ENGLISH User manual Copyright HT ITALIA 2007 Release EN 1.
M71 Table of contents: 1. 2. 3. 4. SAFETY PRECAUTIONS AND PROCEDURES ......................................................... 2 1.1. 1.2. 1.3. 1.4. Preliminary instructions ..................................................................................................... 3 During use ........................................................................................................................ 3 After use ....................................................................................
M71 1. SAFETY PRECAUTIONS AND PROCEDURES This instrument was designed in compliance with the IEC/EN61557-1 and IEC/EN61010-1 guidelines relative to electronic equipment. CAUTION For your own safety and to avoid damaging the instrument you are recommended to follow the procedures described in this manual and read carefully all instructions preceded by this symbol .
M71 1.1.
M71 1.4. DEFINITION OF MEASUREMENT CATEGORY (OVERVOLTAGE) Standards IEC/EN61010-1 (Safety requirements for electrical equipment for measurement, control and laboratory use, Part 1: General requirements) define what a measurement category (usually called “overvoltage category”) is. At § 6.7.4: Measuring circuits it quotes: Circuits are divided into the following measurement categories: • Measurement category IV is for measurements performed at the source of a lowvoltage installation.
M71 2. GENERAL DESCRIPTION This instrument, whether used according to the instructions given in this manual, will grant you accurate and reliable measurements. Thanks to a development of newest conception assuring double insulation and overvoltage category III you will enjoy the highest safety. The instrument is capable of performing the following measurements: EARTH 2W: Two-wire earth resistance measurement . EARTH 3W: Three-wire earth resistance measurement. 3. PREPARING THE INSTRUMENT 3.1.
M71 4. WORKING INSTRUCTIONS 4.1. INSTRUMENT DESCRIPTION CAPTION: 1. 2. 3. 4. 5. 6. 7. Inputs Display ON/OFF key CAL key Switch of test mode AUTO key GO key Fig. 1: Instrument's front panel Key to switch on and off the instrument. CAL CAL key to effect zero setting of cables under modes EARTH-2W e EARTH3W. AUTO AUTO key to start/stop the mode detecting critical measuring conditions (high electric noise) with automatic updating of measuring time. GO GO key to start measurement.
M71 4.1.1. Switching on When switching on the instrument a brief tone is audible along with display of all segments for about one second. Subsequently the last firmware version as well as the last selected measuring mode are displayed before switching off. 4.1.2. Auto Power OFF To save battery life the instrument automatically turns off 5 minutes after last pressure of keys. To resume operation turn on the instrument pressing the start key. 4.2.
M71 4.3. EARTH 2W:TWO-WIRE EARTH RESISTANCE MEASUREMENT 4.3.1. EARTH 2W- Zero setting of cables CAUTION The instrument can be used for voltage and current measurements on installations with overvoltage category equal to CAT III 240V to earth and maximum voltage of 415V between inputs. Do not connect the instrument to installations whose voltages exceed the limits indicated in this manual. Exceeding such limits may cause electric shock to the user and damage the instrument.
M71 6. CAL After pressing the CAL key the instrument carries out zero setting of cables' resistance (this procedure takes approx. 30sec). Cables with a resistance up to 2Ω can be calibrated. CAUTION When “Measuring…” is displayed the instrument is effecting measurement. During this phase do not disconnect test leads from the instrument. 7.
M71 4.3.2. EARTH 2W- Measurement procedure CAUTION The instrument can be used for voltage and current measurements on installations with overvoltage category equal to CAT III 240V to earth and maximum voltage of 415V between inputs. Do not connect the instrument to installations whose voltages exceed the limits indicated in this manual. Exceeding such limits may cause electric shock to the user and damage the instrument. Fig. 3: Example of instrument's wiring for two-wire earth measurement Fig.
M71 ¾ Only in case of a TT system a neutral conductor can be used as auxiliary earth rod (see Fig. 4). CAUTION The instrument displays the sum value of RA +RT as result.
M71 4.3.3. Message description for EARTH 2W measurement 1. If the following condition is met: RDISPLAYED < 0.11Ω the instrument displays the symbol indicating that the reading may be affected by a relative error higher than 30%. 2. If the following condition is met: Disruptive voltage > 3.0V the instrument displays the symbol indicating that the reading is carried out under critical conditions. 3. If the following condition is met: RMEASURED - RCABLES < - 0.
M71 4.4. EARTH 3W: THREE WIRE EARTH RESISTANCE MEASUREMENT 4.4.1. EARTH 3W- Zero setting of cables CAUTION The instrument can be used for voltage and current measurements on installations with overvoltage category equal to CAT III 240V to earth and maximum voltage of 415V between inputs. Do not connect the instrument to installations whose voltages exceed the limits indicated in this manual. Exceeding such limits may cause electric shock to the user and damage the instrument.
M71 6. CAL After pressing the CAL key the instrument carries out zero setting of cables' resistance (this procedure takes approx. 30sec). Cables with a resistance up to 0.3Ω can be calibrated. CAUTION When “Measuring…” is displayed the instrument is effecting measurement. During this phase do not disconnect test leads from the instrument. 7.
M71 4.4.2. EARTH 3W- Measurement procedure CAUTION The instrument can be used for voltage and current measurements on installations with overvoltage category equal to CAT III 240V to earth and maximum voltage of 415V between inputs. Do not connect the instrument to installations whose voltages exceed the limits indicated in this manual. Exceeding such limits may cause electric shock to the user and damage the instrument. Fig.
M71 1. Press the instrument's start key. 2. Select function EARTH 3W pressing the right arrow key. 3. 4. AUTO If the circuit under test is assumed to be affected by electric noise press the AUTO key to select the corresponding mode. Connect the red cable and the green cable into the corresponding instrument's input terminals. 5. Connect the crocodiles to the test leads. 6. When necessary (symbol CAL missing or use of a new set of cables) carry out zero setting of cable resistance (see § 4.4.1) 7.
M71 4.4.3. Message description for EARTH 3W measurement 1. If the following condition is met: RDISPLAYED < 0.11Ω the instrument displays the symbol indicating that the reading may be affected by a relative error higher than 30%. 2. If the following condition is met: Disruptive voltage > 3.0V the instrument displays the symbol indicating that the reading is carried out under critical conditions. 3. If the following condition is met: RMEASURED - RCABLES < - 0.
M71 6. If the volt metric circuit (terminal S) shows a too high resistance value the side message is displayed. Check connection of red and green wires as well as their integrity. If the problem still exists connect two or more auxiliary rods in parallel and pour some water around the rods in order to make a better volt metric probe (that is the ground rod connected to the red wire). 7. If the ampere metric circuit (terminal H) shows a too high resistance value the side message is displayed.
M71 5. MAINTENANCE 5.1. GENERAL 1. This instrument is a precision meter. During its use and storage you are recommended to keep the instructions listed in this manual to avoid any harm or danger 2. Do not use the instrument in excessively wet environments and under high temperatures. Do not expose it to direct sunlight 3. Always switch the instrument off after use.
M71 6. TECHNICAL SPECIFICATIONS 6.1. TECHNICAL FEATURES Accuracy is indicated as [% rdg + (dgt number) * resolution] at 23°C ± 5°C,< 80%HR CAUTION Under modes EARTH-2W and EARTH-3W the instrument displays the symbol of warning whenever: • It is working under critical conditions, such as in the presence of input voltages • It cannot grant the uncertainty of measurement lower than 30% of reading, according to IEC/EN61557-1 Earth Resistance measurement Range Resolution 0.01 ÷ 19.99Ω 20.0 ÷ 199.
M71 6.1.1. Safety standards Instrument safety: Technical literature: Accessory safety: Insulation: Pollution degree: Maximum height: Overvoltage category: IEC/EN61010-1, IEC/EN61557-1, IEC/EN61557-5 IEC/EN61187 IEC/EN61010-031, IEC/EN61010-2-032 double insulation 2 2000m (6561ft) CAT III 240V to earth, maximum 415V between inputs 6.1.2.
M71 7. SERVICE 7.1. WARRANTY TERMS This instrument is guaranteed against material and manufacturing defects, in compliance with our general sales terms. During the warranty period all defective parts may be replaced, but the manufacturer reserves the right to decide either to repair or replace the product. Should you need to return the instrument back for repair or replacement take prior agreements with your dealer as transport expenses must be borne by the customer.
M71 8. PRACTICAL REPORTS FOR ELECTRICAL TESTS 8.1. EARTH RESISTANCE MEASUREMENT IN TT SYSTEMS PURPOSE OF THE TEST Make sure that the RCD is coordinated with the earth resistance value. It is not possible to take an earth resistance value as reference limit when controlling the measurement result, while it is always necessary to check that the coordination complies with the standards' requirements. INSTALLATIOIN PARTS TO BE CHECKED The earth installation under working conditions.
M71 8.2. EARTH RESISTANCE MEASUREMENT, VOLT AMPERE METRIC METHOD Method for small sized earth rods Let current stream between the earth rod and a current probe placed at a distance equal to fivefold the diagonal of the area limiting the earth installation. Place the voltage probe at approximately half way between the earth rod and the current probe, finally measure voltage between both of them.
M71 Method for medium and large sized earth rods This procedure is based on the volt ampere metric method as well, however it is mainly used whenever it is difficult to place an auxiliary current rod at a distance equal to fivefold the diagonal of the area limiting the earth installation. Place the current probe at a distance equal to the diagonal of the earth installation.
