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Megger DLRO Instruction Manual

Manual is about: Digital Low Resistance Ohmmeters

Summary of DLRO

  • Page 1

    Avtm24-1j rev a april 2006 instruction manual dlro ® digital low resistance ohmmeters catalog no. 247000 series m valley forge corporate center 2621 van buren avenue norristown, pa 19403-2329 u.S.A. 610-676-8500 www.Megger.Com advanced test equipment rentals www.Atecorp.Com 800-404-atec (2832) ® est...

  • Page 3: Dlro

    Dlro ® digital low resistance ohmmeters catalog no. 247000 series.

  • Page 4: Warranty

    Copyright© 2006 by megger. All rights reserved. The information presented in this manual is believed to be adequate for the intended use of the product. If the product or its individual instruments are used for purposes other than those specified herein, confirmation of their validity and suitabilit...

  • Page 5: Table of Contents

    Avtm24-1j rev a april 2006 i table of contents 1.0 10 ampere systems .....................................................................................1 section a introduction ............................................................1 section b safety precautions .................................

  • Page 6: List of Figures

    Avtm24-1j rev a april 2006 ii list of figures figure 1: cat. No. 247000 dlro instrument without charger ...Iii figure 2: various dlro unit combinations..................................... 6 figure 3: controls & connections........................................................21 figure 4: typical ...

  • Page 7

    Avtm24-1j rev a april 2006 iii figure 1: catalog no. 247000 dlro instrument without charger.

  • Page 8

    Avtm24-1j rev a april 2006 iv m.

  • Page 9: 1.0

    Avtm24-1j rev a april 2006 1 1.0 10 ampere systems section a introduction part 1.0 of this manual applies to a series of instruments; the principal models are catalog numbers 247000, 247001, 247002. Part 2.0 describes the 100 ampere systems including catalog numbers 247100, 247101 and 247120. The ca...

  • Page 10

    M avtm24-1j rev a april 2006 2 the catalog no. 247100 is a 100 ampere test system composed of a catalog no. 247000 measuring module, and a cat. No. 247120 100-amp power supply. The catalog no. 24701 is also a 100 ampere test system. The ohmmeter has four terminals for a kelvin connection to the samp...

  • Page 11: Section B

    Avtm24-1j rev a april 2006 3 section b safety precautions safety is the responsibility of the user la seguridad es la responsabilidad del operador f warning do not connect this instrument to energized circuits. The digital low resistance ohmmeters have been designed and constructed to meet the requi...

  • Page 12

    M avtm24-1j rev a april 2006 4 m.

  • Page 13: Section C

    Avtm24-1j rev a april 2006 5 section c receiving instructions read completely before operating your digital low resistance ohmmeter has been thoroughly tested and inspected to rigid specifications before being shipped and is ready for use. Check the equipment received against the packing list. Notif...

  • Page 14

    M avtm24-1j rev a april 2006 6 catalog no. 247000 with charger catalog no. 247001 catalog no. 247101with charger figure 2: various dlro unit combinations.

  • Page 15: Section D

    Avtm24-1j rev a april 2006 7 section d specifications ranges, resolution, accuracy & test current limit of error range test current amperes (±20%) resolution 1 year 15-35°c 1 year 0-50°c 0.000 -5.999 mo 10 1 µo ¼ % rdg + 1 lsd* ½ % rdg + 1lsd* 00.00 -59.99 mo 1 10 µo ¼ % rdg + 1 lsd* ½ % rdg + 1lsd*...

  • Page 16: Interference

    M avtm24-1j rev a april 2006 8 interference effects: error in item under test caused by line- frequency current of 0.1x test current: ±l lsd error caused by 5-gauss line- frequency magnetic field: ±2 lsd error caused by connection to ground or voltage to ground (assuming battery operation): none inp...

  • Page 17: Specifications

    Specifications avtm24-1j rev a april 2006 9 calibration adjustments: internal zero and span adjustments for all ranges. Test lead resistance requirements: potential leads (p1. P2): no limitations. Current leads (c1, c2): each lead 20 milliohms nominal. Deviations affect test current but do not affec...

  • Page 18: Battery

    M avtm24-1j rev a april 2006 10 battery charger: separate charger unit plugs into receptacle on measuring unit. Full charge in 14 hours. Charging may be continued while instrument is operating. Fused, with ul listed 3- wire line cord and plug. Power requirements, 0.22 amps at 115 volts, 50/60 hz; or...

  • Page 19: Specifications

    Specifications avtm24-1j rev a april 2006 11 safety: meets all applicable requirements of ansi/isa s82.01-1994. Highest voltage existing (except in charger primary and line supply primary) is 6 volts. Case: the measuring unit and charger have rugged molded case with handles and removable hinged lids...

  • Page 20: For 10-Ampere Systems

    M avtm24-1j rev a april 2006 12 catalog numbers and unit combinations for 10-ampere systems catalog no. Description 247000 instrument with internal rechargeable batteries and separate 115v 50/60 hz charger unit. Range: 0 to 60 ohms in 5 ranges, 0 to 5.999 milliohms lowest range (note 1). 247000-3 sa...

  • Page 21: Specifications

    Specifications avtm24-1j rev a april 2006 13 catalog numbers and unit combinations for 10-ampere systems catalog no. Description 247100 see part 2.0 247101 see part 2.0 247120 see part 2.0 notes: note 1: leads not included. (see bulletin 24-1 for recommended test leads.) see page 36 for information ...

  • Page 22

    M avtm24-1j rev a april 2006 14 m.

  • Page 23: Section E

    Avtm24-1j rev a april 2006 15 section e circuit description ra and ra’ set the test current to the values listed in section 0, specifications; there is a pair of these resistors for each range. On the 6 m Ω 10a range, test current is also affected by the resistance of the test leads connected to the...

  • Page 24

    M avtm24-1j rev a april 2006 16 the display would be: ) m ( 500 . 1 v 060 . 0 a 10 0015 . 0 6 Ω = × Ω × if the test current is reduced to 9 amperes: ) m ( 500 . 1 v 054 . 0 a 9 0015 . 0 6 Ω = × Ω × thus the reading is independent of test current variations caused by changes in battery voltage, or by...

  • Page 25: Circuit Descriptions

    Circuit descriptions avtm24-1j rev a april 2006 17 batteries, even if they are allowed to remain on charge indefinitely. Charging currents are set at the factory and need readjustment only when batteries are replaced. Zener diodes protect the instrument from damage caused by switching transients tha...

  • Page 26

    M avtm24-1j rev a april 2006 18 m.

  • Page 27: Section F

    Avtm24-1j rev a april 2006 19 section f controls and connections fig. 3 shows a front panel view of catalog no. 247000 with functional parts and operating controls labeled. S4, m1 battery test meter m1 shows the relative state of charge of the internal rechargeable batteries. With s4 in the “display...

  • Page 28: C1, P1, P2, C2

    M avtm24-1j rev a april 2006 20 c1, p1, p2, c2 four terminals with wing—nuts are provided for making a kelvin connection to the specimen under test. Test current is available at the c1 and c2 terminals, and the actual resistance is measured between the points where leads connected to the p1 and p2 t...

  • Page 29: Controls & Connections

    Controls & connections avtm24-1j rev a april 2006 21 figure 3: controls & connections c1 p1 p2 c2 s2 s3 s1 s4 m1 j2.

  • Page 30

    M avtm24-1j rev a april 2006 22 m.

  • Page 31: Section G

    Avtm24-1j rev a april 2006 23 section g operating procedure rechargeable battery models § battery check before using the instrument, check the display and measuring circuit batteries. The battery test meter will indicate their relative state of charge. The battery test is valid only when the instrum...

  • Page 32: Very Low Resistance

    M avtm24-1j rev a april 2006 24 § very low resistance for full accuracy when reading below 0.1 mo, use the average of forward and reverse readings. Make the reverse reading by holding the “forward-reverse” switch in the “reverse” position. A minus (—) sign will appear in the display when this switch...

  • Page 33: Operating Procedure

    Operating procedure avtm24-1j rev a april 2006 25 3. Using kelvin clip leads. Figure 4: typical connections to a test sample. 4. Charging batteries to charge the batteries, remove the jumper plug from j2 and connect the output lead of the battery charger to j2. A pilot light on the charger will indi...

  • Page 34

    M avtm24-1j rev a april 2006 26 m.

  • Page 35: Section H

    Avtm24-1j rev a april 2006 27 section h applications measuring contact resistance of circuit breakers biddle cat. No. 241004-18 duplex clamp leads are recommended for this application. Connect the leads as shown in fig, 3. For safety, one terminal of the sample must be grounded. Measuring winding re...

  • Page 36: Measuring Winding Resistance

    M avtm24-1j rev a april 2006 28 for personnel safety and to protect the dlro instrument, proceed as follows: 1. Firmly connect c1and c2 leads before switching the dlro on. 2. Switch the dlro off before disconnecting cl or c2 connections. Measuring winding resistance of electric motors fig.3b shows h...

  • Page 37: Applications

    Applications avtm24-1j rev a april 2006 29 interference alternating current interference in the sample under test can cause several digits fluctuation in a displayed reading. Interference can also be due to pickup in long test leads, especially in the vicinity of strong electric or magnetic fields. ...

  • Page 38

    M avtm24-1j rev a april 2006 30 when making a measurement of a totally new kind, interchange the c leads to determine whether there is any dc interference..

  • Page 39: Section I

    Avtm24-1j rev a april 2006 31 section i maintenance remove the instrument from its case by removing the screws at each corner of the panel. Rechargeable batteries the internal rechargeable batteries may fail to hold a charge after several hundred charge-discharge cycles, resulting in shorter than no...

  • Page 40

    M avtm24-1j rev a april 2006 32 after batteries are replaced, charging currents must be checked and, if necessary, readjusted to accommodate the characteristics of the new cells. Contact megger for instructions..

  • Page 41: Section J

    Avtm24-1j rev a april 2006 33 section j field replaceable parts list cat. Nos. 247000, 247000-47 part no. Qty. Description see table 1 battery charger, complete 5026 4 wing nut 4690-5 1 knob 15568-2 2 b2,b3 1.25v, size f, 7 a.H. Nickel-cadmium rechargeable battery (gould 7.0 scb or equivalent) 15568...

  • Page 42: Catalog Nos. 247001, 247002

    M avtm24-1j rev a april 2006 34 catalog nos. 247001, 247002 part no. Qty. Description 5026 4 wing nut 25774 1 knob (247001) 15568-2 2 b2, b3 1.25v, size f, 7 a.H. Nickel-cadmium rechargeable battery (gould 7.0 scb or equivalent) 15568-1 4 b1 1.25v, size f, 4 a.H. Nickel-cadmium rechargeable battery ...

  • Page 43: Section K

    Avtm24-1j rev a april 2006 35 section k warranty & repair warranty: all products supplied by megger are warranted against all defects in material and workmanship for a period of one year following shipment. Our liability is specifically limited to replacing or repairing, at our option, defective equ...

  • Page 44

    M avtm24-1j rev a april 2006 36 shipped prepaid and insured and marked for the attention. Of the instrument service manager. Figure 5: cat. No. 247101 dlro consists of three elements: left: 100a current source center: measuring module right: charger module for measuring module.

  • Page 45: 2.0

    Avtm24-1j rev a april 2006 37 2.0 100 ampere system section a introduction the catalog no. 247100 dlro instrument is a digital low resistance ohmmeter designed specifically to measure very low resistance (zero to 600 micro-ohms) with a test current of 100 amperes. This capability is required by some...

  • Page 46: Iec 61166 Ed. 1.0, B:1993

    M avtm24-1j rev a april 2006 38 flowing in the circuit and shall not exceed the limit set for the rating by the manufacturer”. Iec 61166 ed. 1.0, b:1993 high-voltage alternating-current circuit-breakers part 4: type tests and routine tests paragraph 3.1 measurement of the résistance of the main circ...

  • Page 47: Introduction

    Introduction avtm24-1j rev a april 2006 39 this part of the manual covers only the 100-ampere portion of the system. Refer to part i for complete instructions for the basic cat. No. 247000 instrument..

  • Page 48

    M avtm24-1j rev a april 2006 40 m.

  • Page 49: Section B

    Avtm24-1j rev a april 2006 41 section b safety safety is the responsibility of the user la seguridad es la responsabilidad del operador f warning do not connect this instrument to energized circuits. The line-operated 100-ampere current source should be used and maintained by trained personnel who a...

  • Page 50

    M avtm24-1j rev a april 2006 42 m.

  • Page 51: Section C

    Avtm24-1j rev a april 2006 43 section c description & specifications description the components of the measuring system are as follows: 1. Compact dlro measuring module with rechargeable battery in molded case. 2. Battery charger in similar molded case. 3. 100-ampere dc current source having four te...

  • Page 52

    M avtm24-1j rev a april 2006 44 247100 complete 100 amp. System for 115v operation; includes 247000-3, 247120. 247100-47 complete 100 amp. System for 230v operation; includes 247000-3-47, 247120-47. 247101 complete 100 amp system for 115 v operation; includes 247001-3 & 247120 247101-47 complete 100...

  • Page 53: Description & Specifications

    Description & specifications avtm24-1j rev a april 2006 45 specifications measurement data limit of error range test current amperes resolution 1 year 15-35°c 1 year 0-50°c 000.0 - 600.0 mo 100 0.1 µo ½ % rdg + 2 lsd* 1 % rdg + 2 lsd* *(least significant digit) response time: (after on—off switch is...

  • Page 54: Dimensions:

    M avtm24-1j rev a april 2006 46 dimensions: 13 ½” wide x 9 ½” deep x 7 1/2” high (34.2 x 29.1 x 19 cm) test lead requirements: potential leads (p1, p2): no limitations. Current leads (c1, c2): 6.7 milliohms each. Deviations will not affect accuracy, but resistance changes may result in less than 100...

  • Page 55: Section D

    Avtm24-1j rev a april 2006 47 section d operating procedure follow the safety precautions of section b measurements on 600µo (100-ampere) dlro range 1. Connections and turn-on connect the test sample to the terminals as shown in figure 13. Make sure the current connections are clean and tight. Provi...

  • Page 56: 3.  Test Time

    M avtm24-1j rev a april 2006 48 2. Test current adjustment test current indicated on the ammeter should be 100a. If adjustment is necessary, it can be made by the current adjustment knob. Fluctuations in test current may be caused by line voltage swings or poor connections. 3. Test time reading will...

  • Page 57: Operating Procedure

    Operating procedure avtm24-1j rev a april 2006 49 figure 6: arrangement for making measurements in the 100- ampere range the maximum duty cycle for rated accuracy is: at 50°c ambient: continuous. 4. Display the display reads directly in micro-ohms regardless of the range switch setting on the instru...

  • Page 58: Measurements On Higher

    M avtm24-1j rev a april 2006 50 measurements on higher resistance ranges to use the instrument on its other ranges, replace the small jumper plug in the panel. Operation is now as described for cat. No. 247000 in part 1..

  • Page 59: Section E

    Avtm24-1j rev a april 2006 51 section e maintenance before calibrating the 600 micro-ohm range, be sure that the measuring module is calibrated as shown in part i. Connect the test leads to a resistance standard of about 100 micro-ohms which will tolerate 100 amperes. A “reichsanstalt” type standard...

  • Page 60

    M avtm24-1j rev a april 2006 52 m.

  • Page 61: Section G

    Avtm24-1j rev a april 2006 53 section g recommended test leads megger test leads recommended for use with the 100- ampere range are as follows: potential leads, pair, with single hand spikes: cat. No. 242021-7 5 ft. #14 awg. Cat. No. 242021-18 20 ft. #10 awg. Cat. No. 242021-30 31 ft. # 8 awg. Curre...

  • Page 62

    M avtm24-1j rev a april 2006 54 m.

  • Page 63: Section H

    Avtm24-1j rev a april 2006 55 section h warranty and repair warranty all products supplied by megger are warranted against all defects in material and workmanship for a period of one year following shipment. Our liability is specifically limited to replacing or repairing, at our option, defective eq...

  • Page 64

    M avtm24-1j rev a april 2006 56 prepaid and insured and marked for the attention of the instrument service manager..

  • Page 65: Section J

    Avtm24-1j rev a april 2006 57 section j field replaceable parts list part no. Qty description 4127-1 1 input cable.

  • Page 66

    M avtm24-1j rev a april 2006 58 m.

  • Page 67: -11 Option Input Protection

    Avtm24-1j rev a april 2006 59 -11 option input protection the revised circuit does not degrade calibration or performance. The customer must use the same rating fuses as provided on original installation (one set of spare fuses supplied with instrument. The safety precaution “do not connect this ins...

  • Page 68

    M avtm24-1j rev a april 2006 60 m.