Download
Share
Print this page
  1. Manuals
  2. Brands
  3. Tettex Manuals
  4. Medical Equipment
  5. MIDAS micro 2883
  6. Operating instructions manual

Tettex MIDAS micro 2883 Operating Instructions Manual

Mobile insulation diagnosis & analysing system
Hide thumbs

Advertisement

Quick Links

Download this manual
Operating Instructions
HAEFELY TEST AG
MIDAS micro
2883
Mobile Insulation
Diagnosis &
Analysing System
Version 1.4
4843122

Advertisement

loading
Need help?

Need help?

Do you have a question about the MIDAS micro 2883 and is the answer not in the manual?

Questions and answers

Subscribe to Our Youtube Channel

Summary of Contents for Tettex MIDAS micro 2883

  • Page 1 Operating Instructions HAEFELY TEST AG MIDAS micro 2883 Mobile Insulation Diagnosis & Analysing System Version 1.4 4843122...
  • Page 3 Title Operating Instructions MIDAS micro 2883 Date 11-2014 Authors TH, DL, LWA Layout Revision History Version Date Author Remarks 06/2014 DL TH Initial release of the document 11/2014 PF formula modified 02/2015 Changes for firmware V1.1.0 and V1.1.1 03.2018 FTP Server and Limits added...
  • Page 4 WARNING Before operating the instrument, be sure to read and understand fully the operating instructions. This instrument is connected to hazardous voltages. It is the responsibility of the user to ensure that the system is operated in a safe manner. This equipment contains exposed terminals carrying hazardous voltages.

  • Page 5: Manual Conventions

    Manual Conventions In the manual, the following conventions are used: Indicates a matter of note - if it refers to a sequence of operations, failure to follow the instructions may result in measurement errors. Indicates hazards. There is a risk of equipment damage or personal injury or death. Carefully read and follow the instructions.

  • Page 6: Table Of Contents

    Contents Manual Conventions....................VI Abbreviations and Definitions ..................VI Introduction General ........................1 Scope of Supply ......................1 Technical Data Safety General ........................5 Personnel Safety ......................5 Safety Features ......................6 Safety Precautions ..................... 6 Summary........................7 Theory Why is Insulation Tested? ..................8 What is Loss Factor? ....................
  • Page 7 Front-Panel Features ....................23 7.1.1 Ground Terminal ..................24 7.1.2 Ventilation Slots ..................24 7.1.3 High Voltage Output .................. 24 7.1.4 Emergency Stop Button ................24 7.1.5 Low Voltage Point V .................. 24 7.1.6 Measuring Input HV GND ................24 7.1.7 Measuring Input A ..................
  • Page 8 11.1.2 Test Settings ..................... 52 11.1.3 Measured Values Area ................52 11.1.4 Special Symbols in Measurement Values ..........53 11.1.5 Toolbar ...................... 53 11.1.6 The Tools Menu ..................54 11.1.7 The File Menu ................... 56 11.2 Sequence Tab ......................57 11.2.1 Setting up a Sequence ................
  • Page 9 15.2.1 Foot Switch ....................90 15.2.2 Safety Strobe Light ..................90 15.2.3 External Temperature Probe ..............90 15.2.4 Thermo-Hygrometer .................. 90 15.2.5 Adapter LEMO to BNC ................90 15.2.6 Hook for HV Cable ..................91 15.2.7 Set of Hot Collar Tests ................91 15.2.8 Midas Office software ................
  • Page 10 20.7.1 Test Levels....................123 20.7.2 Test Procedures ..................123 20.7.3 Measuring Data Interpretation ..............124 Introduction...

  • Page 12: Introduction

    Introduction General The MIDAS micro 2883 is the smallest, most compact insulation tester on the market. It is designed for power / dissipation factor and capacitance testing in the field and in the factory. Scope of Supply The following items are supplied with a standard single channel system: Part No.
  • Page 13 Mains cable A country specific mains cord is also delivered inside the accessories bag. Part No. Description 0937401 USA / Japan, 2.0m, 10A 0938201 Switzerland; 2.0m, 10A 0938561 UK, 2.5m, 10A 0194091 China, 2.5m, 10A 0938251 Europe (Schuko), 2.5m, 10A Optional accessories (not included in standard scope of supply): Part No.

  • Page 14: Technical Data

    Technical Data Measurement System Range Resolution Accuracy Dissipation Factor ± 0.5 % rdg ±0.0001 @ 0 .. 100 0.0001 (tan δ) (0 .. 99’999%) 0.01 % 50..60 Hz ± 0.5 % rdg ±0.01% @ 50..60 Hz Power Factor ± 0.5 % rdg ±0.0001 @ 0 ..
  • Page 15 Calibration Interval 2 years recommended Interfaces Display 7” TFT , 800 x 480, Colour Touch Screen Measurement 3 x BNC Inputs 1 x USB 2.0 Ethernet/LAN 1 x RJ-45 Safety Features Open Ground Detection Security Handheld Switch, Foot Switch Warning Lamp Audible Warning Signal on High-Voltage ON Measured Values DF (tan δ)

  • Page 16: Safety

    Do not switch on or operate a MIDAS micro 2883 instrument if an explosion hazard exists. Personnel Safety The MIDAS micro 2883 should not be operated by a crew smaller than two people. Their function can be described as follow: Test Operator: The person who is making the test connections and operates the MIDAS micro 2883.

  • Page 17: Safety Features

    A separate green/yellow earth cable is provided for the purpose of safety grounding the instrument. The earth cable should be connected to the Earthing Screw on the front panel of the MIDAS micro 2883 at one end and to the station grounding system at the other end.

  • Page 18: Summary

    This entail a second important rule - all terminals of a device under test should be completely isolated. Finally it should be noted that the MIDAS micro 2883 is relatively lightweight. It can be lifted by a single person. We recommend however that you lift it carefully and ergonomically in order to prevent injuries.

  • Page 19: Theory

    Theory Why is Insulation Tested? All transformers, high voltage switchgear, motors and electrical equipment accessories have a high voltage lifespan. From the first day of use the equipment is subject to thermal and mechanical stresses, foreign particle ingress and variations in temperature and humidity. All of these influences raise the working temperature of the equipment when switched on.
  • Page 20 ε ⋅ where: electrode face distance between the electrodes capacitance ε dielectric constant of air (ε =8,8542•10 F/m) ε relative dielectric constant dependent upon material ε ε = ε • ε Disc Capacitor , dielectric constant In an ideal capacitor the resistance of the insulation material (dielectric) is infinitely large. That means that, when an AC voltage is applied, the current leads the voltage by exactly 90°.

  • Page 21: The Difference Between Power Factor And Dissipation Factor

    The Difference between Power Factor and Dissipation Factor While “Dissipation Factor” tan δ is used in Europe to describe dielectric losses, the calculation used in the United States is „Power Factor“ cos ϕ. The statistical data that have been collected in North America have been calculated using the loss factor cos ϕ (Power Factor) to specify the power losses in the insulation.

  • Page 22: Test Instruments

    Test Instruments There are three basic kinds of capacitance, tan δ and power factor test instruments in use. Although the high accuracy Schering Bridge must be balanced manually and the balance observed on a null indicator, it has been widely sold and used for decades. The capacitance and dissipation factor can be calculated by reading the position of the balance elements.

  • Page 23: Dissipation Factor Of Typical Apparatus Insulation

    An increase of dissipation factor above a typical value may indicate conditions such as those showed above: If the dissipation factor varies significantly with voltage down to some voltage below which it is substantially constant, then ionization is indicated. If this extinction voltage is below the operating level, then ionization may progress in operation with consequent deterioration.

  • Page 24: Influence Of Temperature

    Silicone liquid 0.001% Varnished cambric, dry 1.0% Water 100% 1.0% @ 0°C Note: Tests for moisture should not be made at freezing temperatures because of the 100 to 1 ratio difference dissipation factor between water and ice. 5.7.4 Influence of Temperature Most insulation measurements have to be interpreted based on the temperature of the specimen.

  • Page 25: Influence Of Surface Leakage

    It is also possible that a negative dissipation factor reading may be obtained so it is necessary to observe the polarity sign for each reading. The MIDAS micro 2883 interference suppression feature minimizes the influences but however, the influences may be minimized considerably by: •...

  • Page 26: Standard Capacitor, Measuring Current & Limits

    Standard Capacitor, Measuring Current & Limits To evaluate the expected values of test current, standard capacitor current, the corresponding limiting parameters and the resulting load range use these basic conditions and rules: (1) Maximum test voltage shall be less than the nominal ≤...

  • Page 27: Parallel & Series Equivalent Circuits

    ⋅ ⋅ ⋅ − Test Parallel & Series Equivalent Circuits The MIDAS micro 2883 measures the parallel equivalent circuit values. The following formulas describe the calculation of the value conversion parallel – series : ω δ ⋅ ⋅ * measured values Parallel equivalent circuit C δ...

  • Page 28: Functional Description

    System Overview To be able to execute correct and reproducible measurements it is essential to understand how the MIDAS micro 2883 measuring system works. The MIDAS measuring system is based on the double vector-meter method which relies upon the measurement of...

  • Page 29: Test Modes

    To keep in mind for the user of the system is that capacitances related to the V-point are bypassed. Make sure that all unwanted capacitances are related to the V-potential point and their current is flowing directly into the V- point and not through the measuring shunt R This has to be evaluated for every measuring setup.
  • Page 30 measurements. This involves a lot of work and time, especially when on-site measurements are being performed on large power transformers. Using the different Test Modes, the test object only has to be connected once for measurement and all relevant capacitances can be measured by switching the connections as required. The selected Test Mode connects the DUT current path(s) to the internal current measuring shunt R and the other (not measured) connected leads to the V-potential (reference point) of the system.

  • Page 31: Test Mode „Ust" For Ungrounded Test Objects

    6.3.1 Test Mode „UST” for ungrounded test objects This test mode is the most common situation when measuring capacitance and dissipation factor. Various ungrounded capacitances can be measured using this mode, providing that the maximum test current of the measuring instrument is not exceeded. When measuring power transformers and HV current transformers, this configuration determines the capacitance and dissipation factor between the various winding groups.

  • Page 32: Test Mode „Gst G" For Grounded Test Objects With Guarding (V-Potential)

    6.3.3 Test Mode „GST g“ for grounded test objects with guarding (V-potential) This test mode directly measures the capacitance between the HV terminal and the housing (which is grounded). The partial capacitances that are undesirable for the measurement are connected to the V-potential point and thereby rendered ineffective.

  • Page 33: Interference Suppression

    The measurement will take a little bit longer when these algorithms are applied, please be patient and do not release the handheld before the measurement is complete. The progress bar during interference suppression measurement The Midas micro 2883 interference suppression makes accurate measurements possible even in adverse interfering environment. Functional Description...

  • Page 34: Operation Elements

    Operation Elements Front-Panel Features Ground Terminal / Earthing Ventilation Slots High Voltage Output Emergency Stop Button Low Voltage Point V Measuring Input HV GND Measuring Input A Measuring Input B Safety Switch Input External Warning Lamp Output Warning Lamp Temperature Sensor Input USB Port Ethernet Port Display with Touch panel...

  • Page 35: Ground Terminal

    7.1.1 Ground Terminal Wing nut ground terminal for connecting the safety ground lead to earth ground (connected to the instruments housing and the ground pin from the mains connector, there is no measuring or AC supply functionality) A separate green/yellow earthing cable is provided for the purpose of safety grounding the instrument. The Safety Ground cable should be connected to the Earthing Screw on the left side of the front panel of the Midas micro at one end and to the station grounding system at the other end.

  • Page 36: Safety Switch Input

    7.1.11 Warning Lamp The LED on the front panel indicates the actual high voltage state of the Midas micro 2883 (see chapter 4 Safety). High voltage output is short circuited  no danger from the device. The system is ready to start HV. Selecting HVon on the touchscreen will power up the HV source.

  • Page 37: External Temperature Sensor

    7.1.12 External Temperature Sensor Plug receptacle for connecting an external temperature probe (optional, see chapter 15 Accessories and Options). The sensor can be attached to the DUT magnetically. The temperature is measured in a 4-wire configuration. Pinout Signal Supply + Sense Wire + Sense Wire - Supply -...

  • Page 38: Power Switch

    7.1.19 Power Switch Switch to power up the device Always switch off the unit using the front power switch before connecting or removing the mains power cord. The mains input must be connected to a suitably rated power source. The protective earth connection of the mains input must be connected to an appropriate protective earth, otherwise there is a safety risk for the operator.

  • Page 39: User Interface

    User interface Startup Screen When starting up a warning screen is displayed to remind the user of the most important safety instructions. Read the warnings on the screen carefully and make sure you understand them. Confirm by clicking Ok. User interface...

  • Page 40: Homescreen

    Homescreen The Home Screen is the starting point for the Midas micro 2883 software. From here you can select all the different measurement modes as well as the Results and Setup Screens. The table below provides a short overview of the options.

  • Page 41: Basic Mode

    The basic mode screen can be seen above. A test begins with the definition of the parameters. When starting a measurement the Midas micro 2883 will source high voltage to the DUT with the values set in the test definition area.

  • Page 42: Status Bar

    Attempts to disconnect leads while the MIDAS micro 2883 is energized may result in a serious and possibly lethal electrical shock.

  • Page 43: Test Definition Area

    and power ground. Emergency pressed This warning indicates that the Emergency Stop Button has been pressed and needs to be released in order to turn on high voltage. Turn the Emergency Stop Button clock wise to release it. Overheated This warning indicates that the internal transformer’s temperature has risen above the security shutoff temperature.

  • Page 44: Measurement Bar And Displays

    Channel selection Select which channel(s) should be measured. The right part indicates how the measurement inputs are connected internally. Coloured symbols mean the input is connected to measurement. Greyed out V symbols mean the input is short-circuited to high voltage ground (guarded). 9.1.3 Measurement Bar and Displays The measurement bar shows the actual measurement displays.
  • Page 45 Interference . Basic Mode...

  • Page 46: Recorded Measurements

    9.1.6 Toolbar Controls The toolbar in Basic Mode The toolbar provides quick access to the most important features of the Midas micro 2883 basic mode. Start Button Starts the measurement with the parameters set in the test definition bar. When pressing this button high voltage will be turned on.
  • Page 47 Prints out the selected rows of the measurement data window. Note: the header on the print out is only printed the first time. Save File Saves a file containing all the data displayed in the measuring data window on a USB stick under a name selected by the user.

  • Page 48: Guided Mode

    In the first step select the type of DUT you want to perform the measurements on. Use the arrows to scroll through the options. If you cannot find the type of device you wish to test in the list, please contact support@tettex.ch. See chapter 20 Applications Guide to see more detailed description of the supported types of DUT.
  • Page 49 DUT are implemented. If you are missing a specific test please inform us at support@tettex.com. If you want complete freedom of test definition please use advanced mode. In the next step the test parameters are defined.
  • Page 50 Sometimes more than one parameter is selectable. On the image above you can select the test voltage, as well as the test frequencies. The dots in the Frequencies field show that more than one value has been selected. Click on the button to edit these values.

  • Page 51: Instruction Screen

    By entering a value in the top line using the on screen keyboard and then clicking on the Add button, a new test point will be added at the end of the list. You can clear the whole list by clicking on the Clear Button. Once all the desired measurement points are in the list, the selection can be confirmed by clicking on the Ok Button.

  • Page 52: Measurement Start Screen

    Connection schematic Connect the measuring cables and the HV supply cable as shown on the image. Do not forget to use proper grounding as the earthing cable is not shown in the schematic. Progress Shows the progress of the measurement. Skip Button With the skip button you can skip one of the steps.
  • Page 53 If maximum output current is sourced for a long period the internal HV source may heat up. In order to protect the device from damage the Midas micro 2883 comes with an overheat protection. Please wait until the HV source has cooled down and retry.

  • Page 54: The Measurement Screen

    10.4 The measurement screen During the measurement the screen looks like shown below. The screen is composed of the status bar, the test definition bar below, the measured values area and the tool bar. All these areas are described in the following chapters.

  • Page 55: Status Bar

    Attempts to disconnect leads while the MIDAS micro 2883 is energized may result in a serious and possibly lethal electrical shock.
  • Page 56 HV GND not connected The HV GND input is not connected to power ground. This check guarantees that there is always a low-resistance connection between high voltage ground and power ground. Emergency pressed This warning indicates that the Emergency Stop Button has been pressed and needs to be released in order to turn on high voltage.

  • Page 57: Measurement Bar And Displays

    10.4.2 Measurement Bar and Displays The measurement bar shows the actual measurement displays. The first display is always indicating the voltage on the high voltage output. The other three displays can be configured by the user. The values can be changed by clicking on the display.

  • Page 58: Special Symbols In Measurement Values

    10.4.4 Special Symbols in Measurement Values Symbol Explanation Stands for reduced voltage. Occurs when the desired voltage cannot be reached because of one of the following reasons: No Signal at Cx  The voltage is limited to 5 kV in order to prevent high voltages when cables are not connected correctly.

  • Page 59: The Results Screen

    From the final results screen you can no longer step backward or repeat steps. Use view data instead if you want to check measurement values before finalizing the measurement. View Data Leads to a the results screen with the actual measurements. The functionality is similar to the result screen, as described in chapter 13 Results Screen, except that the file menu is not available.

  • Page 60: Advanced Mode

    11 Advanced Mode The advanced mode gives the user all the options and freedom to measure manually or to create custom sequences to perform automated measurement. It addresses expert users with the need for complete freedom of choice for the parameterisation of their measurements. 11.1 Manual Tab The manual tab allows the user to perform simple manual measurements, similar to basic mode.
  • Page 61 Attempts to disconnect leads while the MIDAS micro 2883 is energized may result in a serious and possibly lethal electrical shock.

  • Page 62: Measurement Bar And Displays

    Emergency pressed This warning indicates that the Emergency Stop Button has been pressed and needs to be released in order to turn on high voltage. Turn the Emergency Stop Button clock wise to release it. Overheated This warning indicates that the internal transformer’s temperature has risen above the security shutoff temperature.

  • Page 63: Test Settings

    If small progress bars appear in the measurement display, this indicates that interference suppression is active. See chapter 6.4 Interference. 11.1.2 Test Settings Connection Settings Select the measuring mode (UST or GST) and the connection, you would like to measure. Test Definition Define Test voltage and frequency by entering the corresponding values in the text fields.

  • Page 64: Special Symbols In Measurement Values

    11.1.4 Special Symbols in Measurement Values Symbol Explanation Stands for reduced voltage. Occurs when the desired voltage cannot be reached because of one of the following reasons: No Signal at Cx  The voltage is limited to 5 kV in order to prevent high voltages when cables are not connected correctly.

  • Page 65: The Tools Menu

    11.1.6 The Tools Menu When clicking on the tools button, the tools menu appears: Below you can find a listing of all the options of the tools menu. Edit Comment Allows editing the text in the Comment column of the selected entry(s).
  • Page 66 Select Columns Dialog Available Columns Lists all the available measurement values. You can select values by clicking on the text. For an explanation of each measurement value see chapter 14 Measurement Values. Displayed Columns Lists the measurement values which are displayed in the measurement display area.

  • Page 67: The File Menu

    11.1.7 The File Menu The internal file system of the Midas micro 2883 is an XML structure. If a measuring data transfer to the USB stick is performed the data are always exported in two formats: XML and CSV. Due to clarity reasons only the XML files are visualized in the file list structures to keep the interface simple.

  • Page 68: Sequence Tab

    Copy Files to Allows copying files from the MIDAS micro 2883 to the external USB Drive (arrow to the right) or from the USB Drive to the instrument (arrow to the left). Select files either in the file list to the left (contents of 2883 storage) or to the right (contents of USB Drive) then click on the corresponding arrow button.
  • Page 69 Sequence window The table below shows the meaning of the column headers. Field Description Number of line or measurement in the sequence Descr. Description of the Measurement to perform. This text can be used to filter the measurements in the results screen. Voltage The test voltage for the measurement Frequency...

  • Page 70: The Tools Menu

    Example for a sequence: The sequence displayed above will perform the following measurements, in the following order: UST A @ 2kV, 50 Hz UST A @ 4kV, 50 Hz UST B @ 4kV, 50 Hz GST g(A+B) @ 6kV, 60Hz 11.2.2 The Tools Menu Advanced Mode...

  • Page 71: File Menu

    Edit Edits the currently selected cell. Add Row Adds a sequence step. The new step will be inserted after the currently selected line, copying its values. The new line can afterwards be edited. Delete Row Deletes the currently selected row(s) Voltage Steps Define a sub sequence of voltage steps.

  • Page 72: Sequence Tab During Measurement

    11.2.4 Sequence tab during measurement The sequence tab during measurement During measurement the sequence display area is split into two part: in the top the actual sequence step is shown and in the bottom the measurement results. A red indicator marks the sequence step currently measured. The results will be filled into the measurement display area while the sequence is running.

  • Page 73: Setup

    12 Setup The setup screen can be accessed from different modes. Dependant on that mode the setup tabs may vary. 12.1 DUT tab Not available in: Homescreen The DUT tab On the DUT tab the user can enter information about the device under test. Under Type the serial number and the type of the device can be entered.

  • Page 74: Miscellaneous Tab

    Here you can first select the type of device and the manufacturer in order to load the corresponding correction table. When a DUT temperature correction is selected, the measurement values “@ 20°C” will be calculated automatically using the corresponding correction table. 12.2 Miscellaneous Tab The miscellaneous tab The miscellaneous tab provides various settings and information about the soft- and hardware.
  • Page 75 Device Information Provides information about the device, such as Serial Number, Soft- and Hardware versioning and Calibration. Please provide this information when contacting Tettex Support. Load Factory Default All the settings will be reset to the factory defaults. Set Date & Time Set the Date and Time of the device.

  • Page 76: Settings Tab

    12.3 Settings Tab Some of the measurement settings not available in Basic Mode The Settings tab 12.3.1 Measurement settings HV Off after measurement Normally checked. Automatically turns off the high voltage in manual mode when a valid and stable measurement value has been recorded.

  • Page 77: Extended Gst Accuracy

    12.3.2 Extended GST accuracy The right side of this setup tab is dedicated to the Extended GST Accuracy settings. When measuring a grounded specimen all stray capacitances between high voltage and ground enter the measurement. Normally the influence of these stray capacitances is small. However, when measuring devices with small capacitance (<1nF), this may induce a considerable error to the measurement.
  • Page 78 The preparation screen informs about the current settings and the present warnings. Press HV On to start the measurement. During the measurement the top bar is blinking red to indicate that high voltage is on. The relevant measurement values are displayed. Please wait until a stable value has been determined. Setup...

  • Page 79: Extended Noise Reduction

    12.3.3 Extended Noise Reduction Firmware Version 1.1.0 and greater The MIDAS micro 2883 incorportates The Extended Noise Reduction The Midas micro uses special filter algorithms to reduce the noise and extract the measuring signal. See chapter 6.4 for more information.

  • Page 80: Preferences Tab

    12.4 Preferences Tab Only available on home screen and in advanced mode The preferred settings decide which values will be displayed by default in the measurement display. Normally after setting up the unit the last set values are used again after a restart in the setup respectively in the display. Select preferred values Select between tan δ...

  • Page 81: Limits Tab

    12.5 Limits Tab It is possible to define a tan delta limit as a pass/fail flag for the test, on this screen the Actual Limit and the default Limit can be defined. If the limits are enable a pass fail flag column will be added to the results after selected Actual limit is the value to be used on the actual test Default limit is the default limt defined when a new test is selected Limits are defined for a complete test, and should not be changed during the measurement.

  • Page 82: Limits In Guided Mode

    12.5.1 Limits in Guided mode To see the pass/Fail flag, select “Limit tanδ test” in one of the indicators. Then a Green “Pass” or a red “Fail square will be shown after a measuring point is finalized in the corresponding column Setup...

  • Page 83: Limits In Advance Mode

    12.5.1 Limits in Advance mode In advance mode, the limit values can be added as columns to the measurement, 2 columns can be added • Limit tan δ -> contains the actual value used for comparison • Limit tanδ test -> the pass/Fail Flag 12.5.1 Limits in Reports and Graph The limit used for evaluation is recorded for every measurement, and will be shown in the report and in the CSV file for each...

  • Page 84: Notes Tab

    The limits can also be selected for the Y axe in the Graphs, will be coded as 0 if passed, 1 in fail 12.6 Notes Tab Setup...

  • Page 85: Firmware Update

    The notes tab Use this page to make any notes you want to save inside the measurement file. 12.7 Firmware Update In order to provide the user with the latest features and bug fixes a firmware updater is implemented in the Midas micro software.
  • Page 86 Update File selection The firmware file name changed from Nano_1_x_x.tar to Micro_1_1_.tar Select the update file you want to install and click on the Update Button. Pop-up windows will inform you about the progress of the update. When finished, you will be informed of the successful completion of the update and prompted to restart the instrument.

  • Page 87: Results Screen

    13 Results Screen The results screen lets you analyze the actual and previous measurements (when saved). It is composed of two tabs. The table tab shows a listing of all the results. The graph tab shows a graph of selected measurements. The results screen is a powerful tool to analyze the measurement results onsite.

  • Page 88: The File Menu

    Opens the File Menu 13.1.1 The File Menu The internal file system of the Midas micro 2883 is an XML structure. If a measuring data transfer to the USB stick is performed the data are always exported in two formats: XML and CSV.
  • Page 89 File transfer dialog Copy Files to Allows copying files from the MIDAS micro 2883 to the external USB Drive (arrow to the right) or from the USB Drive to the instrument (arrow to the left). Select files either in the file list to the left (contents of 2883 storage) or to the right (contents of USB Drive) then click on the corresponding arrow button.

  • Page 90: Select Columns Dialog

    13.1.2 Select Columns Dialog The select columns dialog allows the user to select which measurement values will be displayed. The select columns dialog Available Columns Lists all the available measurement values. You can select values by clicking on the text. For an explanation of each measurement value see chapter 14 Measurement Values.

  • Page 91: The Graph Tab

    13.2 The Graph Tab 13.2.1 Filters With the following buttons you can filter the displayed values. When clicking on one of the filter buttons a list of available filter values will open up. You can select and deselect a filter by clicking on it. The selected filters will be displayed in green.

  • Page 92: The Graph

    13.2.2 The Graph The graph area with the y axis selector on the left side, the x axis selector at the bottom and the legend at the right side. The button on the left indicates the content of the y axis (here DF), the button on the bottom indicates the content of the x axis (here Frequency).

  • Page 93: Measurement Values

    14 Measurement Values 14.1 Description The measurement values as they can be selected in the Midas micro software Measurement Value Description DF (tan delta) The dissipation factor or tan delta of the DUT DF (tan delta) @ 20°C The dissipation factor or tan delta of the DUT with temperature correction DF (tan delta) % The dissipation factor or tan delta of the DUT in percentage notation for better readability.

  • Page 94: Data Format

    The logo used in the printout. This file is located in the root directory. Initially the Tettex Logo is stored here and will be used by default. This jpg. file can be replaced by your own one – just exchange the file.
  • Page 95 Address: 192.168.0.XX Address: 10.0.0.105 Address: 192.168.0.XX Address: 10.0.0.105 Subnet: 255.255.255.0 Subnet: 255.255.255.0 TCP-Port: TCP-Port: You can find the IP address configuration of your device in the “Setup” – “Miscellaneous” dialog: For connection, the following configuration in the Midas micro has to be defined DHCP ->...
  • Page 96 To connect to the midas micro FTP server, open a File Explorer window in Windows and type the following command ftp://192.168.0.XXX/ where XXX is the midas micro last part ip address A window asking for user and password will arise Introduce below user and password User ->...

  • Page 97: Accessories And Options

    15 Accessories and Options 15.1 Standard Accessories The MIDAS micro 2883 standard scope of supply includes a variety of accessories to perform various measurements. Optional accessories are also available. 15.1.1 High Voltage Cable There are two options of connectors that can be used for the high voltage cable. Included in the standard scope of supply is a clamp and as an option a hook is available.

  • Page 98: Extension Clamp

    The end of the high voltage cable is non insulated parts, including the black plastic and the bare metallic part of the clamp. Make sure that these parts are placed in safe distance from any ground potential (i.e. transformer tank or bushing flange). A flashover might occur.

  • Page 99: Bushing Adapters For Measurement Of C1

    15.1.3 Bushing Adapters for Measurement of C1 Connecting to a bushing tap using the adapter cable. The standard scope of supply includes two adapter cables (part number 4843453). They can be used to connect to bushings with a 4 mm test tap (i.e. Micafil type). Measured is the C1 of the bushing, see chapter 20.1 Bushings for more details. The adapter cable is connected on one side to the bushing test tap and on the other side to the BNC connector of the measurement cable.

  • Page 100: Bushing Adapter For Measurement Of C2

    15.1.5 Interlock adapter The interlock adapter (part number 0781631) is used if the MIDAS micro 2883 will be integrated in an interlock system (i.e. in a high voltage laboratory). See chapter 7.1.9 Safety Switch Input for information about the pinout.

  • Page 101: Cable Drums

    DUT setup in order to calculate the temperature compensation 15.2.5 Adapter LEMO to BNC Product number 2883/ALB Adapter cable for standard capacitors (Lemo3 – BNC). Can be used with Tettex type capacitors having LEMO sockets. i.e.: 3370 NK Accessories and Options...

  • Page 102: Hook For Hv Cable

    15.2.6 Hook for HV Cable Product number 2883/HOOK Hook for high voltage connection. Can be used instead of the clamp included in the Midas micro 2883 accessory bag. 15.2.7 Set of Hot Collar Tests Product number 2883/HCB Set of flexible bands for hot collar tests (see Subchapter Hot Collar Test in Chapter 20.1.2 Installed Bushings) or for guarding of leakage...

  • Page 103: Miscellaneous

    16.2 Care and Maintenance The Midas micro 2883 is basically service free, as long as the specified environmental conditions are adhered to. As a result, service and maintenance is restricted to cleaning of the equipment and calibration at intervals stipulated by the application for which the instrument is used.

  • Page 104: Packing And Transport

    16.3 Packing and Transport The packing of the MIDAS micro 2883 Measuring instrument provides satisfactory protection for normal transport conditions. Nevertheless, care should be taken when transporting the instrument. If return of the instrument is necessary, and the original packing crate is no longer available, then packing of an equivalent standard or better should be used.

  • Page 105: Trouble Shooting

    17 Trouble Shooting Problem Solution No high voltage at output Check for short circuit between high voltage and ground. Disconnect HV cable from DUT put it The high voltage does not rise when a somewhere safe and isolated and start HV at 500V. measurement is started.
  • Page 106 It should however be avoided to switch on the power source. Please contact support@tettex.com. Communication to Amplifier failed The communication protocol with the amplifier got stuck.

  • Page 107: Customer Support

    Customer Support Department of HAEFELY Hipotronics or your local agent. The Customer Support Department can be reached at the following address: HAEFELY HIPOTRONICS Customer Service - Tettex Birsstrasse 300 CH-4052 Basel Switzerland Tel:...

  • Page 108: Conformity

    19 Conformity Conformity...

  • Page 109: Applications Guide

    20 Applications Guide This chapter contains important information regarding construction of the test circuit and the individual test modes depending on the device under test. Selected circuits for specific test objects are presented for further information. Unfortunately it is not possible to provide a test circuit for every customer specific test object as this would exceed the capacity of this manual.
  • Page 110 In principle a condenser bushing is a series of concentric capacitors between the center conductor and ground sleeve or mounting flange. A conducting layer near the ground sleeve may be tapped and brought out to a tap terminal to provide a three-terminal specimen.

  • Page 111: Spare Bushings

    20.1.1 Spare Bushings For testing a spare bushing care must be taken in the method used to hoist the bushing. The bushing should be mounted in a grounded metal rack with nothing connected to the terminals. Tests should not be performed with the bushings mounted in wooden crates or lying on a floor. Otherwise the test results can be affected by the wood or the cement floor.

  • Page 112: Installed Bushings

    20.1.2 Installed Bushings Overall Test (Centre Conductor to Flange) If a bushing is mounted on an equipment, the overall measurement method would include all conduction and insulation elements connected between the bushing center conductor and ground. Therefore the overall method is not recommended for separate tests on bushings, unless the bushing conductor can be completely isolated or the bushing has no tap.
  • Page 113 In analogy to the tap insulation test on spare bushings the C2 insulation is measured by the GST gA+B mode. The connection is shown beside. For the capacitance C2 (tap to flange) the dissipation factor is calculated but normally not corrected for temperature.

  • Page 114: Measuring Data Interpretation

    20.1.3 Measuring Data Interpretation Condenser Bushings The dissipation factor and capacitance recorded are compared with one or more of the following: • Nameplate data. • Results of prior tests on the same bushing. • Results of similar tests on similar bushings. Dissipation factors for modern condenser bushings are generally in the order of 0.5% after correction to 20°C.
  • Page 115 Power and distribution transformers exist as single-phase or three-phase design. For insulation purposes transformers can be further classified as dry type which have air or gas as insulation and cooling medium, or as ® liquid-filled constructions which have mineral oil, Askarel or other synthetic materials.
  • Page 116 Two Winding Transformers (3 phase and single-phase) Measurement connections of a two windings transformer for measurement of C and C Test Connections Sequen INPUT A INPUT Test Mode High Voltage ce Line HV GND Tank GND UST A Tank GND GST gA+B Tank GND GST gA+B...
  • Page 117 Autotransformers (3 phase and single-phase) Contrary to the two-winding transformer the windings of an autotransformer cannot be separated. The winding of an autotransformer is a combination of the high- and low-voltage windings (HV and LV, see figure below). For testing the insulation of an autotransformer all seven bushings (three bushings for a single-phase unit) have to be connected together (HV1+HV2+HV3+LV1+LV2+LV3+0).
  • Page 118 of the sandwiched winding is to effectively eliminate the interwinding capacitance except for stray capacitances between bushing leads. 3 phase, 3 winding transformer in Yn-Yn formation with tertiary winding. Measurement connections for measurement of C and C Test Connections Sequen INPUT A INPUT B INPUT...
  • Page 119 Abnormal power factors are occasionally recorded for inter-winding insulations of two-winding transformers. These may be the result of improper (high-resistance) grounding of the transformer tank, or the use of grounded electrostatic shielding between transformer windings. In this case, as a result of the ground shield, the inter-winding capacitance is practically non-existent except for stray capacitances between bushing leads.

  • Page 120: Shunt Reactors

    20.2.2 Shunt Reactors Oil-filled shunt reactors are used in HV systems to limit over-voltage surges associated with long transmission lines. The shunt reactor compensates the capacitive generation on power lines to avoid non-controlled voltage rise especially on lightly loaded lines. Two configurations of shunt reactors are available: either each phase is contained in its own separate tank or all three phases are contained in a common tank.

  • Page 121: Current Transformers

    20.2.3 Current Transformers Current transformers (CTs) convert high transmission line current to a lower, standardized value to be handled by instrumentation. The measures are used for network control, protection and revenue metering. Current transformers have voltage ratings from several kilovolts up to the highest system voltages now in operation.
  • Page 122 A test procedure with the corresponding test modes is shown in the figure below. The connection between the intermediate voltage of the voltage divider and the tuning reactor must be opened. Then the capacitance and the loss factor of the capacitor voltage divider can be measured as outlined in the table below. Since the high voltage winding of the transformer is not capacitive graded, a measurement of the loss angle (tan δ) will give no significant results.

  • Page 123: Excitation Current Measurement

    20.2.5 Excitation Current Measurement The excitation current measurement can be used to detect short-circuited turns, poor electrical connections, core de-laminations, core lamination shorts, tap changer problems and other possible windings and core problems in the transformer. In principle the test measures the current needed to magnetize the core and generate the magnetic field in the windings.
  • Page 124 Excitation Current Measurement on a Y-y or Y-yn transformer Excitation current measurement connection for L measurement on a Y-y or Y-yn transformer Test Connections DUT, High Voltage INPUT A INPUT B HV GND INPUT Test Mode excitation current through Tank GND UST A H1 + Tank GND...

  • Page 125: Liquid Insulation

    Test Connections DUT, High Voltage INPUT A INPUT B HV GND INPUT Test Mode excitation current through Tank GND UST A Tank GND UST B Tank GND UST A Measuring Data Interpretation On a three-phase, star/delta or delta/star transformer, the excitation current pattern will generally be higher on two phases than on the remaining phase.

  • Page 126: Measuring Data Interpretation

    special connection cables. A clearance of several centimeters should be maintained between the HV connection and the ring which is connected to V-potential, so that flashover will not occur between these parts. The test voltage should be raised to 10 kV. The radial electrode spacing of the cell is about 6.7 mm, the sample should not break down at this voltage unless it is in very poor condition.

  • Page 127: Cables

    moisture. The necessity for further tests will depend to a large extent upon the magnitude of the dissipation factor, the importance of the apparatus in which the insulation liquid was used, its rating, and the quantity of insulation liquid involved. 20.4 Cables Dissipation-factor tests on cables are useful to indicate general deterioration and/or contamination.

  • Page 128: Test Procedure Example

    20.4.2 Test Procedure Example The figure and table below shows the specific connections with the corresponding test modes of a typical belted three-phase cable. It is assumed that no phase is left floating. 3 Phase Unshielded Cables Enclosed in a Common Metallic Sheath: Test connections to measure C Test Connections INPUT A INPUT B...

  • Page 129: Capacitors

    20.5 Capacitors Capacitor test do check the insulation quality of the device. Normally the dissipation factor should be low and should stay stable as well as the capacitance. Units to be tested are power-factor correction capacitors (cap banks, used to improve the power factor of a high voltage grid), surge capacitors, energy storage capacitors, etc. Capacitors can be built based on series of single cap modules (e.g.
  • Page 130 As the internal AC power source of the MIDAS micro 2883 system can supply maximum 12kV, the insulation tests of breakers rated above 23.6kV are performed at 12kV. Depending on the nominal line voltage, operating mechanism (spring, hydraulic) and arc-quenching medium (air, oil, sulphur hexafluoride) circuit breakers are sometimes designed with two or more series connected interrupting chambers.

  • Page 131: Dead Tank Breaker

    20.6.1 Dead Tank Breaker The test connections for a Dead Tank Breaker (e.g. ABB PASS type) is outlined below: Dead Tank Breaker measurement connections for measurement of C and C contact insulation capacitance earth insulation capacitance Test Connections INPUT A INPUT Test Mode High Voltage...

  • Page 132: Live Tank Breaker

    20.6.2 Live Tank Breaker The test procedure for a Live Tank Breaker (e.g. SIEMENS 3AP1 type) is shown below: Live Tank Breaker measurement connections + (PS bushing stray capacitances (undrawn) grading capacitors + (PS insulation column capacitance breaker switches , PS pre insertion switches pre insertion resistors Test Connections...

  • Page 133: Measuring Data Interpretation

    Experience has demonstrated that the measurement of power loss is an effective method of evaluating the integrity of an arrester. On the MIDAS micro 2883 power losses are automatically calculated and can be displayed by selecting the corresponding value “Real Power P”.

  • Page 134: Test Procedures

    20.7.1 Test Levels Surge arresters are built on a semiconductor or a metal oxide which have a non-linear volt-ampere characteristic. In order to permit meaningful comparisons between different units or older measurement results the test on surge arresters should always be performed at the same test voltage. The following table gives an overview of recommended Test Levels for several surge arresters.
  • Page 135 Test High INPUT INPUT Mode Voltage HV GND UST A GST gA+B Double unit arrester stack measurement, connection for measurement of S1. Test Procedure on a Multi-Unit Arrester Stack Assemblies consisting of three units or more per phase are tested in the manner outlined in figure 53 on the next page.
  • Page 136 • Mistake in assembly. • Poor contact and open circuits between elements Applications Guide...