmonic currents from loads near that bank

see the bank as the low impedance path back to their source.

When the capacitor ground is opened, the currents then see

TABLE VSIMULATION RESULTS: HARMONIC SUPPRESSION REACTORS

the next bank out on the feeder as the lowest impedance path,

causing them to flow through the neutral, earth, and other re-

turn paths to the next bank and across a greater length of the

telephone exposure. This continues until all banks are removed

from the feeder, when the harmonic currents no longer see any

low impedance capacitor paths back to neutral and earth, and the

system returns to close to the original condition of all capacitors

being grounded.

These results indicate that removing the ground connections

from the capacitor banks will not accomplish the desired tele-

phone noise reduction. By the time this result was available the

utility had already considered this solution and rejected it. A

safety problem for line crews occurs when capacitor grounds

are opened. The capacitor neutral point, which has always be-

fore been at earth potential, can no longer be assumed to be at

that low voltage. It must now be assumed to be at any voltage up

to full line voltage, and line crews must be retrained to assumethis.

The next set of simulations installed a harmonic suppression

reactor (HSR) in the neutral of each capacitor bank. While there

was no resonant capacitor, the common use of HSRs, it was

thought that the additional reactance might decrease the har-

monic earth current to acceptable levels. Table V shows the re-sulting noise levels, which were still unacceptably high.

The next step, then, was to consider installing a shunt filter to

reduce the harmonic currents in the earth exposure between the

distribution lines and telephone cables.

V. FILTER DESIGN

A shunt harmonic filter provides a low impedance path to

neutral for currents at the tuned frequency. This is accomplished

by placing an appropriate reactance in series with existing ca-

pacitors. Because this retunes thewhole distribution system, it is

necessary to simulate the filter under varying conditions during

the design process.

Fig. 7 shows two designs for a shunt filter on a three-phase

bank. Design (b) is recommended, with one reactor per phase.

But the telephone company and electric utility already had expe-

rience with harmonic suppression reactors, which are installed

as shown in design (a), so this design was used.

To tune the filter in design (a) for low impedance at frequency

, the inductance is

(1)

Two different 7200 V capacitor sizes were installed on this

circuit; 1200 kVAR (20.5 F), and 600 kVAR (10.2 F). The

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Fig. 7. Shunt filter designs.

TABLE VISIMULATION RESULTS: 540 Hz SHUNT FILTER

inductance required to tune the 1200 kVAR capacitor to 540 Hz

is 1.4 mH. The 600 kVAR requires 2.8 mH.

Three cases were simulated:

1) Filters at all four capacitor banks.

2) Filter at bank 2 only.

3) Filter at bank 3 only.

The results are shown in Table VI.

Applying filters at all four banks reduces the harmonic noise

to an acceptable level. Filtering at only bank 2 or 3 produces

even lower noise than filters at all four. A filter at bank 2 or 3

removes from the exposure much of the 540 Hz current gen-

erated between banks 2 and 4, while not drawing a significant

harmonic current from the other end of the exposure. On thiscircuit it was physically impractical to install a filter reactor on

the pole at bank 2, so the filter at bank 3 was chosen for further

study.

All combinations of capacitors on and off the system were

then simulated with the shunt filter installed at bank 3. Higher

load levels were also simulated. The noise levels remained at

acceptable levels for all conditions.

The simulated values of currents through the capacitor bank

were analyzed to insure the bank would not be overloaded by the

increased 540 Hz current it was carrying. The current through

the filter reactor was used to specify the current capacity of the

reactor itself.

VI. FILTER TEST AND INSTALLATION

The shunt filter was tested at bank 3. A harmonic suppression

reactor of the correct inductance was temporarily installed in

the capacitor neutral. Telephone noise levels were monitored at

the affected customers. Capacitor and filter reactor current and

voltage were also recorded.

VII. FILTER RESULTS

Before the reactor was switched in, the 540 Hz noise at the

affected telephone customers was 95 dBrnC. When the reactor

was switched in, the noise level dropped to 87 dBrnC, an ac-

ceptable level. Capacitor and reactor voltages and currents were

within their ratings and design ranges.

The steady-state current ratings of the harmonic suppression

reactor used in the test were too low to permanently install it as

a filter reactor; it is intended to block currents, so its ampacity

is relatively low. An oil filled reactor was ordered from a trans-

former manufacturer and was permanently installed at bank 3.

The permanent reactor produced the same noise reduction as the

test reactor. Noise levels on the telephone circuit have stayed

within acceptable ranges ever since.

VIII. CONCLUSIONS

Small, dispersed single-phase electronic loads on a residen-

tial/commercial feeder caused harmonic distortion significant

enough to cause unacceptable telephonenoise. An analysis tech-

nique involving field measurements and simplified modeling

of the distribution system was used to successfully analyze the

problem and design and implement a solution. The technique

involves a very simple model of earth and other return paths,

which assumes the return current splits equally between the

system neutral and the earth and other return paths, and follows

the geographical path of the phase conductors.

An existing three-phase power factor correction capacitor

bank was converted to a shunt harmonic filter to divert har-

monic currents from the exposure between electric power and

telephone cables. This reduced noise to an acceptable level.

REFERENCES

[1] IEEE Recommended Practice for Inductive Coordination of Electric

Supply and Communication Lines, IEEE Std. 776-1992, 1992.[2] W. Jewell, The effects of voltage sags in hospitals, in Proceedings of

PQA 93, San Diego, CA, November 1993, pp. 5-3:15-3:7.[3] 345 E. 47th St.10 017-2394IEEE recommended practice for harmonic

control in electric power systems, IEEE, New York, NY, IEEE 519,1992.

[4] IEEE Task Force on Modeling and Simulation, Modeling and simula-tion of the propagation of harmonics in electric power networks, PartI: Concepts, models, and simulation techniques, IEEE Transactions onPower Delivery, vol. 11, no. 1, pp. 452465, January 1996.

[5] IEEE Task Force on Modeling and Simulation, Modeling and simula-tion of the propagation of harmonics in electric power networks, Part II:Sample systems and examples, IEEE Transactions on Power Delivery,vol. 11, no. 1, pp. 466474, January 1996.

[6] The Fontaine, Unit 6B, 1220 NE 17th Ave.97232W. S. Meyer,Alternative Transients Program (ATP) Rule Book. Portland, OR:Canadian/American EMTP User Group.

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[7] H. W. Dommel,Electromagnetic Transients Program Reference Manual(EMTP Theory Book): Bonneville Power Administration, August 1986.

[8] D. J. Pileggi, E. M. Gulachenski, C. E. Root, T. J. Gentile, and A. E.Emanuel, Effect of modern compact fluorescent lights on voltagedistortion, IEEE Transactions on Power Delivery, vol. 8, no. 3, pp.14511459, Jul. 1993.

[9] R. H. Galloway et al., Calculation of electrical parameters for shortand long polyphase transmission lines, Proceedings of IEE, vol. 111,no. 12, pp. 20512059, Dec. 1964.

Ward Jewell (M80SM90) teaches courses in electric power systems andelectric machinery as a Professor of Electrical Engineering at Wichita StateUniversity. Dr. Jewell is Director of the WSU Power Quality Laboratory andperforms research in electric power quality and advanced energy technologies.He has been with WSU since 1987.

Dr. Jewell earned the Ph.D. in electrical engineering from Oklahoma StateUniversity in 1986. He received the M.S. in electrical engineering fromMichigan State University in 1980, and the B.S. in electrical engineering fromOklahoma State University in 1979. From 19801984 Dr. Jewell worked withthe Power Systems Technology Program at the Oak Ridge National Laboratory.Dr. Jewells consulting work is in electric power quality troubleshooting andanalysis for commercial, industrial, and utility systems. He also consults inother areas of electric power systems and vehicle power systems.

William L. Miller is presently Manager, Technical Network Support, South-western Bell Telephone Company in Topeka, KS. He has taken courses in elec-tronics and related fields at Wichita State University, University of Wisconsin,and University of West Virginia following two years of Vocational Electronicsat CKAVTS. He has been employed for 24 years, which includes 12 years ofexperience with Inductive Interference. He is the Subject Matter Expert (SME)for the Kansas City Market Center in the areas of electrical protection, inductiveinterference, loop transmission, and dial-up data.

Mr. Miller is the Founder and Chairman of the Midwest Power and Commu-

nications Association.

Tom Casey supervisesthe electrical testing laboratoryat Kansas City Power andLight Company in Kansas City, MO. His duties include the repair and testingof distribution line equipment, tools, and test instruments. He received the B.S.in electrical engineering from the University of Kansas in 1981. For the last 15years he has held various customer service positions at Kansas City Power andLight andwas instrumental in developingthe powerquality program at KCP&L.

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