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Summary of Contents for Megger DLRO 200
- Page 1 DLRO ® High Current, Low Resistance Ohmmeter Megger DLRO200 Digital Low Resistance Micro Ohmmeter USER MANUAL www.actoolsupply.com...
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Page 2: Safety Warnings
www.actoolsupply.com SAFETY WARNINGS THESE SAFETY WARNINGS MUST BE READ AND UNDERSTOOD BEFORE THE INSTRUMENT IS USED. DLRO200 is supplied without a plug terminating the supply lead. An appropriate plug must be fitted prior to use. The DLRO200 must be grounded (earthed) when in use. If the ground / earth in the socket outlet being used to energise the DLRO200 cannot be relied upon, the instrument must be connected to a reliable earth / ground via the large green and yellow terminal on the left hand side of the instrument. If no ground / earth is present the instrument will refuse to switch on and the display will remain blank. Circuits must be de-energised before testing. The DLRO200 must only be used on dead systems. If the item under test has a voltage upon it greater than 10 volts ac peak or dc with reference to ground the DLRO200 will indicate the presence of the voltage and prevent any tests being carried out. -
Page 3: Table Of Contents
www.actoolsupply.com CONTENTS SAFETY WARNINGS GENERAL DESCRIPTION OPERATION Main Menu Screen TEST Menu OPTIONS Menu CURRENT Menu Warning Messages Entering Notes In The Memo Screen Test Result Storage Real Time downloading of test data. SYMBOLS USED IN THIS DOCUMENT AND ON THE INSTRUMENT TEST TECHNIQUES & APPLICATIONS u Protective Conductor Terminal Test Sequence Lead Resistance Hot Terminals Interference And Grounding The Sample Refer to the User Manual for more information SPECIFICATIONS Power On Power Off Equipment complies with relevant EU Directives www.actoolsupply.com... -
Page 4: General Description
GENERAL DESCRIPTION The Megger ® DLRO ® 200 is an a.c. powered low resistance ohmmeter voltage are clearly presented on the display after the test is complete. deigned to measure d.c. resistances in the low milliohms or microhms using a maximum test current of 200 Amps d.c. The maximum test current The use of a four terminal measurement technique removes the test lead available is dependent upon the power supply, the resistance of the test resistance from the measured value although the use of lightweight current leads and the resistance of the item being tested. Full details are available leads may prevent the DLRO200 from producing the full requested current. in the SPECIFICATIONS section later in this book. In this case the instrument will produce the highest current possible taking into account the resistance of the current leads and the item being tested. The power lead entry is located on the left-hand side panel and marked “100-265 V a.c., 10 A max., 50/60Hz” for the DLRO200, or ‘115 V a.c. Before a test may be started the potential test lead contact is monitored 10 A max. 50/60Hz’ for the DLRO200-115. The main On/Off switch is to ensure good contact is present. This reduces the chance of erroneous located next to the power lead entry. All other controls are mounted on readings and prevents arcing at the contact point, which would otherwise the front panel. Should the supply earth be inadequate the instrument damage the item under test and the test lead contacts. A resistance will refuse to switch on, the display will remain blank. An additional earth measurement takes approximately 10 seconds. terminal is provided on the left ahd side of the instrument. DLRO200 is supplied complete with a pair of 5 metre (16 feet) current leads terminated with large clamps, and smaller, lighter potential leads. Other lengths and terminations are available if required. The large terminals C1 and C2 supply a low voltage (from zero to 5 volts) which is adjusted automatically to produce the desired current (from 10 A to 200 A). C1 is the positive terminal. This d.c. voltage is half wave rectified and unsmoothed in the DLRO200, the inductance of the test leads providing sufficient smoothing for the current. The DLRO200-115 has additional smoothing within the instrument. -
Page 5: Operation
Plug the instrument supply lead into a socket outlet and switch the up your instrument and choose the desired test parameters. Navigation of this instrument on using the On/Off switch situated on the left side of the menuing system is by means of the cursor control and Enter key. instrument. The POWER lamp will illuminate, the instrument will display the firmware version number and perform a calibration check. If this is At the top of the screen are the three main menu choices; “TEST”, successful the display will show “CALIBRATED”. If the check fails the “OPTIONS” and “CURRENT”. display will show “NOT CALIBRATED”. Below this are details of the test current selected (SET CURRENT), maximum current to be allowed (CURRENT LIMIT), the number of stored tests and the current date and time. To perform a measurement is straightforward. 1. Use the Left and Right arrows of the two-axis cursor control to DLRO 200 V1.00 COPYRIGHT highlight the TEST menu. Use the down arrow to select the MEGGER LIMITED 2002 required test type. Press Enter. INITIALISING HARDWARE CALIBRATED 2. Use the Left and Right arrows of the two-axis cursor control to highlight the CURRENT menu. Use the down arrow to select SET and press Enter. Type in the desired current using the numeric keys on the keypad. When finished press Enter. After a slight pause the display will change to the Main Menu screen. If the current you have set is greater than the current limit, DLRO200 will beep and clear the SET CURRENT field. Re-enter the desired current, if necessary increasing the current limit to a value equal to or greater than the desired level. (See separate topic for setting the... -
Page 6: Test Menu
www.actoolsupply.com OPERATION Please note that if your DLRO200 is inadequately grounded / earthed it will securely connected to the item under test before pressing the Test button. not be possible to start a test. The DLRO200 checks voltage and current loop continuity as in Normal Mode and, if adequate, passes a continuous d.c. current, repeating resistance TEST Menu measurements at approximately 2-second intervals until the test is terminated The TEST menu allows the selection of one of three test modes - Normal, by pressing the Test button (or until the DLRO200 overheats if particularly Automatic or Continuous. Only one mode can be active at a time and the high currents are used). active mode is displayed below the heading TEST when you return to the MAIN MENU screen. CONTINUOUS mode is abbreviated to CONT under the TEST heading in the main menu screen. Normal Mode Overheating Normal mode makes a single measurement of the resistance of the sample under test. When operating continuously at 200 A, overheating will occur after approximately 15 minutes (assuming a starting temperature of 20ºC). A Please note that in this mode both the current and voltage leads must be message ‘HOT’ will then appear on the display until the internal parts have connected across the test sample before the Test button is pressed. When cooled. When the ‘HOT’ message is on the screen, test current is turned off the TEST button is pressed DLRO200 will check for good contact in the P and all front panel controls are disabled. circuit. If the P circuit continuity is faulty the display will show “POTENTIAL Operating at reduced current will considerably extend the operating time. FAIL”. Press the ENTER key to remove this message and adjust the contact of the P probes to ensure good contact is achieved. Press the TEST button Automatic Mode again. P circuit continuity will be checked and if satisfactory DLRO200 will In Automatic mode, only connect the current leads to the sample to be proceed to carry out a test. After a short period of time, if there is inadequate measured. Press the TEST button. The red status lamp next to the TEST contact in the C circuit the instrument will display “CURRENT LOOP... -
Page 7: Options Menu
www.actoolsupply.com OPERATION measure will then activate the measurement. the settings should be 9600 baud, 8 data bits, 1 stop bit, and no parity. AUTOMATIC mode is abbreviated to AUTO under the TEST heading in Downloading data does not cause the stored data to be erased from the main menu screen. AUTO mode may be exited by pressing the TEST memory. To clear data from memory see “Delete Data” below. button while the status light is flashing. Please note – DLRO200 also makes data available via the RS232 OPTIONS Menu Port in real time and is suitable for printing on a self-powered serial The Options menu has five selections, which control various ancillary printer. (See later for details.) functions and which are selected using the two-axis cursor control and The output has the following form: the Enter key. These are Retrieve, Passbands, Set Clock, Delete Data and Storage. Test Type Retrieve Test Number allows the recall of results which have been stored within the DLRO200’s Date Format internal memory. There are two choices, Display or Download. Date Display recalls each test, in sequence, to the instrument display starting with the Time most recently stored result. Use the cursor control Up and Down controls Selected Current to step later or earlier respectively through the stored results. Resistance If you know the number of the test that you wish to display simply type in the number and press Enter. Measured Current An asterisk (*) next to the word “MEMO” at the bottom of the screen Measured Voltage means that there are notes attached to this result. Press the right cursor... - Page 8 www.actoolsupply.com OPERATION Passbands displayed. The passband option allows you to set upper and lower limits between Use the cursor control Up and Down arrows to adjust the highlighted data. which the test result must lie if it is to be assigned a Pass. Readings that fall Step to the next item by using the Right cursor control arrow. above the upper limit or below the lower limit will be assigned a Fail. The row below DD MM YY HH MM contains respectively the date, the The upper and lower limits are entered via the keyboard complete with month, the two-digit year (21st century is assumed), the hour of the day in decimal points, where applicable, and including the m or µ symbol as 24-hour notation and the minute. These must be entered in this sequence appropriate. It is not necessary to enter the Ω symbol. Entering the m or µ regardless of the date format you wish to use. symbol tells DLRO200 that the entry in that particular field is complete and the cursor will therefore move to the next field. The upper limit must be The lower DD/MM/YY shows the current date format. Pressing the less than or equal to 999.9 mΩ and the lower limit must be less than the cursor control Up arrow will cycle through the available options DD/ upper limit. MM/YY, MM/DD/YY or YY/MM/DD. This is updated when you press Enter to exit the Set Clock function. However, tests already stored prior to After completing the upper and lower limits the cursor will move to the changing the date format will retain the old format. ENABLE or DISABLE options. Highlight your choice using the right and Delete Data left controls and press Enter. You will return to the Main Menu screen. Select Delete Data if you wish to clear DLRO200’s memory of stored data. Note: Passbands will remain enabled or disabled until you re-enter In case you have selected this Option by accident you will be asked to this screen and change the selection. If all that is required is to change confirm that you wish to delete the data. The default is NO. Change this Passbands from ENABLED to DISABLE or vice versa, enter the to YES and press Enter if you wish to delete all data.
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Page 9: Current Menu
www.actoolsupply.com OPERATION storing results. The main menu screen will also display “300 MEMORY Initially the Potential circuit is checked. If there is poor continuity in this circuit a message will appear on the display stating “POTENTIAL FAIL”. FULL” instead of the number of stored tests. Press Enter to clear this message and correct the discontinuity in the P Data is stored for up to 10 years in battery backed RAM. circuit. CURRENT Menu Press TEST again. If the P circuit is complete DLRO200 will attempt to There are two options, SET, and LIMIT. pass the test current. If the C circuit continuity is inadequate, after a little while, DLRO200 will display the message “CURRENT LOOP FAIL”. Press Enter to clear the message. Correct the fault and start the test again. This option allows you to set the desired test current. Simply enter the desired value using the numeric keys on the keyboard and press Enter. If External Voltage Warning the current selected is greater than the limit that has been set, DLRO200 The item being tested must be voltage free. If, at any time while DLRO200 will beep, cancel your entry in the Set Current field and wait for you to is connected, the item being tested has a voltage in excess of 10 volts ac enter a valid current. peak or dc with respect to the instrument ground potential, a message Limit “EXTERNAL VOLTAGE ON TERMINALS” will appear on the display. Some samples to be tested may not be able to withstand the passing of This is a warning that the item under test is live and might be dangerous. heavy currents. In this case set a maximum level of test current to prevent A test cannot be performed in this condition. the accidental entry of an excessive test current. This level defaults to Remove the external voltage. The display will revert to the main menu 200A. If a lower limit is required enter it using the keyboard and press... -
Page 10: Entering Notes In The Memo Screen
www.actoolsupply.com OPERATION ENTERING NOTES IN THE MEMO SCREEN DATE FORMAT DD/MM/YY At the end of each test you may add comments to the test results. Instead SET CURRENT 50 of pressing Enter to return to the Main Menu screen, briefly press any UPPER LIMIT 0.9990000 alphanumeric key. You will enter a MEMO screen that allows you to enter up to 160 characters of alphanumeric information concerning the test. When LOWER LIMIT 0.0000000 you have entered all information press Enter and the measurement and TEST TYPE NORMAL memo will be stored in memory. MEASURED RESISTANCE, CURRENT, VOLTAGE If you do not wish to add notes press the Test button and a new test will be started, or the Enter button to return to the Main Screen. MEASURED RESISTANCE, CURRENT, VOLTAGE MEASURED RESISTANCE, CURRENT, VOLTAGE TEST RESULT STORAGE Each test is numbered sequentially, dated and timed. The test result memory …………. can store a maximum of 300 tests, each being identified by its test number, MEASURED RESISTANCE, CURRENT, VOLTAGE date and time. When memory is full the message “MEMORY FULL” will be shown. Testing may continue but no more results will be stored. See Options MEASURED RESISTANCE, CURRENT, VOLTAGE Menu – Storage for more information. PASS or FAIL REAL TIME DOWNLOADING OF TEST DATA. The Upper and Lower limits are always shown in ohms. -
Page 11: Test Techniques & Applications
www.actoolsupply.com TEST TECHNIQUES & APPLICATIONS When using DLRO200 to measure low resistances at high currents, the used. heavy current leads should be securely connected to the item under test The size of the current leads will limit the maximum resistance which may using heavy-duty clips or clamps. The use of Duplex handspikes is not be measured at full current or may limit the maximum current output to a recommended. level somewhat less than 200 A. The DLRO200 can generate 200 Amps into Connect the four leads as shown. a total current loop resistance of 19 mΩ if the supply voltage is greater than 208 V r.m.s., or 11 mΩ for a supply voltage of 115 V r.m.s. The 50 mm leads supplied as standard with the DLRO200 (DLRO200-115 is supplied with 25 mm leads (4 mΩ each) have a resistance of 2 mΩ each at 20 C, and so the DLRO200 will be able to measure up to 15 mΩ (supply ο >207 V r.m.s.), or 7 mΩ (115 V r.m.s.), in the item under test at 200 A with It is important that the potential probes are positioned on the test sample leads at 20 ο C. As you pass 200 A the leads will warm up and their ability to inside the current probes. pass current will decrease as their resistance increases. Thicker or shorter current leads increase these limits. Test Sequence Pressing the TEST button or selecting AUTOMATIC mode starts the test Longer current leads are available if required. sequence. Interference And Grounding The Sample Continuity of the P1-P2 loop is checked by passing an ac current Ideally the test specimen should be grounded during the test. If it is not (approximately 100 mA @10 KHz) through the test leads and measuring... -
Page 12: Specifications
Temperature: Operation: -10 C to +50 *It is not possible to select a current less than 10 A but since the open Storage: C to +65 circuit terminal voltage is somewhere between 2 V and 5 V (if input power Calibration: 20 is 100 V to 250 V), actual test current can be as low as 2 A when loop Co-efficient: < 0.05% per resistance is 1 Ω. If actual current is less than 2 A a ‘Current loop fail’ will be reported. Humidity (max): 95% RH non-condensing Measurement: Modes: Manual, Auto, Continuous. Altitude (max): 2000 m Test Time: < 10 seconds NORMAL or Safety: IEC61010-1 AUTO mode, Refreshed every EMC: EN61326-1 2.4s in CONTINUOUS mode Operational inaccuracies: Refer to www.megger.com Display: Measurement: Large, high resolution backlit Dimensions: 410 x 250 x 250 mm liquid crystal display Weight: < 15 kg. www.actoolsupply.com... - Page 13 Megger is a registered trademark DLRO200_UG_en_V04 0810 www.actoolsupply.com...
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