UltraTEV Locator Operating Manual Locator/manual... · 2011-10-16 · 7.3.4 Testing Plant Which Can...

UltraTEV Locator Operating Manual

Version E

June 2010

EA Technology Ltd Capenhurst Technology Park

Capenhurst Chester

CH1 6ES UK

Tel: +44 (0)151 339 4181 Fax: +44 (0)151 347 2139

Email: [email protected] Web: www.eatechnology.com

© EA Technology Ltd 2010

EA Technology Ltd UltraTEV Locator Operating Manual E503/L/01/E

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www.eatechnology.com Tel +44(0)151 339 4181

Contents 1 Safety Note ......................................................................................................... 3 2 Operational Note ................................................................................................. 4 3 Non-Intrusive Detection of Partial Discharge Activity .......................................... 5

3.1 General ........................................................................................................ 5 3.2 Airborne Ultrasonic Discharge Activity ......................................................... 5 3.3 Electromagnetic Discharge Activity.............................................................. 6

4 The Partial Discharge Range of Equipment ........................................................ 7 5 UltraTEV Locator Overview............................................................................... 10

5.1 Charging the Unit ....................................................................................... 10 5.2 Turning the Unit On/Off .............................................................................. 11 5.3 System Information Screen........................................................................ 11 5.4 Main Menu ................................................................................................. 11 5.5 Setting up the Unit ..................................................................................... 12

5.5.1 Adjusting Settings ............................................................................... 12 5.5.2 TEV Settings....................................................................................... 13 5.5.3 Ultrasonic Settings.............................................................................. 13 5.5.4 Cable PD Settings............................................................................... 13 5.5.5 Temperature Settings ......................................................................... 13 5.5.6 System Settings.................................................................................. 13

5.6 File Browser ............................................................................................... 14 5.7 Scrolling ..................................................................................................... 14 5.8 Text Input ................................................................................................... 14 5.9 Saving Measurement Data......................................................................... 15 5.10 TEV Measurement Screens ....................................................................... 15 5.11 TEV – Continuous...................................................................................... 16 5.12 TEV – Continuous Pulse Mode .................................................................. 17 5.13 TEV – Dual Probe ...................................................................................... 18 5.14 TEV – Discharge Pattern ........................................................................... 20 5.15 TEV Pulse Count Histogram ...................................................................... 21 5.16 Ultrasonic – Internal Probe......................................................................... 22 5.17 Cable PD.................................................................................................... 23 5.18 Temperature .............................................................................................. 24

6 Function Checker .............................................................................................. 25 7 TEV Measurement Procedure........................................................................... 26

7.1 Background Noise...................................................................................... 26 7.2 Making a Magnitude Measurement............................................................ 26

7.2.1 Notes on Amplitude Measurements.................................................... 27 7.3 Locating Partial Discharge Sites ................................................................ 28

7.3.1 Locating Partial Discharge Sites ......................................................... 28 7.3.2 Notes on Location Measurements ...................................................... 28 7.3.3 Identification of Discharge Sources .................................................... 28 7.3.4 Testing Plant Which Can be Racked Out............................................ 29

8 Ultrasonic Measurement Procedure.................................................................. 31 9 Accessories....................................................................................................... 32

9.1 Ultrasonic Contact Probe ........................................................................... 32 9.2 Flexible Sensor .......................................................................................... 32 9.3 UltraDish .................................................................................................... 33


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10 Guide to Interpretation of UltraTEV Locator TEV Readings .......................... 34 11 Relating TEV Reading (in dB) to Discharge Magnitude (in pC) ..................... 35

11.1 Surface Discharges.................................................................................... 35 12 Instrument Specification ................................................................................ 38

12.1 TEV Measurements ................................................................................... 38 12.2 Ultrasonic Measurements .......................................................................... 38 12.3 Cable Pd Measurements............................................................................ 38 12.3 Hardware ................................................................................................... 38 12.4 Environmental ............................................................................................ 39 12.5 Dimensions ................................................................................................ 39 12.6 Power Supplies .......................................................................................... 39 12.7 Battery Charger.......................................................................................... 39

Maintenance............................................................................................................. 40 13 Calibration ..................................................................................................... 40 14 Waste Electrical and Electronic Equipment Directive (WEEE) ...................... 40 15 Warranty........................................................................................................ 41 16 Notes ............................................................................................................. 42


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1 Safety Note The instrument is designed to detect partial discharge sources in Medium/High Voltage (MV/HV) Plant. If no discharges are detected, this does not necessarily imply that an item of MV/HV Plant is discharge free. Discharge sites often have dormant periods and insulation structures can fail through causes other than those attributable to partial discharges. If discharges of considerable magnitude are detected in plant that is connected directly to the medium/high voltage power system, the authority responsible for the plant should be notified immediately.

Warning The UltraTEV Locator is designed for use at ground potential only. • When testing electrical plant ensure that the metalwork is earthed before taking

any measurements. • Maintain safety clearances between structures at high voltage and the

instrument, its probes and the operator at all times. • Adhere strictly to local safety procedures. • Do not make measurements when there are electrical storms in the vicinity. • Do not make measurements immediately following the energisation of a circuit. • Do not disturb plant during measurements either mechanically (e.g. by shaking

or striking it), electrically (e.g. by increasing the voltage) or physically (e.g. by applying heat).

• Do not operate the instrument or its accessories in an explosive atmosphere. • Mains supply voltages are present within the battery charger. • This unit contains no user serviceable parts, always return to EA Technology or

your local distributor for service and repair.


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2 Operational Note When using TEV based instruments the following points should be noted: 1) Care must be taken where work is performed in tight corners, where the proximity

of other earth planes will affect the reading. If possible maintain a distance of more than 30cm from metal work which runs perpendicular to the sensor faceplate.

2) Strong electromagnetic fields from mobile phones, RF transmitters, VDUs and

un-screened electronics in the frequency range DC to 1GHz can have an effect on the readings. A measure of local fields can be obtained by holding the UltraTEV Locator in free-air at least 1 metre away from any conducting surface.

If you have any specific requirement or operating conditions then please contact: [email protected].


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3 Non-Intrusive Detection of Partial Discharge Activity 3.1 General Partial discharges are electric discharges that do not completely bridge the electrodes. The magnitude of such discharges is usually small; however, they do cause progressive deterioration of insulation that may lead to eventual failure. Non-intrusive partial discharge detection provides a fast and simple to use method for identifying potential sources of insulation failure that could otherwise result in the loss of supply to customers or the endangering of staff or other personnel. A partial discharge emits energy in the following ways:

Electromagnetic: • Radio • Light • Heat Acoustic: • Audio • Ultrasonic Gases: • Ozone • Nitrous oxides

The most practical techniques for non-intrusive testing are based on the detection of the radio frequency part of the electromagnetic spectrum and ultrasonic emissions. 3.2 Airborne Ultrasonic Discharge Activity Acoustic emission from partial discharge activity occurs over the whole acoustic spectra. Audible detection is possible but depends on the hearing ability of the individual. Using an instrument to detect the ultrasonic part of the acoustic spectra has several advantages. Instruments are more sensitive than the human ear, are not operator dependent and operating above the audible frequency, are more directional. The most sensitive method of detection is using an airborne ultrasonic microphone centred at 40 kHz. This method is very successful at detecting partial discharge activity provided there is an air passage between the source and the microphone.


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3.3 Electromagnetic Discharge Activity When partial discharge activity occurs within high voltage switchgear insulation it generates electromagnetic waves in the radio frequency range which can only escape from the inside of the switchgear through openings in the metal casing. These openings may be air gaps around covers, or gaskets, or other insulating components. When the electromagnetic wave propagates outside the switchgear it also impinges on the metal casing of the switchgear producing a transient voltage in the external metal cladding of the switchgear. The Transient Earth Voltage (TEV) is a few millivolts to a few volts and lasts only a short time with a rise time of a few nanoseconds. The partial discharge activity may be detected non-intrusively by placing a probe on the outside of the switchgear whilst the switchgear is in service.


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4 The Partial Discharge Range of Equipment The range consists of the UltraTEV Detector, UltraTEV Plus+, UltraMet Plus+, PD Locator (PDL1), UltraTEV Alarm, PD Monitor (PDM03CF), PD Monitor Plus+, UltraTEV Locator and UltraTEV Monitor.

UltraTEV Detector

The UltraTEV Detector is an easy to use hand-held instrument which combines ultrasonic and Transient Earth Voltage (TEV) detection. The instrument is capable of early detection of both surface and internal partial discharge in electrical switchgear. The UltraTEV Detector can be used as part of a Condition Monitoring regime and also as a personal Safety Tool.

The UltraTEV Plus+ is the ultimate hand held instrument for the detection and measurement of partial discharge in switchgear. Both TEV and surface discharges can be detected and are displayed as numerical values on a colour screen. The instrument also has the ability to display the number of PD pulses per cycle, severity levels, maximum levels for internal discharges, and a numerical value for ultrasonic emissions, which can be heard with the supplied headphones.

UltraTEV Plus+


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PD Locator

The PD Locator can be used in single probe mode for TEV magnitude measurements, or double probe mode to accurately locate the source of PD activity using the time of flight technique. The PD Locator can measure PD magnitude over a large range with high accuracy and is the benchmark instrument for the assessment of partial discharge activity.

The UltraTEV Alarm provides substation monitoring of TEV and ultrasonic activity and gives an alarm indication locally and remotely if there is any significant activity above the UltraTEV alarm levels. The UltraTEV Alarm can have multiple nodes connected to allow full substation coverage. The system also reports on relative humidity and temperature within the substation, when the GPRS communication option is chosen.

UltraTEV Alarm

PD Monitor

The PD Monitor is a twelve-channel instrument capable of monitoring discharge activity of a switchboard for a week or more and recording the results. Due to its sophisticated time of flight circuits this instrument is particularly effective where high background activity is present as it will screen out interference sources. The PD Monitor is also useful for detection of intermittent discharge activity, which is often missed when carrying out a survey with, for instance, the UltraTEV Detector or UltraTEV Plus+.


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The PD Monitor Plus+ provides permanent and semi-permanent substation monitoring. It has all of the capabilities of the PD Monitor and can have up to 255 nodes attached. This provides the ultimate in TEV detection and location with full analysis available, over the internet, from anywhere in the world, providing continuous monitoring of critical assets.

PD Monitor Plus+

UltraTEV Locator

The all-new UltraTEV Locator has all of the capabilities of the PD Locator and more, in a powerful compact package. It can be used to accurately locate the source of PD activity using the time of flight technique. The PD Locator can measure PD magnitude over a large range with high accuracy and is an essential instrument for the assessment of partial discharge activity.

The all-new UltraTEV Monitor provides permanent and semi-permanent substation monitoring. It is the most powerful and versatile system ever developed for monitoring Partial Discharge (PD) activity in HV and MV substation assets. It is capable of monitoring PD activity in up to 250 substation assets simultaneously, including measurement and analysis.

UltraTEV Monitor


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5 UltraTEV Locator Overview

5.1 Charging the Unit Before first use, the unit should be fully charged. Full charging takes approximately 7 hours, however, if the unit is already partially charged this time will be reduced. The unit automatically stops charging once the battery is full. The charging status is indicated by the LED next to the charger socket. • If the LED is off, there is no power from the charger • If the LED is red, the battery is being charged • If the LED is green, the charging is complete • The UltraTEV Locator can be left switched on during charging, however, this will

increase the charging time • Do not take measurements with the unit whilst the charger is plugged in

CH1 TEV Sensor

CH1 Ultrasonic Sensor

Touch-screen Display

On/Off Button

External Sensor Front Panel

TEV Function Checker

Dual Probes

TEV Function Checker

CH2 TEV Sensor with

Magnetic Attachment

Photo Reference 50/60Hz


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5.2 Turning the Unit On/Off Push to turn the unit on. After approximately 15 seconds the EA Technology Logo will appear on screen. To turn the unit off, push . 5.3 System Information Screen After the logo screen, the system information screen is displayed. To skip the system information screen tap the touch screen. The system information screen displays the following information:

• Model Number – The model number • Control S/W Version – The current control software version • User Interface Version – The current user interface software version • Serial Number – The serial number of the unit • Calibration Due – The calibration due date of the unit.

(The unit should be calibrated annually) The system information screen can also be viewed by selecting: Info from the SETTINGS screen. 5.4 Main Menu After the system information screen, the main menu is displayed, as shown below:

Menu items are selected by tapping the touch screen.

• TEV – The TEV measurement screens • ULTRASONIC – The Ultrasonic measurement screen • CABLE PD – The Cable PD measurement screen • TEMPERATURE – The Temperature measurement screen • FILE BROWSER – The File Browser screen • SETTINGS – Allows a user to change settings for the various modes

and to view the system information


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5.5 Setting up the Unit The UltraTEV Locator is preset with default settings in the factory and is ready to take measurements immediately. Some users may wish to modify the settings according to their preferences or procedures. From the main menu, select SETTINGS using the touch screen. The available settings appear in a list under various headings. The list can be scrolled up and down using the arrows on the right of the touch screen:

• TEV Settings – Settings for the TEV measurement screens • Ultrasonic Settings – Settings for the Ultrasonic measurement screen • Cable PD Settings – Settings for the Cable PD screen • Temperature Settings – Settings for the Temperature measurement screen • System Settings – System preferences settings In addition to these settings, there are a number of buttons along the bottom of the screen: Info, -, +, Defaults, Save, Menu. Info – View the system information screen that is displayed at start up - – Decreases a setting + – Increases a setting Defaults – Resets the settings to their factory defaults Save – Saves the setting configurations Menu – Returns to the Main Menu

5.5.1 Adjusting Settings In the SETTINGS screen, use the arrows on the right side of the screen to display the setting to be modified. To select the setting, highlight the value by tapping the touch screen, then change the value using the - and + buttons. Once the setting has been changed to the desired value, press the Save button to save the new configuration.


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5.5.2 TEV Settings

• Red Threshold – Sets the red ‘traffic light’ threshold (default 29dB) • Amber Threshold – Sets the amber ‘traffic light’ threshold (default 20dB) • Trigger Buzzer – Turns the ‘trigger buzzer’ on or off

5.5.3 Ultrasonic Settings

• Red Threshold – Sets the red ‘traffic light’ threshold (default 6dB) • Gain – Adjusts the measurement gain, higher gains allow

measurement of smaller signals (default 100dB) • Recording Length – Sets the duration of the sound recording (default 10

seconds)

5.5.4 Cable PD Settings

• Red Threshold – Sets the red ‘traffic light’ threshold (default 20,000pC) • Amber Threshold – Sets the amber ‘traffic light’ threshold (default

3,000pC) 5.5.5 Temperature Settings

• Red Threshold – Sets the red ‘traffic light’ threshold (default 35ºC) • Amber Threshold – Sets the amber ‘traffic light’ threshold (default 30ºC)

5.5.6 System Settings

• Day – The current Day of the week • Month – The current Month • Year – The current Year • Hour – The Hour of the time of day • Minute – The Minute of the time of day • Button Buzzer - Turns the ‘button buzzer’ on or off


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5.6 File Browser The file browser is accessed either via the main menu or the browse button when saving measurement data. The file browser provides an explorer style view of the measurement data stored on the device and allows this data to be copied to an external USB memory stick. All data is stored in a specific folder structure consisting of a base study name and an equipment name. When transferring files to a USB stick, all folder structures are preserved. In the file browser screen, the current level in relation to the root can be seen at all times across the top of the screen. To change level, use the ‘Back’ and ‘Select’ buttons. Select a folder from the list and then click on the ‘Select’ button to go to that folder. Click on the ‘Back’ button to return to the previous folder. Clicking on the ‘Delete’ button will delete the selection from the internal disk and any data below that in the folder structure. For example, deleting a study will delete the study and any equipment within that study along, with each of the files for each piece of equipment. To copy data to an external USB memory stick, first ensure that a compatible USB stick has been inserted in the USB port on the rear of the device. The screen caption will indicate if a USB device has been detected. Data can be copied at any of the folder levels. Similarly to the delete function, copying a study will also copy all of the underlying equipment folders and the files contained with each of those. Selecting a single file from an equipment folder will copy the single file, although the folder structure will be preserved on the USB device. The file browser also has the provision for the creation of folders. Clicking the ‘Create’ button will create a new folder (providing a valid name is entered and the user does not cancel the input), at the current selected level. 5.7 Scrolling A number of screens incorporate the ability to scroll down the page using the scroll-bar on the right hand side of the screen. Scrolling can be achieved either by pressing the appropriate arrows or ‘thumbing’ the scroll bar in the direction required. The latter option is akin to actually scrolling the page with your thumb. 5.8 Text Input On occasions where user text input is necessary, an on-screen keyboard will be displayed. Touching the text (when the keyboard is displayed) will move the cursor or highlight the text as desired. To finish typing and save the text click on the button marked ‘Done’. Clicking the ‘Back’ button will cancel the changes and return to the previous screen. As well as the standard alpha-numeric characters, there is a set of standard symbols and punctuation characters accessed by pressing the function button labelled ‘Fn’.


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5.9 Saving Measurement Data All measurement data can be saved to a file for later analysis. Data is saved in the universal XML format which can be viewed in any text editor or web browser. This data format can also be imported into applications such as Microsoft Excel. All data must be given a study and equipment name, this information is stored within the data file and also provides the folder structure within which the files exist. To pick an existing study/equipment name, click on the ‘Browse’ button. This will bring up the file explorer screen where the study and equipment can be selected. When saving measurement data, the instantaneous readings when the ‘Save’ button is pressed are saved. The exception to this is the ultrasonic audio recording, this will start recording when the ‘Save’ button is pressed on the save screen not the ultrasonic screen. A slight delay will then occur as the system records the audio. 5.10 TEV Measurement Screens Pressing the TEV button on the touch screen will select the TEV measurement screens. There are a number of different screens to select and the screen used in the previous session will appear initially. The screens available are:

• TEV – Continuous • TEV – Continuous Pulse Mode • TEV – Dual Probe • TEV – Discharge Pattern • TEV – Pulse Count Histogram

By default after start up, the TEV – Continuous screen will appear.


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5.11 TEV – Continuous This screen displays the readings from Channel 1 in a continuous display that is updated every second. This screen is shown below.

• Measurement Mode – Informs the user which mode is currently selected • TEV Reading – Shows the current measured TEV level in dB • Historic Reading – Shows the last 15 measured values on a scrolling

histogram, colour coded as per the traffic light indicator • Traffic Light Display – Shows the status of the current TEV level as either,

Green, Amber, or Red, and is determined in the settings menu. The default settings are the same as the UltraTEV Detector (less than 20 dB = green, 20 - 29 dB = amber, and greater than 29dB = red)

• Maximum Reading – the maximum reading obtained since entering this mode or the maximum being reset

In addition to this information, there are a number of buttons along the bottom of the screen: Reset, Mode, Back, Save, and Menu.

Reset – Resets the maximum reading Mode – Moves to the next TEV screen Back – Moves to the previous TEV screen Save – Saves the current readings Menu – Returns to the Main Menu

Measurement Mode

TEV Reading

Historic Display

Traffic Light Display

Maximum Reading

Battery State


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5.12 TEV – Continuous Pulse Mode This screen displays the more advanced information about the TEV levels detected from Channel 1. This is a continuous display that is updated every second as shown below.

• TEV Reading – Shows the current measured TEV level in dB. This is colour coded as per the traffic light indicator

• Pulses – Shows the pulse count over a 2 second period. The UltraTEV Locator measures pulses over half a second and multiplies this by 4 to provide a comparable readout to the MiniTEV and UltraTEV Plus+

• P/Cycle – Shows the pulses per cycle based on either a 50Hz mains frequency reference signal

• Severity – Shows the short term severity, this is calculated by TEV magnitude (mV) multiplied by the number of pulses per cycle

In addition to this information, there are a number of buttons along the bottom of the screen: Mode, Back, Save, Menu.

Mode – Moves to the next TEV screen Back – Moves to the previous TEV screen Save – Saves the current readings Menu – Returns to the Main Menu


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5.13 TEV – Dual Probe This screen activates the instrument in Dual Probe mode where both TEV probes are active. In addition to dual TEV levels, precedence information is also displayed.

• Channel 1 TEV level – use the + and - buttons on the left to increase or decrease the TEV trigger level shown as a large number

• Channel 2 TEV level – use the + and - buttons on the right to increase or decrease the TEV trigger level shown as a large number

• Channel 1 Trigger – This is indicated by a green rectangle below the TEV level and shows whether the UltraTEV Locator is triggering on Channel 1 at the current TEV level

• Channel 2 Trigger – This is indicated by a green rectangle below the TEV level and shows whether the UltraTEV Locator is triggering on Channel 2 at the current TEV level

• Channel 1 First – This is indicated by a red rectangle below the Trigger indication and appears when Channel 1 is triggered before Channel 2

• Channel 2 First – This is indicated by a red rectangle below the Trigger indication and appears when Channel 2 is triggered before Channel 1

• Trigger Level – This indicates the trigger used for the precedence indication and is either Auto or Manual

The precedence information displayed on the ‘First’ indicators is used to locate the source of the discharge signal. On both sides of the screen there are three buttons: +, Auto, -.

+ – Increases the TEV trigger level Auto – Takes an automatic measurement of the TEV level. This button is

highlighted when the measurement is being taken - – Decreases the TEV trigger level

The buttons on the left side of the screen control Channel 1, the left probe, and the buttons on the right side of the screen control Channel 2, the right probe.


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In addition to these functions, there are a number of buttons along the bottom of the screen: Auto / Manual, Test, Reset, Mode, Back, Save, Menu.

Auto / Manual – Toggles the precedence trigger from Auto to Manual Test – Activates the test pulse at the sides of the instrument Mode – Moves to the next TEV screen Back – Moves to the previous TEV screen Save – Saves the current readings Menu – Returns to the Main Menu


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5.14 TEV – Discharge Pattern This screen displays the discharge pattern on a mains cycle time base (20 milli-seconds) for Channel 1. To use this feature, the 50Hz mains reference source must be connected to the instrument or the photo sensor must be able to pick up a reference from mains powered lights. The time base is split up into forty slots and will indicate if a trigger has been detected in this slot over the update period. The display is then updated every second.

• To adjust the TEV level, use the ‘+’ and ‘-’ buttons on the right to increase or decrease the TEV trigger level shown in the centre of the screen

• The discharge pattern on a mains cycle is shown beneath the trigger level; the horizontal axis represents the time base and is marked at 0, 90, 180, 270 and 360 degrees. Triggers are shown as vertical lines along the time base

On the right hand side of the screen there are two buttons: + and -.

+ – Increases the TEV trigger level - – Decreases the TEV trigger level

In addition to these functions, there are a number of buttons along the bottom of the screen: Mode, Back, Save, Menu.

Mode – Moves to the next TEV screen Back – Moves to the previous TEV screen Save – Saves the current readings Menu – Returns to the Main Menu


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5.15 TEV Pulse Count Histogram This screen displays a histogram to TEV pulse magnitude on the x axis against pulse per cycle on the y axis.

This screen can be useful to identify more than one discharge at different levels and different pulse rates. In particular a high pulse rate discharge can be masked by a lower rate higher magnitude discharge.


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5.16 Ultrasonic – Internal Probe The Ultrasonic Measurement screen is shown below:

• The ultrasonic reading is displayed in dB microvolts (dBμV) • The ‘traffic light’ display indicates if the reading is above the threshold set in

the Ultrasonic Settings menu. The default value is the same as the UltraTEV Detector, i.e. > 6dB = RED

• The gain can be adjusted from 60 to 100 dB in 20dB steps using the ‘G-’ and ‘G+’ buttons at the bottom of the screen. If an arrow pointing up appears next to the gain value, increase the gain setting to improve the accuracy of the reading. If an arrow pointing down is displayed, decrease the gain accordingly

• The volume of the heterodyne signal supplied to the headphones can be adjusted by sliding the scroll bar to the level required

• The filter frequency can be set to either 25kHz or 40kHz depending on the external sensor being used. The filter frequency can be changed using the ‘Mode’ button at the bottom of the screen

In addition to these functions, there are a number of buttons along the bottom of the screen: G-, G+, Mode, Save, Menu.

G- – Decreases the gain G+ – Increases the gain Mode – Changes the filter frequency Save – Saves the current readings Menu – Returns to the Main Menu


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5.17 Cable PD The Cable PD measurement screen is shown below:

• PD Reading – Shows the current measured discharge level in pC • Historic Reading – Shows the last 15 measured values on a scrolling

histogram, colour coded as per the traffic lights • Traffic Light Display – Shows the status of the current discharge level as

Green, Amber, or Red, and determined by the settings • Maximum Reading – the maximum reading obtained since entering this

mode or the maximum being reset In addition to these functions, there are a number of buttons along the bottom of the screen: Reset, Save, Menu.

Reset – Resets the maximum reading Save – Saves the current readings Menu – Returns to the Main Menu


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5.18 Temperature The temperature measurement screen is shown below. To use this feature the non-contact temperature sensor must be connected to the instrument.

• Temperature Reading – Shows the current temperature on the non-contact temperature sensor in degrees Celsius

• Traffic Light Display – Shows the current temperature as Green, Amber, or Red, determined by the settings

• Maximum Reading – Shows the maximum reading obtained since entering this mode or the maximum being reset

• Pressure - Shows the ambient barometric pressure in millibars

• Dew Point - Shows the dew point associated with the ambient temperature and humidity

• Ambient Temperature – Shows the ambient temperature around the instrument in degrees Celsius

• Humidity – Shows the relative humidity around the instrument as a percentage

In addition to this information, there are a number of buttons along the bottom of the screen: Reset, Save, Menu.

Reset – Resets the maximum reading Save – Saves the current readings Menu – Returns to the Main Menu


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6 Function Checker UltraTEV Locator is supplied with built in function checkers. The purpose of these is to verify the UltraTEV Locator is operational before taking a measurement on any switchgear. Note: It is not intended to check the calibration of the instrument.

The function checker consists of two plates, one on either side of the instrument located behind the label marked ‘probe test point’. A test pulse can be applied to the plates in order to confirm the operation of the instrument. To check whether the UltraTEV Locator is operating correctly, switch the instrument on and select the TEV – Dual Probe screen. Connect both probes to the instrument and activate the test pulse by tapping ‘Test’ at the bottom of the screen. Place the probes firmly against the sides of the instrument and adjust the levels on both probes to achieve a consistent trigger on both channels. The trigger level should be approximately 38dB ± 4dB with one channel triggering first. Note due to the signal paths when two probes are used the magnitudes will vary from those measured with only one probe. If the probes are then swapped over, the opposite channel should trigger first.

Switch off the test pulse with the ‘Test’ button. It is recommended that the UltraTEV Locator is checked before each use.


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7 TEV Measurement Procedure 7.1 Background Noise Electromagnetic signals from external sources can also induce transient earth voltages on the outside of the switchgear. These sources may be overhead line insulators, transformer bushings, strong radio signals, and even traffic on a nearby Motorway. These sources subsequently produce TEV signals on metalwork that is not connected to the switchgear, such as metal substation doors or fencing. This background noise must therefore be measured on such surfaces before any measurements are made on the switchgear. If the background noise is <10dB then the UltraTEV Locator pulse counter is not incremented and will read zero. Measure the background noise level on a piece of metalwork that is not part of or connected to the switchgear, (e.g. a metal door, a metal fence). Record three consecutive dB values and counts on the metalwork and then take the mean amplitude reading as the background measurement. 7.2 Making a Magnitude Measurement Switch the instrument on and select ‘TEV’ on the touch screen and then put the instrument into TEV – Continuous mode using the buttons on screen. Connect a probe to Channel 1. To take a measurement hold the TEV probe squarely in contact with the metalwork on which the measurement is to be taken (preferably keeping the probe body away from neighbouring metalwork as shown below). The unit will display the TEV reading on the screen and the historic readings on the scrolling histogram.

Correct Incorrect

Other single probe modes available include: TEV – Continuous Pulse Mode TEV – PDL Mode TEV – Discharge Pattern


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Measurements on switchgear are made at the centre of each component of each panel e.g. cable box, CT chamber, busbar chamber, circuit breaker or VT. The position of the circuit breakers or other MV/HV switches should be recorded, because if these are in the off position, certain components will not be energised and therefore readings will not be valid on such components. Record the first set of readings at each switch position unless the measurement amplitude is greater than 10dB above the background, and greater than 20dB, 50 counts. If this is the case, record three consecutive sets of readings. 7.2.1 Notes on Amplitude Measurements 1. At least one measurement should be made per panel on an extensible type switchboard. If signals of significant magnitude are detected on a panel, further measurements should be made to establish where the signal strength is a maximum. 2. Measurements on cable sealing ends (i.e. where a cable is terminated for connection to an overhead line, or to plant with exposed high voltage conductors) should normally be made with the probe about 1.5m above ground level. 3. As the magnitude of TEV signals reduces rapidly with distance travelled, a rough location of a discharge site will be given by the position of the largest signal. Within 5 metres of the site however, local maxima can occur due to constructive interference between the signal and its reflections. 4. For more accurate measurements, the discharge site should be located by comparing the arrival times of the transients at different points. This is achieved by using the UltraTEV Locator in the double probe mode as described in following section.


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7.3 Locating Partial Discharge Sites Before attempting to use the UltraTEV Locator on items of plant, operators should familiarise themselves with the equipment. The following text assumes that the operator is familiar with the functions of the controls on the instrument. 7.3.1 Locating Partial Discharge Sites 1. Set the instrument to TEV – Duel Probe mode. Place the probes on the test specimen at least 600mm apart and press the 'Auto' buttons on both probes. 2. On completion of the auto magnitude measurement ‘Trigger’ should flash simultaneously under both readings and the leading channel should be indicated by ‘First’ on screen. Note: To obtain satisfactory triggering, it may be necessary to reduce the attenuator settings by a few dB's. Moving the probes should quickly establish where the discharge source is located. 7.3.2 Notes on Location Measurements When locating discharges, it is important that the operator takes into consideration the possible signal paths. For example, when tests are made on cable sealing ends, the external TEV mode signals always travel along the outside of the cable sheath away from the termination regardless of whether the discharge source is in the sealing bell or in the cable. This is a consequence of the high frequency skin effect that restricts high frequency currents to a thin layer on the surface of conductors. The signals cannot travel through the thickness of the cable sheath. Instead they must travel to the base of the sealing bell before transferring to the outside of the cable sheath and travelling back, along the outside of the cable, to ground. 7.3.3 Identification of Discharge Sources The various types of discharge site exhibit characteristic patterns of behaviour in terms of signal amplitude and time of occurrence relative to the phase of the high voltage supply. The TEV – Discharge Pattern mode can be used to help identify the discharge type. It must be noted that the phase relationship between the mains reference signal and the discharge source in general will not be known, therefore the assessment must be made on the pattern. Tests for discharges in cable sealing ends can be frustrated by corona discharges from sharp projections on components such as arcing horns and conductor clamps. If the discharges are found to occur repeatedly, in quick succession, around the peak negative voltage of the high voltage supply, and nowhere else during the cycle, and the discharges are all of similar amplitude, this is indicative of corona from a sharp projection on a component at high voltage. If the discharges occur around the


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positive peak, the corona is associated with a sharp projection on the 'earthy' side of a discharge gap. If the absolute phase is not known, it will not be possible to distinguish between these two options but the presence of a corona source will still be apparent. If these are the only discharges detected, no further tests need be made and the circuit can remain in service. Discharges between two insulating surfaces (e.g. in a void within the insulation) generally show considerable variation in amplitude between events. They occur in two parts of the cycle starting before each zero voltage crossing and finishing just before the ensuing voltage maximum. Within these time slots, their occurrences can be fairly random. The behaviour is similar for both time slots. Discharges between an insulating and a metallic surface (e.g. at a poorly fitting electrode) exhibit similar characteristics but there is asymmetry between the positive and negative going time slots. Discharges between two metallic surfaces (e.g. between the earth foil of a capacitor bushing and its connecting plug) are, generally larger in amplitude and more regular in terms of amplitude and timing. If one side of the discharge site has a small external radius and the other is relatively flat (e.g. a piece of metallic swarf adjacent to, but not in electrical contact with, the chamber of a gas insulated switchboard or, at the edge of a stress grading foil in a capacitor bushing), the discharges exhibit strong asymmetry between the positive and negative going cycles. A poor electrical contact is easily recognised because it generates a large number of discharges when the current is a maximum. This is most likely to occur when the item under test is being energised from a test transformer. Note: The item under test will normally be reactive and so the current will be a maximum around the voltage zeros. 7.3.4 Testing Plant Which Can be Racked Out A problem can occur in identifying the source of discharges when testing plant which can be racked out, such as circuit breakers, voltage transformers, etc. If discharges are found on this type of plant, it is possible to arrange for the item to be isolated by racking it out to determine whether the discharges are in the plant item or are coming from the busbar chamber. In particular, it may be necessary to determine whether a discharge site is in the plug bushing of the circuit breaker or the orifice bushing of the busbar chamber. A discharge site in the orifice bushing may remain active if the plug bushing is withdrawn and it might therefore be expected that the level of discharge on the busbar chamber would be unaffected when the circuit breaker is racked out if the source is in the orifice bushing. However, this is not the case. When the plug bushing is disconnected from the orifice bushing, there is no central conductor at the outer end of the orifice bushing. A short length of circular wave-guide will therefore be created which will appear as an open circuit to all signals below it's cut off frequency.


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The effect of this is to reflect internal discharges generated in the orifice bushing back into the bushing, preventing them from being detected externally. It will therefore appear that the discharge source is in the circuit breaker as the discharge on the busbar will have disappeared. If this situation occurs, it will be necessary to carry out separate HV tests using a test transformer to energise the circuit breaker under standard HV test safety procedures.


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8 Ultrasonic Measurement Procedure Ultrasonic activity above the background levels may be a significant indication of partial discharge. Genuine discharge can be identified by a crackling sound (similar to a sizzling frying pan), through the headphones. Turn on the unit and select Ultra Mode from the menu. Plug in the supplied headphones and adjust the volume. The reading will continuously update on screen. A measurement of the background noise should be taken within the substation. This is done by pointing the probe away from any direct ultrasonic sources, such as switchgear and fluorescent lighting, and taking a measurement. Record three consecutive sets of readings and take the mean amplitude reading as the background measurement. To survey the switchgear, point the ultrasonic sensor towards any air gaps, particularly breaker spouts, air filled cable boxes, VT and busbar chambers. Set the gain to maximum initially and reduce the gain if the readings are too high. Note: appropriate safety distances must be maintained at all times. To convert from dBµV to dB SPL (sound pressure level) subtract 19dB from the reading.


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9 Accessories

9.1 Ultrasonic Contact Probe The Ultrasonic Contact Probe is provided to enable discharges to be detected in enclosed areas where there is no direct air path from the discharge source to the sensor. The Probe connects to the external sensor connector and is clamped on to the area or interest using the magnets surrounding the sensor plate. The probe will detect discharge sources inside the enclosed area by detecting the energy transmitted to the enclosure. Care must be taken to eliminate other sources that could cause the signals from discharges to be masked, e.g. accidental movement of the probe itself.

9.2 Flexible Sensor The Flexible Sensor provides a means of reaching inaccessible parts on the switchgear. The sensor is mounted at the end of a flexible goose-neck which allows the angle of the sensor to the handle to be adjusted. This allows the user to make measurements where it would be difficult to use the built in sensor and still be able to read the display.


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9.3 UltraDish The UltraDish provides a means of detecting discharge sources at a distance. It comprises a transparent parabolic reflector that focuses the ultrasonic sound on to a sensor mounted at the focus point of the reflector. The UltraDish gives an effective increase in gain compared to the built in sensor. The UltraDish can be aimed at the target by using either the optical sight or the built in laser pointer activated by a switch on the handle.


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10 Guide to Interpretation of UltraTEV Locator TEV Readings

TEV Reading

Conclusion

1. High background reading, i.e. greater than 20dB.

(a) High levels of background noise can

mask discharges within the switchgear (b) Possibly due to an external influence.

If possible remove the external source and re-test alternatively re-survey using the PD Monitor to identify any discharges in switchgear.

2. If all the readings on the switchgear and the background reference are less than 20dB.

No significant discharging. Re-survey annually.

3. For switchgear readings greater than 10dB above the background and if the reading is greater than 20dB (absolute), i.e. not 20dB above the background level, and is more than 50 counts.

Strong possibility of internal discharge activity within the switchgear. Recommend further testing using the PD Locator or PD Monitor.

4. For readings with a count rate greater than 1000.

There may be transmitted background electromagnetic activity in the region. If the readings are greater than 20dB then it is recommended that a PD Monitor be installed to identify external electromagnetic activity. A high count rate may be caused by surface discharges. If this is the case, ultrasonic emissions will be present which can be detected with the UltraTEV Locator, provided an air path is present.


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11 Relating TEV Reading (in dB) to Discharge Magnitude (in pC) Conventional Partial Discharge detection according to IEC60270, measures the apparent charge transfer from the high voltage conductor system when a discharge occurs. Thus the discharge magnitudes are normally expressed in pico-coulombs (pC). At the detection frequencies used by conventional PD detectors (typically 10 - 300 kHz), all items of high voltage plant, with the exception of long cables, can be considered to be lumped capacitors. The TEV measurement works over the frequency range 3 - 100MHz. At these frequencies high voltage power plant items behave similarly to transmission lines rather than capacitors. The area under the voltage/time curve would be proportional to the charge transfer during the discharge process. TEV sensors measure the peak voltage of the detected transient, rather than the area under the curve. Therefore, it does not measure the charge directly. Furthermore, it is the peak of the wave detected on the external surface of the metal-cladding that is measured and this will be a fraction of that within the cladding. As the pulse travels along the external surfaces of the metal-cladding it disperses, i.e. spreads out. This has the effect of reducing the peak amplitude whilst maintaining the area under the curve. Therefore, the further away from the discharge source the pulse is detected, the greater the attenuation. Clearly the relation between dB and pC is dependent on many factors, most of which are difficult to quantify. Some recent laboratory tests undertaken by an independent party, and field measurements undertaken by EA Technology, on various system components, combining both conventional discharge detection and TEV measurements, yielded the results detailed in the tables on pages 36 and 37. 11.1 Surface Discharges The most successful way of detecting surface discharges is using ultrasonic techniques. Surface discharges produce very low TEV signals compared to internal discharges. In addition, the electromagnetic signals produced by surface discharges are lower in frequency than the operating band of the TEV instruments. This is due to the slower rise times of the waveforms. In many cases the signals will not be picked up by TEV only instruments as they will be lower than the ambient noise levels.


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Table 1 dB-pC guidance for 25kV close to termination

TEV Reading (dB)

PD Conventional Measurement (pC)

0 32 5 56

10 100 15 178 20 316 25 560 30 1,000 35 1,780 40 3,160 45 5,600 50 10,000 55 17,800 60 31,600

Table 2 gives some empirical results for a phase to earth discharge in a compound-filled 11kV cable end box. Table 2 dB-pC guidance for compound-filled 11kV distribution cable end box

TEV Reading (dB)


0 100 5 178

10 316 15 562 20 1,000 25 1,780 30 3,160 35 5,620 40 10,000 45 17,800 50 31,600 55 56,200 60 100,000


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Table 3 gives some empirical results for a phase to earth discharge in a SRBP bushing in an Oil Circuit Breaker. Table 3 dB-pC guidance for SRBP Bushing in Oil Circuit Breaker

TEV Reading (dB)


0 134 5 239

10 423 15 753 20 1,340 25 2,390 30 4,230 35 7,530 40 13,400 45 23,900 50 42,300 55 75,300 60 134,000

Table 4 gives some empirical results for an internal discharge in a Cast Resin CT at 11kV. Table 4 dB-pC guidance for Cast Resin CT at 11kV

TEV Reading (dB)


0 224 5 399

10 708 15 1,260 20 2,240 25 3,990 30 7,080 35 12,600 40 22,400 45 39,990 50 70,800 55 126,000 60 224,000

It must be stressed that the tables above should only be used as a rough guide. Whilst it is generally correct that increasing pC levels equates to increasing dB levels, factors such as the source of the discharge activity and the attenuation path all have significant influence on calibrating results.


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12 Instrument Specification 12.1 TEV Measurements Sensor: Capacitive Measurement Range: 0 – 60dBmV Resolution: 1dB Accuracy: ±1dB Max Number of Pulses/Cycle: 655 Min Pulse Rate: 10Hz 12.2 Ultrasonic Measurements Measurement Range: -7dBµV to 68 dBµV Resolution: 1dB Accuracy: ±1dB Transducer Sensitivity: -65dB (0dB = 1volt/µbar rms SPL) Transducer Centre Frequency: 40 kHz Transducer Diameter: 16mm Heterodyning Frequency: 38.4 kHz 12.3 Cable Pd Measurements Sensor: RFCT Measurement Range: 0 – 25,000pC Resolution: 98pC Accuracy: 98pC Min Pulse Rate: 10Hz 12.3 Hardware Enclosure: Self-coloured injection moulded plastic case Indicators: Colour back-lit LCD Charging indicator LED Controls: Membrane keypad Connectors: TEV/Ultrasonic Lemo mixed socket

TEV Lemo mixed socket Cable PD BNC socket External Ultrasonic sensor Lemo multipole socket Non-contact temperature sensor Lemo multipole socket 3.5mm stereo headphone socket USB 1.1 port 2.1mm 18V Charger Input 1.3mm 9V AC mains reference input

Headphones: Min. 8 ohms


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12.4 Environmental Operating Temperature: 0 – 55 degrees C Humidity: 0 – 90 % RH non-condensing IP Rating: 30 12.5 Dimensions Size: 240mm x 140mm x 140mm Weight: 1.7kg 12.6 Power Supplies Internal Batteries: 3.7V 13.6Ah Lithium-Ion Typical Operating Time: approx. 5 hours Battery Conservation: Automatic ‘switch off’ when low battery voltage

detected. 12.7 Battery Charger Rated Voltage: 90 – 264V AC Frequency: 47 - 63Hz Charging Voltage: 18V DC Charging Current: 2500 mA Time for Full Charge: 7 hours Dimensions: 74mm x 44mm x 34 mm Weight: 0.12 kg Operating Temperature: 0 - 40 degrees C Humidity: 20 – 85% RH non-condensing


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Maintenance It is important that the unit is kept clean and dry. It is not weatherproof. Avoid storage in damp and humid conditions and do not subject it to temperature extremes, excessive vibration or shocks. Do not stand on the case. Internal, rechargeable batteries power the instrument. No attempt should be made to gain access to the internal circuitry of the instrument, or its accessories. Advice should be sought from the manufacturer, or the supplier, if any doubt exists over the equipment's performance or operation. The unit should be cleaned with a damp cloth. If more heavily soiled, a foam cleanser may be used, provided care is taken not to allow fluid to enter the instrument. Abrasive cleaners must not be used. Take care not to scratch the plastic overlay of the front panel, especially in the area of the LCD window.

13 Calibration The recommended calibration interval of 12 months is based on EA Technology’s experience with this product. Your application may require a different calibration interval dependant on the frequency of use. The calibration interval should begin on the date the instrument is placed in service. Proper storage prior to being placed in service will not affect the recommended calibration interval.

14 Waste Electrical and Electronic Equipment Directive (WEEE) EA Technology is a member of an approved compliance scheme as defined by the WEEE directive. When the product reaches the end of its operational life it must be recycled by a licensed waste management operator, or alternatively be returned to EA Technology for recycling.


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15 Warranty EA Technology products are warranted against defects in material and workmanship for twelve months from the date of shipment. The battery and accessories (charger, cables, etc.) are guaranteed for a period of twelve months. During the warranty period, EA Technology will, at its option, either repair or replace units that prove defective. For warranty service and repair, products should be returned to EA Technology at the address above. It is the purchaser’s responsibility to return the faulty product to EA Technology and is at their cost. Repaired/replacement products will be returned at the cost of EA Technology. The warranty shall not apply to defects caused by improper maintenance, modification or misuse. Warranty Extension All registered products will receive an additional 12 months warranty free of charge. To register your product visit: www.eatechnology.com/business/instruments Note EA Technology has a policy of continual product development and enhancement. While every effort has been made to ensure the accuracy of this document, there may be minor variations between the details given and the equipment supplied. EA Technology Ltd Capenhurst Technology Park Capenhurst Chester CH1 6ES UK Tel: +44 (0) 151 339 4181 Fax: +44 (0) 151 347 2139


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