METREL TeraOhm User Manual
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METREL TeraOhm User Manual

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TeraOhm 5 kV
MI 2077
User Manual
Version 1.4, Code No. 20 750 722

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Summary of Contents for METREL TeraOhm

  • Page 1 TeraOhm 5 kV MI 2077 User Manual Version 1.4, Code No. 20 750 722...
  • Page 2 TeraOhm 5kV Distributor: Producer: METREL d.d. Horjul 188 1354 Horjul Slovenia © 2002 Metrel No part of this publication may be reproduced or utilized in any form or by any means without permission in writing from METREL.

  • Page 3: Table Of Contents

    TeraOhm 5kV Table of contents 1. General introduction--------------------------------------------------------------------------- 4 1.1. Features ----------------------------------------------------------------------------------------4 1.2. Applied Standards----------------------------------------------------------------------------4 2. Instrument Description ----------------------------------------------------------------------- 5 2.1. Instrument Casing----------------------------------------------------------------------------5 2.2. Operator’s Panel------------------------------------------------------------------------------5 2.3. Connectors-------------------------------------------------------------------------------------6 2.4. Bottom Section--------------------------------------------------------------------------------7 2.5. Accessories ------------------------------------------------------------------------------------7 3. Warnings------------------------------------------------------------------------------------------- 8 4. Performing measurements ------------------------------------------------------------------ 10 4.

  • Page 4: General Introduction

    TeraOhm 5kV 1. General introduction 1.1. Features The TeraOhm 5kV Tester is a portable battery / mains powered test instrument intended for testing of Insulation Resistance by using high test voltages of up to 5 kV. It operates on a S and CLEAR basis.

  • Page 5: Instrument Description

    TeraOhm 5kV 2. Instrument Description 2.1. Instrument Casing The instrument is housed in a plastic casing that maintains the protection class defined in the general specifications. The casing is equipped with a carrying strap, which is intended for the instrument to be used hung around the operator’s neck. Short technical specification is available on base of the housing.

  • Page 6: Connectors

    TeraOhm 5kV 2.3. Connectors The TeraOhm 5 kV Tester contains the following connections: Connection of test leads to three banana safety sockets (1, 2, 3), Connection of the communication cable to the 9-pin RS 232 connector (4) and Mains supply cable connection to the mains socket (5).

  • Page 7: Bottom Section

    6 ..Screw (unscrew to replace the batteries). 7 ..Rubber foot. 2.5. Accessories The accessories consist of standard and optional accessories. Optional accessories can be delivered upon request. See attached list for standard configuration and options or contact your distributor or see the METREL home page: http://www.metrel.si...

  • Page 8: Warnings

    In order to reach the highest level of operator’s safety while carrying out various measurements and tests using the TeraOhm 5kV Tester, as well as to ensure that the test equipment remains undamaged, it is necessary to consider the following warnings: MEANING OF SYMBOLS ♦...
  • Page 9 TeraOhm 5kV • In case of a capacitive test object (long tested cable etc.), automatic discharge of the object may not be done immediately after finishing the measurement – “Please wait, discharging” message will be displayed. HANDLING WITH CAPACITIVE LOADS ♦...

  • Page 10: Performing Measurements

    TeraOhm 5kV 4. Performing measurements 4. 1. Switching on the instrument Autocalibration The instrument is switched ON by pressing the ON/OFF key. After turning instrument first executes the autocalibration (Fig. 5). It is necessary that the measuring test leads are disconnected during autocalibration. If not the instrument will require disconnection of the test leads and repeat switching OFF and ON.

  • Page 11: Configuration

    TeraOhm 5kV Off function The instrument can be switched OFF only by pressing the ON/OFF key. The auto-off function is not available due to the possible long-term measurements. 4.2. Configuration The configuration function enables the selection and adjustment of the parameters that are not directly involved in the measurement procedure (Figure 6).

  • Page 12: Measurements

    TeraOhm 5kV 5. Measurements 5.1. Generally about DC High voltage testing (FURTHER INFORMATION FOUND METREL’S HANDBOOK “INSULATION MEASURING TECHNIQUES”) The purpose of insulation tests Insulating materials are important parts of almost every electrical product. The material’s properties depend not only on its compound characteristics but also on temperature, pollution, moisture, ageing, electrical and mechanical stress, etc.
  • Page 13 RISO = surface leakage current RISS Some application examples for using Teraohm 5 kV Basic Insulation resistance test Virtually every standard concerning the safety of electrical equipment and installations requires the performance of a basic insulation testing. When testing lower values (in the Ω...
  • Page 14 In general, insulators that are in good condition will show a “high” polarization index while insulators that are damaged will not. Note that this rule is not always valid. Refer to Metrel’s handbook Insulation Testing Techniques for more information. General applicable values:...

  • Page 15: Guard Terminal

    TeraOhm 5kV Withstanding voltage test Some standards allow the use of a DC voltage as an alternative to AC withstanding voltage testing. For this purpose the test voltage has to be present across the insulation under test for a specific time. The test result passes if there is no breakdown or flash over.

  • Page 16: Filter Option

    TeraOhm 5kV DIAGNOSTIC STEP 4..8 TEST VOLTAGE + (Red) INSULATION WITHSTANDING RESISTANCE VOLTAGE SELECT LIGHT VOLTAGE CONFIG Guard START ON/OF TeraOhm 5kV - (Black) Fig. 7. Connection of GUARD terminal to measured object (an example for measuring cable insulation is shown) where: Ut ..Test voltage...
  • Page 17 TeraOhm 5kV Filter option Meaning Low pass filter with cut off frequency of 0.5 Hz in signal line. Fil1 Additional low pass filter with cut off frequency of 0.05 Hz in signal line. Fil2 Fil1 with increased integrating time (4 s).

  • Page 18: Voltage Measurement

    TeraOhm 5kV 5.4. Voltage measurement Selecting this function displays the following states (initial state and state with results after completion of the measurement). Initial display Display with results Fig. 8. Voltage function display states Measurement procedure: Connect the test leads to the instrument and to the measured source.
  • Page 19 TeraOhm 5kV Measurement procedure: Connect the test leads to the instrument and to the tested object. Select INSULATION RESISTANCE function using the rotary switch knob. Press the START key and release it, continuous measurement starts to run. Wait until the test result has stabilized then press the START key again to stop the measurement or until set timer runs out (if enabled).

  • Page 20: Diagnostic Test

    TeraOhm 5kV Legend of displayed symbols: Name of selected function INSULATION RESISTANCE SETTING PARAMETERS: Set test voltage – step 50 V 1000V Unominal Duration of measurement Timer 10min 00s ON: timer enabled, OFF: timer disabled Timer on/off Time to accept and display first Rmin and...
  • Page 21 TeraOhm 5kV µ where: t ...period of first time unit (e.g. 1min) U ..test voltage. DIELECTRIC DISCHARGE TESTING (DD) DD is the diagnostic insulation test carried out after the completion of the Insulation Resistance measurement. Typically the insulation material is left connected to the test ÷...
  • Page 22 TeraOhm 5kV Notes: A high-voltage warning symbol appears on the display during the measurement to warn the operator of a possible dangerous test voltage. The value of capacitance is measured during the final discharge of the measured object. If enabled, the instrument measures DD when the measured capacitance is in the µ...

  • Page 23: Step Voltage Insulation Resistance Testing

    TeraOhm 5kV 5.7. Step Voltage Insulation Resistance testing Selecting this function displays the following states (initial state and state with results after the completion of the measurement). Initial display Display with results Fig. 14. Step Voltage Insulation Resistance function display states Insulation is measured in five equal time periods at test voltages from one fifth up to full scale, see the figure 15.
  • Page 24 TeraOhm 5kV Legend of displayed symbols: Name of selected function STEP VOLTAGE Filter type enabled, see the chapter 5.3. Off (Fil1, Fil2, Fil3) Configuration Set test voltage – step 250 V 1500V Actual test voltage – measured value U=1593V Actual test current – measured value I=0.00nA...

  • Page 25: Withstanding Voltage

    TeraOhm 5kV Note: Maximum value for Step Time is 30 min. Warning! • Refer to Warnings chapter for safety precautions! 5.8. Withstanding voltage This function offers Withstanding Voltage test of insulation material. It covers two types of tests: a) Breakdown voltage testing of high voltage device, e.g. transient suppressors and b) DC withstanding voltage test for insulation coordination purposes.
  • Page 26 TeraOhm 5kV Initial display Display with results Fig. 18. Withstanding Voltage function display states Measuring procedure: Connect the test leads to the instrument and to the measured object. Press the START key to start the measurement. Wait until the set timers run out or until breakdown occurs, the result is displayed.
  • Page 27 TeraOhm 5kV Set-up parameters for Withstanding Voltage: Press the SELECT key, Set-up menu appears on display, see the figure 19. ↑ ↑ ↑ ↑ ↓ ↓ ↓ ↓ Select parameter (line) to be set using the keys; ← ← ← ←...

  • Page 28: Operation With Results

    TeraOhm 5kV 6. Operation with Results 6.1. Store, Recall and Clear Operation The instrument contains battery backup storage to retain the stored results. This is to enables the user first to make the measurements and later to recall them, analyze and print results or transfer them to a computer for further analysis.
  • Page 29 TeraOhm 5kV Function List of stored data Voltage Function name Measured voltage Frequency of measured voltage Ser. number of stored result Date * Time * Insulation resistance Function name Measured insulation resistance value Set test voltage Actual test voltage - measured value...

  • Page 30: Data Transfer

    TeraOhm 5kV Step voltage Function name Last measured insulation resistance Set test voltage Actual test voltage - measured value Actual test current - measured value Capacitance of tested object Complete duration of measurement First step measured resistance with its nominal voltage...

  • Page 31: Maintenance

    TeraOhm 5kV 7. Maintenance 7.1. Inspection To maintain the operator’s safety and to ensure the reliability of the instrument it is advisable to inspect the instrument on a regular basis. Check that the instrument and its accessories are not damaged. If any defect is found please consult your service center, distributor or manufacturer.

  • Page 32: Cleaning

    TeraOhm 5kV Fig. 21. Correct polarity of inserted batteries Notes! • Insert cells correctly, otherwise test instrument will not operate and battery may be discharged! • If the instrument is not to be used for a long period of time remove all batteries from battery compartment.

  • Page 33: Specifications

    TeraOhm 5kV 8. Specifications 8.1. Measurements Insulation resistance Nominal test voltage: Any within 250 and 5000 V Current capability of test generator: >1 m A Short-circuit test current: 1.4 m A max. Automatic discharge of tested object: Ω Ω Measuring range Riso: 0.12 M...
  • Page 34 TeraOhm 5kV Generator Capability vs. Resistance Output voltage [kV] Ω Resistance under test (M ) * Note: examples of selected output voltage Withstanding voltage Voltage DC Display range Withstanding voltage (V) Resolution Accuracy ÷ ± 5500 (3 % of reading + 40 V)

  • Page 35: General Specifications

    TeraOhm 5kV Capacitance µ Measuring range C: 50 Display range C Resolution Accuracy ÷ 0.1 nF 99.9 nF ± ÷ (5 % of reading + 2 digits) 1 nF 999 nF ÷ µ 10 nF *Full-scale value of capacitance is defined according to the following equation: µ...
  • Page 36 TeraOhm 5kV DISCHARGING Every time after measurement completion. Ω ± Discharging resistance:........100 k 10 % SERIAL COMMUNICATION RS232 serial communication ......galvanic separated Baud rates:.............2400, 4800, 9600, 19200 baud, 1 stop bit, no parity. Connector: .............standard RS232 9-pin D female. CLOCK Built-in Real time clock........Displayed permanently and stored as a...

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