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AVTM21- 415Ja 

Rev A 

June 2005 

 

 

 

15 kV Megohmmeter 

Test Set 

Catalog No. 210415 Series 

 

 

 

 

High-Voltage Equipment 

Read the entire manual before operating. 

 

Aparato de Alto Voltaje 

Antes de operar este producto lea este manual enteramente. 

 
 

 

 

 
 
 
 

2621 Van Buren Avenue 

Norristown, PA 19403 

1-800-723-2861 ext. 8578 

 

megger.com

 

 

 

Advanced Test Equipment Rentals

www.atecorp.com  800-404-ATEC (2832)

®

Established 1981

Summary of Contents for ATEC 210415 Series

Page 1: ...Equipment Read the entire manual before operating Aparato de Alto Voltaje Antes de operar este producto lea este manual enteramente 2621 Van Buren Avenue Norristown PA 19403 1 800 723 2861 ext 8578 m...

Page 2: ...15 kV Megohmmeter Test Set Catalog No 210415 Series M...

Page 3: ...the product or its individual instruments are used for purposes other than those specified herein confirmation of their validity and suitability must be obtained from Megger Specifications are subject...

Page 4: ...earances 21 8 OPERATION 27 Test Procedure 27 Breakdown of Test Item 28 Normal Shutdown Procedure 29 Interrupting a Test 29 9 OPERATION NOTES 31 Line Supply 31 Meter Range Settings During Transit 31 Me...

Page 5: ...of Output Cable W101 53 Replacement of Power Cord W1 54 Replacement of Meters or Meter Amplifier Board 55 Replacement of Megohmmeter Range Circuit 55 Replacement of Voltmeter Range Circuit 56 Replacem...

Page 6: ...re 7 DC Motor Test Setup 26 Figure 8 Generator Test Setup 26 Figure 9 Regulation Curves with Stabilizer OUT 120V Supply 37 Figure 10 Typical Guard Connection to Cable Pothead 38 Figure 11 Guard Connec...

Page 7: ...iv AVTM21 415Ja Rev A June 2005 List of Tables TABLE 1 Minimum Air Clearances 21 TABLE 2 Two Three Terminal Measurement Connection Schedule 44 TABLE 3 Trouble Location Chart 63...

Page 8: ...estions provided in this manual anticipate the normal use of the Megohmmeter Test Set for testing electrical insulation systems on such equipment as motors generators bushings and cables These tests w...

Page 9: ...M 2 AVTM21 415Ja Rev A June 2005 Figure 1 15 kV Megohmmeter Test Set Catalog No 210415...

Page 10: ...must be kept away from test activities by suitable barriers barricades or warnings The Test Set panel must be connected to a reliable local ground to prevent possible shock danger to the operator Sinc...

Page 11: ...ulating controls Megger considers this an excellent safety practice PACEMAKERS High voltage discharges and other sources of strong electric or magnetic fields may interfere with the proper functioning...

Page 12: ...If any damage is discovered file a claim with the carrier at once and notify Megger or its nearest authorized sales representative giving a detailed description of the damage observed This instrument...

Page 13: ...M 6 AVTM21 415Ja Rev A June 2005 M...

Page 14: ...rating 50 Hz reduced rating Basis of Rated Performance 120 Volt 60 Hz supply with stabilizer out OPTIONAL SUPPLY Catalog No 210415 47 Voltage rms Specify nominal voltage on order NOMINAL RANGE MAXIMUM...

Page 15: ...resistive load OUTPUT VOLTAGE REGULATION Internal Stabilizer Out 13 no load to 7 5 M load percent change in line voltage Internal Stabilizer In 0 1 no load to 300 M load including 10 line voltage chan...

Page 16: ...00 7 5 5 1 100 10 1000 100 10 000 1000 100 000 EITHER ANY up to 300 up to 3000 up to 30 000 up to 300 000 CONTROLS Power OFF ON switch Circuit Breaker with green lamp indicator High Voltage OFF ON swi...

Page 17: ...minal inch stud with wing nut External Instrument Jack Accepts inch 2 wire phone plug for connecting external recorder or current meter to read current in test item PHYSICAL Case High impact structura...

Page 18: ...ld use and transportation PROTECTIVE FEATURES Dual overload protection for all overload conditions by two separate circuit breakers Metering protected against overload and transient conditions SAFETY...

Page 19: ...M 12 AVTM21 415Ja Rev A June 2005 M...

Page 20: ...g of the output voltage and current passing between the high voltage output terminal and ground Figure 2 is the schematic diagram of this Test Set The high voltage dc power supply is contained within...

Page 21: ...rcuits For safety the path from Earth to the metering is paralleled by the green wire of the power cord W1 Within U1 is the megohmmeter transient protection capacitor C1 and voltage limiting Zener dio...

Page 22: ...coil of circuit breaker switch CB2 When S1 is set to the IN position stabilized voltage is applied to T1 through resistor R1 and a parallel path exists from the input of T1 to the circuit return thro...

Page 23: ...M 16 AVTM21 415Ja Rev A June 2005 Figure 2 Schematic Diagram of the 15 kV Megohmmeter...

Page 24: ...ON 1 Guard Terminal 7 Carrying Strap 2 23 Output Cable 8 Removable Case Cover 3 High Voltage Terminal 26 Location of 47 Option Step Down Transformer 4 Ground Cable 27 Lead Storage 5 25 Power Cord 6 In...

Page 25: ...brator 10 Megohmmeter Calibrator 18 Voltage Control 11 Megohm Multiplier Selector 19 AC ON Green Lamp 12 Megohmmeter 20 Input Power Switch 13 Stabilization Selector 21 Output ON Red Lamp 14 Kilovoltme...

Page 26: ...o safety identify the terminals of the apparatus to be tested Be sure that the low voltage terminal is securely grounded Provide a ground connection if necessary using wire of 18 AWG or larger Define...

Page 27: ...thout being exposed to traffic hazard he must have free access to all controls and be able to read the meters and panel markings easily without approaching energized high voltage terminals CONNECTIONS...

Page 28: ...ng the conductors in place with clean dry nylon rope Table I lists the minimum air clearances that must be maintained and also suggests the minimum path length along a rope if it is tied directly to a...

Page 29: ...the user A fuse of not less than 1 amperes or more than 3 amperes is recommended Because of the many different service sockets in general use the input cable has been provided with a plug for which a...

Page 30: ...SETTING UP 23 AVTM21 415Ja Rev A June 2005 Figure 4 Testing in a Substation...

Page 31: ...M 24 AVTM21 415Ja Rev A June 2005 Figure 5 Testing Parking Lot Lighting the Test Set Shown is Operating from an Inverter...

Page 32: ...SETTING UP 25 AVTM21 415Ja Rev A June 2005 Figure 6 Testing Transformer Terminals...

Page 33: ...M 26 AVTM21 415Ja Rev A June 2005 Figure 7 DC Motor Test Setup Figure 8 Generator Test Setup...

Page 34: ...paratus to be tested 2 Close the AC ON switch green lamp comes on If the service outlet voltage exceeds the rated limit for the Test Set the Power ON indicator will be abnormally bright This will warn...

Page 35: ...100 or 1000 see Section 9 12 To measure insulation resistance at 5 kV set the voltmeter range switch to 7 5 kV and set the output voltage to exactly 5 kV Use the lower red meter scale Read the megohmm...

Page 36: ...ed during the test use an insulated grounding stick to apply a direct short circuit to all ungrounded terminals of the apparatus being tested 4 Disconnect cables in the following sequence first the in...

Page 37: ...breakers will trip or they can be operated manually If the stabilizer is IN it is necessary to open either the HV ON or the AC ON switches manually to permanently de energize the test This procedure s...

Page 38: ...range switches be set as follows the voltmeter to 15 kV and the megohmmeter to the X1 position MEGOHM READINGS The megohmmeter is a current meter measuring the current passing through the item under t...

Page 39: ...RC indicated resistance on scale corresponding to selected VC RV actual resistance being measured at voltage V The factor V V c can be read directly from the lower green scale of the Voltmeter When t...

Page 40: ...measured resistance of item under test RT corrected measured resistance of item under test STABILIZING SWITCH In most cases the motion of the Megohmmeter pointer is slow and steady enough to permit a...

Page 41: ...n excluding the resistance of the surface path from the measurement See Figures 10 and 11 This is easily accomplished by forming an intercepting electrode by wrapping a bare wire around the outer surf...

Page 42: ...e on the order of 5 to 10 depending on the line voltage and the nature of the apparatus being tested USE OF REGULATION CURVE The regulation curve given in Figure 9 applies when the stabilizer is OUT a...

Page 43: ...ust beyond the voltage that causes arc over it is possible that the arc over will repeat several times before trip out During this time the operator can look for the light and noise generated by the s...

Page 44: ...or adding series resistance When series resistance is added care must be taken to avoid hazards from the new connection When using the stabilizer in the IN position the voltage control should be set...

Page 45: ...M 38 AVTM21 415Ja Rev A June 2005 Figure 10 Typical Guard Connection to Cable Pothead Figure 11 Guard Connection for a Typical Cable Test...

Page 46: ...OPERATION NOTES 39 AVTM21 415Ja Rev A June 2005 Figure 12 Typical Guard Connection for an Oil Circuit Breaker Figure 13 Typical Guard Connection for Transformer Test...

Page 47: ...M 40 AVTM21 415Ja Rev A June 2005 M...

Page 48: ...f methods and measurements may be taken to anticipate such failures Each method has its own merits but one technique is to apply a dc voltage to the insulation system and measure such quantities as th...

Page 49: ...connected to ground One side of the apparatus being tested must be connected to ground This minimizes exposure of high voltage leads and conforms to the way most apparatus is constructed This leaves...

Page 50: ...nd without guard can be extended to other apparatus in order to separate multiple resistance paths and so better analyze the situation In some literature the unguarded measurement is called a two term...

Page 51: ...ordance with Table 2 TABLE 2 Two and Three Terminal Measurement Connection Schedule CONNECTIONS MEASUREMENT HIGH VOLTAGE GROUND GUARD r12 1 2 Not Used r12 1 2 3 r23 3 2 1 r12 r12 r23 r12r23 r13 r12 r1...

Page 52: ...one junction grounded Many problems can be reduced to this form and then evaluated by the technique given above The additional effort required to carry out the study to reduce the problem to a ground...

Page 53: ...M 46 AVTM21 415Ja Rev A June 2005 M...

Page 54: ...phere this procedure should be performed once every six months as an extreme the procedure should be carried out monthly on a set that is used daily outdoors in a heavy dust concentration that is cond...

Page 55: ...all knobs are secure on their shafts and that all controls operate smoothly without binding 5 Set meters mechanically to left scale end 6 Removal of Test Set from Case G CAUTION The test set must be...

Page 56: ...tion of Inspection a Wipe the circuit card with a clean dry cloth to remove accumulated dust Wipe the interior of the case Visually inspect the interior connections and components b Re install the gua...

Page 57: ...M 50 AVTM21 415Ja Rev A June 2005 M...

Page 58: ...items which can be returned separately for repair are indicated in the parts list by an asterisk following the part number Upon their return to the factory such items will be repaired or replaced whi...

Page 59: ...must also be understood so that measures may be taken to prevent shock hazard to those making repairs When making repairs to this test set or replacing components the procedures outlined in the follow...

Page 60: ...e insulation spacer blocks that are located between chassis and panel 9 Follow these steps in reverse order for re assembly For Catalog No 210415 47 Test Sets it is necessary to first disconnect the t...

Page 61: ...versed to install the replacement If not the replacement cable should be prepared to duplicate the original cable before installation REPLACEMENT OF POWER CORD W1 1 Separate chassis and panel 2 Turn p...

Page 62: ...ide the meter from the panel 6 Replace the meter and reverse the above steps to complete the repair REPLACEMENT OF MEGOHMMETER RANGE CIRCUIT 1 Remove the range switch knob switch shaft locknut and was...

Page 63: ...he shaft 5 Re solder the leads to the printed circuit card REPLACEMENT OF STABILIZING SWITCH S1 1 Separate panel and chassis 2 Mark and remove the leads from the switch 3 Carefully note the location o...

Page 64: ...leads noting the appropriate reconnection terminal for each 2 Remove the voltage control knob 3 Remove the bushing nut 4 Pull the transformer free of the assembly 5 Replace the transformer through th...

Page 65: ...k the splice insulation to transformer lead 5 Carefully unsolder the connection to free the transformer lead 6 Mark and remove the leads connected to the capacitors 7 Remove the screws holding the Zen...

Page 66: ...adjustment and an output of 10 kV Check at 15 kV full scale 7 Replace both CAL cover screws CALIBRATION OF MEGOHMMETER Calibration accuracy is a function of the voltmeter accuracy Always calibrate the...

Page 67: ...MOCAL adjustment This adjustment applies also to the X1 and X100 ranges Proceed as follows using the 10 megohm load resistor 1 Set multiplier to X10 standard meter for 500 A 2 Increase output for a cu...

Page 68: ...Zener diodes CR1 and CR2 at maximum line voltage and minimum burden output current on the test set Catalog No 210415 Remove the test set from the case Locate R1 on the rear of the panel see interior...

Page 69: ...he resistor moving the tap to the right increases resistance If the observed value is less than calculated in Step k decrease the resistance of R1 to the left m Repeat Steps i through k and continue u...

Page 70: ...witch trips on closure Internal wiring short circuit Defective socket DS1 Defective K2 Defective CR1 or CR2 Stabilizer IN No red lamp when OUTPUT ON switch is closed and voltage control is at zero Def...

Page 71: ...R104 Defective M101 Defective W101 No megohmmeter reading Guard connected to ground Range switch set too low Defective M102 Defective U1 Defective J1 W101 not connected to apparatus under test No gro...

Page 72: ...rve Incorrect supply voltage Voltage control knob not in proper position on shaft Defect in R104 Defect in U2 Output voltage greater than 0 25 kV with voltage control at 0 Improper adjustment of K2 me...

Page 73: ...M 66 AVTM21 415Ja Rev A June 2005 Figure 15A Interior View Figure 15B Interior View...

Page 74: ...TROUBLESHOOTING REPAIR 67 AVTM21 415Ja Rev A June 2005 Figure 16 Connections for Calibration of Voltmeter Figure 17 Connections for Calibration of the Megohmmeter...

Page 75: ...M 68 AVTM21 415Ja Rev A June 2005 M...

Page 76: ...ring this test persons conducting the test must be familiar with the safety precautions normally followed when operating high voltage equipment and must take all necessary measures to avoid shock haza...

Page 77: ...ohmmeter range to X1 stabilizer OUT 8 Operate the set and very carefully turn up the voltage control Note that the megohmmeter moves to full deflection 9 After reaching full scale on the X1 megohm ran...

Page 78: ...6580 2 W1 Input cable power cord 17032 W101 Output cable 10586 W102 Ground cable 4702 CB1 AC ON switch 4709 CB2 HV ON switch 4710 DS1 DS2 Lamps only 6S6 125 1723 T1 Voltage control 6408 2 R1 Stabilize...

Page 79: ...r protective capacitor 7950 M101 Voltmeter 25295 S101 Voltmeter range selector PC 22521 R104 Output current limit resistor 4500 101 U1 Megohmmeter protective range selector PC 4986 M102 Megohmmeter 25...

Page 80: ...de batteries lamps or tubes where the original manufacturer s warranty shall apply WE MAKE NO OTHER WARRANTY The warranty is void in the event of abuse or failure by the customer to perform specified...

Page 81: ...M 74 AVTM21 415Ja Rev A June 2005 M...

Page 82: ...M 2621 Van Buren Avenue Norristown PA 19403 1 800 723 2861 ext 8578 megger com...

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