Department of Engineering , CCSU Northeast Utilities

1 

### 115 KV Power Line Electromagnetic Interference Field Testing

Engineering and Safety Study

Alfred A. Gates , Ph.D., P.E. Department of Engineering, CCSU



### Abstract An engineering and safety study, involving power line electromagnetic interference,

was de veloped and implemented for unmanned aircraft system , UAS, flight next to 115KV power lines. Four unmanned aircraft systems were tested for electromagnetic interference from 115 KV lines. The unmanned aircraft systems were positioned on a platform next to 115KV power lines and support structures.

T he autopilot system of each UAS was tested and evaluated . The test set up

consisted of a multi axis tether platform that each UAS was secured to. The platform allowed the UAS to hover in any orientation at a maximum hei ght of t hree feet from the platform. If the UAS b ecame uncontrollable, the tether system will

prevent the aircraft from crashing and allow the pilot to land the aircraft with no damage to the aircraft or property

, on the platform . The flight test ing was su ccessful

and the four UAS aircraft are capable of flight within t hree feet of 115KV power

lines. This report will review the testing of one of the aircraft, the Draganflyer X4

- P.



### Introduction Currently power line support structures are inspected for dama ge due to wild life habitation, corrosion, weather and vandalism. The current process of support structure inspection involves the use of a bucket truck and crew of highly skilled line workers. To inspect a support structure a bucket truck is driven over t errain that sometimes only four wheel drive vehicles can make it through. In those cases road work is required to enable the bucket truck to make it to the support structure. Next the area next to the support structures will have to be cleared and checked and leveled for a proper foundation to support the support legs from the bucket truck. Finally the support structure can be inspected and a determination made of the quality of each support structure. Another method of support structure inspection

involves personnel climbing the support structure and performing the inspection. Each method is time consuming and potentially dangerous.

A new method of support structure inspection is proposed that involves the use of

unman ned aircraft syst ems, UAS . The UAS would be operated with in visual

distance from a pilot

/operator and observer. A pilot would fly a UAS up to a support structure and hover it in a position within 10 feet of a location that is potentially damaged. The UAS would have a video system on board which wouldDepartment of Engineering , CCSU Northeast Utilities

2 be used to provide a close up view of the support structure potential damage

. The UAS would be flown in GPS position hold mode. The UAS will hold position, whenever the pilot stops using the control sticks on a transmitter. This allows for safe flig ht next to objects such as power line support structures.

The benefits of this procedure are savings in inspection time, reduction in

environmental impact, reduction in personnel required and reduction in equipment necessary for the inspection. Additiona l benefits include the development of a video database of the support structures use as a baseline for comparison

. Also the inspection process time would be significantly reduced.

A n engineering and safety study is necessary to determine if the electromag netic

field interferes with the onboard electronics of UAS aircraft . Also different

airframes and or electrical wiring to the motors of each UAS may change the electromagnetic field around the onboard electronics.

The aircraft selected for this experimen tation is a multicopter specifically called a quadcopter. The quadcopter has four arms supporting motors and propellers, figure

1.0. The Draganflyer X4

- P electronics that would be used for power line inspection are; flight controller, inertial measuring un it, telemetry radio , GPS , receiver and

transmitter radio

, and video transmitter.Department of Engineering , CCSU Northeast Utilities

3 Figure 1.0, Draganflyer X4

- P, Multicopter (Quadcopter) and Transmitter

The make of the UAS aircra ft for testing is a Draganfly and th e model of the

aircraft is the D r aga n flyer X4

- P 1 , figure 1.0 and 2.0

. The X4

- P UAS airframe is made of carbon fiber with a high resistance coating. If the coating is scratched the

resistance of each arm is reduced to 500 Ohms. Also the propellers are made of

carbon fiber and have a similar co ating. A ground control station was also used in the 115 KV power line testing. The ground control station provided the tel emetry
from the aircraft and has an attitude indicator along with a compass heading of the

aircraft. The attitude indicator and magne tic heading indicator can be used to monitor the effects of an electromagnetic field. If a magnetic field interferes with a UAS either the attitude indictor and or the magnetic heading indicator will fail.

This aircraft along with three other aircraft we re tested for electromagnetic

interference with the flight stability and position holding capability. This report

covers the results of the Draganflyer X4

- P aircraft.

F igure 2.0, Draganflyer X4

- P Quadc o pte r Electronics



### 115 KV Power Line Test Platform

P latform tethered flight test were performed using the Draganflyer X4

- P aircraft.

The test apparatus was a wood structure, secured to a non

- grounding power line bucket. The test apparatus allowed the quadcopter UAS to hover in any orientation

a t a maximum a t a height of up to three fee t from the platform, figure 3.0. The test platform can also be suspended from a crane, figure 4.0. The maximum pitch and orDepartment of Engineering , CCSU Northeast Utilities

4 roll angle the tether platform would allow is approximately 45 degrees. The pitch and roll degrees of f

reedom is accommodated by a universal joint gimbal , figure

5.0

. The aircraft can yaw in either direction and the rotation about the yaw axis is

unlimited. This tether platform was designed to constrain the UAS in the event of any type of malfunction. In al l modes of flight the quadcopter will never experience pitch and or roll angles greater than 25 degrees. The platform was tested at another

location to ensure that there was no possibility of damage to the aircraft, platform and nearby property by purposel y orienting the aircraft at pitc h and roll angels greater than 2 5 degrees. Figure 4.0 displays a quadcopter in a tethered hover in the suspended platform.

Figure 3.0, 115 KV Multicopter Test Platform , Mock TestingDepartment of Engineering , CCSU Northeast Utilities

5 Figure 4.0, 115 KV Multicopter in a Suspended Platform and in a Tethered HoverDepartment of Engineering , CCSU Northeast Utilities

6 Figure 5 .0, Universal Joint Gimbal



### Dra g a nflyer X4

- P Airframe Evaluation The Draganflyer X4

- P airframe has been examined for electrical resistance. The

airframe and propellers are made of carbon fiber and are coated with a high resistance coating. The coating was scratched off in places and the resistance was

checked and found to be 500 Ohms. Figure 6 .0 provides an evaluation on the resistance of the Draganflyer X4

- P airframe.Department of Engineering , CCSU Northeast Utilities

7 Figure 6 .0, Resistance Evalu ation , Draganflyer X4

- P



### 115 KV Power Line Test Procedure The test procedure involves securing the test platform onto the top of a bucket, figu re 7 . The multcopter is powered up and the multicopter is hovered on the platform , table 1 . Also the telemetry is checked with the ground control station.

Next the throttle is advanced to a setting slightly less than hover. The ground

control station is checked and o nce all of the systems are operating correctly the multicopter on the test platform is moved within th ree feet of a 115KV power line. At three feet the electromagnetic field is constant and remains constant out to approximately 5 meters (16.4 feet) 2 , figure 8. The telemetry is checked for any

malfunctions. The multicopter is next hovered on the platform a t a height up to

three feet from the platform for approximately one minute. Following the hover the multicopter is landed on the platform and the throttle is set slightly less than hover throttle. The multicopter held in position for approximately 10 minut es. Finally the multicopter is hovered in the fixture for approximately a minute. After that the multicopter is landed on the platform and the throttle is again set to slightly less than hover and the bucket is moved to the ground. Once the bucket is stabi lized on the ground the multicopter is hovered above the platform for several minutes. Throughout this process the ground control station is monitored for any

malfunctions and the video monitor is watched for any abnormal activity from the

multi copter.Department of Engineering , CCSU Northeast Utilities

8 Figure 7. 0, Draganflyer X

- 4P Mounted on the Test Platform

Figure 8.0, Typical Electromagnetic Field around Different Power Lines, National Grid EMF help Line 2Department of Engineering , CCSU Northeast Utilities

9 Table 1 , 115 KV Power Line Test Procedures Install hover platform on bucket and secure m ulticopter Turn on multicopter and ground control station Check telemetry on ground control station Hover multicopter on platform and check telemetry Set throttle slightly below hover throttle and hold Move bucket to position three feet next to 115 KV lines Hover multicopter in place at approximately three feet from platform for one

minute Set throttle to slightly lower than hover power (monitor telemetry and record errors) Wait 10 minutes in position (monitor telemetry and record errors) Hover multicopter for one minute (monitor telemetry and record errors) Land multicopter on platform and set throttle to slightly less than hover power Move bucket back to ground Hover multicopter at three feet over platform for several minutes (mon itor telemetry and record errors) Shut down aircraft and remove platform



### 115 KV Power Line Test Results The 115 KV power line test was performed at Grandville Mass on December 19, 2013, figure 9 .0. The tests were c onducted as planned , table 1, by placi ng the Draganflyer X4

- P on a platfo rm mounted on a bucket, figure 7 .0.

Figure 9 .0, Grandville Mass 115 KV Power Line Support StructureDepartment of Engineering , CCSU Northeast Utilities

10 Photos of the positioning of the bucket next to the 115KV power lines are displayed in figure 10 .0. The platform wit h the Draganflyer X4

- P was positioned in

- between two 115 KV power lines as well as within thr ee feet of a 115 KV power line.

Figure 10 .0, Movement of the Platform within Three Feet of 11 KV Power Lines

Figure 11 .0 provides a picture of the video displa y monitor used to hover the Draganflyer X4

- P on the platform next to the 115 KV power lines. Also the Draganflyer X4

- P ground contr ol station displayed in figure 1 2 .0 was used to monitor the telemetry from the multicopter. During all of the procedure s the ground control station provided normal telemetry output from the multicopter , table 2

. There were no abnormalities due to the electromagnetic field. Also the video displayed normal operations of the Draganflyer X4

- P during all phases of the test.

Figu re 11 .0, Video MonitorDepartment of Engineering , CCSU Northeast Utilities

11 Figure 1 2 .0, Draganflyer X4

- P Ground Control Station

Table 2, Draganflyer X4

- P Telemetry DataDepartment of Engineering , CCSU Northeast Utilities

12 

## Conclusion

A n engineering and safety study was performed for electromagnetic interference

from 115KV lines. The Draganflyer X4

- P was tested on a platform attached to a bucket within three feet of a 115 KV power line. The platform allowed the Draganflyer X4

- P to hover at an altitude of three feet above the platform at any orientation. The telemetry was viewed from a ground control st ation and displayed normal data for the duration of the testing. Also a video system was used to view the Draganflyer X4

- P at all times during the testing. The video also displayed normal operation of the X4

- P during all of the testing phases. The results of the tests indicate that the electromagnetic field at three feet or more from 115 KV power lines does not interfere with the Draganflyer X4

- P controller , inertial measuring unit , magnetic compass, transmitter, receiver or GPS.



## References

1) Draganfly Inc.

, http://www.draganfly.com/uav

- helicopter/draganflyer

- x4es/index.php 2) National Grid EMF help Line

, h ttp://www.emfs.info/Sources+of+EMFs/Overhead+power+lines/Department of Engineering , CCSU Northeast Utilities

13 Appendix A



## C E N T R A L

CONNECTICUT STATE UNIVERSITY

_________________________________
1615 Stanley Street P.O. Box 4010 New Britain, CT 06050

- 4010 www.ccsu.edu

4/16/14

To: Skip Wiegand

AEA 220 UAS

Federal Aviation Administration

Fro m: Alfred A. Gates

Subject: 115KV Line SUAS Line Testing

References: Email From Skip Wiegand Dated 4/8/14

The answers to your questions are:
1) The 115KV Power line Electromagnetic Interference testing was done on Thursday 12/19/13.

The line was energized with a voltage of 115KV and a current flow of 24.9 Amperes.
2) The bucket truck used is a non

- grounded High Voltage (HV) Barhand bucket which is used
for live line maintenance and is tested for work up to 500KV. Bef ore the truck can be used

the bucket is tested to insure there is no leakage to ground by moving the bucket into a
position where it makes contact with the power lines and checking the current flow using a
permanently installed meter at the base of the aer ial lift.

3) All personnel involved with the experimentation were fully qualified high tension line
workers from PAR Electrical Contractors working for Northeast Utilities satisfying all
OSHA requirements.
4) All personnel involved with the experimentation wer e on the ground during all phases of the
testing. No personnel were in the bucket during the experimentation. The quadcopters X4

- P

was mounted to a tethered platform . The hovering flight was controlled by watching a

wireless video monitor from a camera mo unted on a wood pole a ways from the quadcopters,
see figure

. 5) The testing procedure was approved by the supervisor on site and met all safety issues. The
wood platform and tether system was found to be acceptable and did not cause an arc since
the platfo rm is electrically isolated by the Barhand bucket.Department of Engineering , CCSU Northeast Utilities

14 6) For the quadcopter to cause an electrical short, or arc, it would have to be grounded. The
quadcopters was always electrically isolated by the Barhand bucket. If the quadcopter came in contact with a power line nothing would happen to the airframe since the airframe is not
grounded. The quadcopter frame voltage would be come the same as the line voltage in the
event of a contact. This would be similar to a bird landing on a power line.
7) Wood has a very small electrical conductance compared to aluminum, steel and other metals
and carbon fiber. We had to be very careful to not generate current through the platform and
tether system. We also used plastic parts where possible to minimize any current flow.
8) Current flow will occur through conducting bodies such as carbon fiber frames when they are
in the proximity of an electromagnetic field. If we used a conducting platform and tether
system then the current flow through it could of altered our experimental results . This test

addressed the effects of current flow through the quadcopter’s carbon fiber frame in addition
to the electromagnetic field around the power lines.

Quadcopter Tether Test Platform Mounted to Barhand Bucket

Sincerely

Alfred A. Gates

Cen tral CT State University 1615 Stanley Street, New Britain, CT 06050 Copernicus Hall Room 2350920 Phone: ( 860) 301

- 2117

, Email: gatesa@ccsu.edu