1210N 1250N
Contents
1. 16 4 1 7 Insulation Resistance Measurements on Motors 19 4 2 Using the Model 1250N 995955955550009 99955556 21 4 2 1 Instrument Ground 18 8 4 21 4 2 2 0 8 9 6 eee 44455 eeeeeeeaeeeaaeeeeeeeeeeeesnaaeeeeeeeees 21 4 2 3 Safety Check Voltage Test cece 21 4 2 4 Utilization of the Guard Terminal 21 4 2 5 Insulation Resistance Testing MQ Range 23 4 2 6 Successful Insulation Resistance 165 6 25 4 2 7 Insulation Measurement 0 5 25 4 2 8 Insulation Resistance Measurements on Motors 28 5 3 8 30 SA MaM 30 0 1 1 1 11 16182595 eaters ds 30 Repair and 81 8 0 5 a 31 Technical and Sales Assistance 555559 31 Limited Warranty a eh cased S2. cccccccccessssteeeeeeeeeees 4 1 3 Receiving Your 5 16 4 1 4 Ordering Information 9555 5 4 5 4 1 4 1 Accessories and Replacement Parts 5 4 PRODUCT 8 5 9 8 8 8 8 8 8 5 2 1 DOSCHIPTION ve2 02pcces edpeceeesdycdesiedyedevescyevevie EEA EEA a RE EA i pE a EEK 5 2 2 Model 1210N Features 0 ccceecceeceeeeeeeeeneeeeeeeeeeeeeaeeeeeeeeeeeeaea 6 2 3 Model 1250N Features 5 5555 6 2 4 Model 1210N Control 6 5 5555 055555509 555559 5555 7 2 5 Model 1250N Control 6 5 5555545555 8 2 6 1210N and 1250N Control Features 4 9 5 5 9 555 9 5 1015 55929 555 55 5 55 10 3 1 Model 1210N Specifications 555 55555995555559 5555 10 3
3. ing on a DC circuit the pointer will deflect but the measurement may be inaccurate 4 2 4 Utilization of the Guard Terminal E Exposed surface A Insulation B Shield C Conductor Figure 13 Megohmmeter Models 1210N 1250N 21 Guard terminals are useful when measuring high resistance values and for stabilizing readings When testing the insulation at the end of a cable it is necessary to eliminate the error from surface leakage which occurs particularly at high resistance values The purpose of the guard terminal is to provide a third terminal within the path of the surface leakage E Connect the instrument as shown in Figure 13 If there is no shield at B use a copper wire wound several times around the exposed surface B Note If a shield is not available and you do not make up a shield around B and connect to the guard terminal the measurement will be erroneous and lead to confusion as to the cable s state If the guard terminal is not connected at B the instrument measures the current I flowing through the insulation and a surface leakage current i1 See Figure 14 NO CONNECTION to Guard terminal B R bad resistance through insulation Ry surface resistance Rz surface resistance To EARTH To LINE terminal terminal Figure 14 22 Megohmmeter Models 1210N 1250N When the guard terminal is connected at B the inst
4. a AEMC Instruments 15 Faraday Drive Dover NH 03820 USA Phone 800 945 2362 Ext 360 603 749 6434 Ext 360 Fax 603 742 2346 or 603 749 6309 E mail repair aemc com Caution To protect yourself against in transit loss we recommend you insure your returned material NOTE You must obtain a CSA before returning any instrument 32 Megohmmeter Models 1210N 1250N GJ AEMG INSTRUMENTS 09 08 99 MAN 100124 v11 Chauvin Arnoux Inc d b a AEMC Instruments 15 Faraday Drive Dover NH 03820 USA Phone 603 749 6434 Fax 603 742 2346 www aemc com
5. appears to be damaged file a claim immediately with the car rier and notify your distributor at once giving a detailed description of any damage Save the damaged packing container to substantiate your claim Do not use an instrument that appears to be damaged 1 4 Ordering Information Megohmmeter Model 1210 Cat 1326 01 Megohmmeter Model 1250 Cat 1326 02 Both models include a carrying strap with lead pouch three color coded leads ground lead two insulated alligator clips test probe and user manual 1 4 1 Accessories and Replacement Parts Set of 10 fuses 0 2A 250V fast blow 5x20mm 0 Cat 2973 02 Lead pouch with three color coded safety leads ground lead two safety alligator clips and test probe Cat 1019 01 Lead pouch with three color coded leads ground lead two alligator clips and test probe Cat 1017 56 4 Megohmmeter Models 1210N 1250N CHAPTER 2 PRODUCT FEATURES 2 1 Description The AEMC Models 1210N and 1250N are compact self contained hand cranked megohmmeters They are practical and dependable instruments designed for a broad range of plant and field service applications such as acceptance testing and preventive maintenance of wiring cables switchgear and motors The easy hand cranked operation provides a steady rectified DC voltage output a
6. deterioration of equip ment over its life Consult your equipment manufacturer for specific test or test voltage if not known Insulation resistance decreases with moisture temperature and age and should be recorded over time at a given temperature and corrected Megohmmeter Models 1210N 1250N 15 4 1 5 Successful Insulation Resistance Testing e Check with the equipment manufacturer for factory insulation resis tance readings Do not rely on insulation resistance testing alone as proof of winding conditions Do not expect the same value for all parts of all machines Observe consistent test time duration recognizing that total current through insulation under test will vary with time Correct all readings properly to a standard reference temperature see IEEE std 43 2000 Temperature Correction Curve Know what you are testing Isolate the piece of equipment from other circuitry Watch trends rather than relying on single spot readings 4 1 6 Insulation Measurement Connections Figure 3 shows the connections to measure the insulation of one conduc tor to the other conductors The cable should be disconnected at both ends to avoid leakage through switchboards and panels 16 on Under Test Cable Insulation Figure 3 Megohmmeter Models 1210N 1250N Figures 4 and 5 show the connections for testing insulation from a supply conductor to ground motor frame pea Under Test Cable Insulat
7. 1 1 Electrical 5 6 3 59555 955 55 10 3 1 2 Mechanical Specifications 55 55955 95555 11 3 1 3 Safety Specifications 5555 95555509555559 55555 11 3 2 Model 1250N Specifications 5555 55 5555 585555 5 12 3 2 1 Electrical 5 3 555555 5555 5 55550 12 3 2 2 Mechanical Specifications 55 5555 95555 12 3 2 3 Safety Specifications 5555 4555555045555509 5555 13 8 110 3 30 3535 45 9 8 89 14 4 1 Using the Model 1210N 999955555559999999555 14 4 1 1 Instrument Ground 16 1 814 55 9 14 44 2 SAULO PANQING 14 4 1 3 Safety Check Voltage Test 14 4 1 4 Insulation Resistance Testing MQ Range 14 4 1 5 Successful Insulation Resistance 165 6 16 4 1 6 Insulation Measurement Connections
8. 1210N 1250N JAEMC User Manual INSTRUMENTS Statement of Compliance Chauvin Arnoux Inc d b a AEMC Instruments certifies that this instrument has been calibrated using standards and instruments traceable to international standards We guarantee that at the time of shipping your instrument has met its published specifications An NIST traceable certificate may be requested at the time of purchase or obtained by returning the instrument to our repair and calibration facility for a nominal charge The recommended calibration interval for this instrument is 12 months and begins on the date of receipt by the customer For recalibration please use our Calibration services Refer to our repair and calibration section at www aemc com Serial Catalog 1326 01 1326 02 Model 1210 1250 Please fill in the appropriate date as indicated Date Received Date Calibration Due Chauvin Arnoux Inc d b a AEMC Instruments INSTRUMENTS www aemc com ee ee Table of Contents 8 10 2 3 3 3 3 39 3 9 3 8 8 8 9 8 8 3 1 1 International Electrical 5 5015 55555 5555 55 3 1 2 Definition of Measurement Categories
9. 17 Figure 18 shows the connections to a transformer lighting or distribution Make sure that the switches and or circuit breakers on both sides are open Check the high voltage winding to ground low voltage to ground and the resistance between them with no winding ground Transformer Grounding Lug Figure 18 26 Megohmmeter Models 1210N 1250N Figure 19 shows the connections for measuring the insulation of a three phase line to ground by connecting the jumpers between phases This gives a reading of all conductors at once If a load such as a motor heater etc is attached to the other end of the line it will read the load resistance to ground at the same time By removing the jumpers readings can be made between the individual conductors and ground Jumpers Figure 19 Megohmmeter Models 1210N 1250N 27 4 2 8 Insulation Resistance Measurements on Motors Figure 20 shows reading the resistance to ground of a three phase motor winding Since the three phase motors are internally connected it is only necessary to connect one lead to the motor lead and the other lead to the motor frame as shown Figure 20 Figure 21 shows the windings of a three phase motor separated Some times this can be done at the lead terminals while other times the end bells must be removed to get at the lead wires of the coils By connecting the megohmmeter as shown the phase insulation resistance value can now be determined Read betwee
10. as required by other standards or internal procedures For instrument repair and calibration You must contact our Service Center for a Customer Service Authorization Number CSA This will ensure that when your instrument arrives it will be tracked and processed promptly Please write the CSA on the outside of the shipping container If the instrument is returned for calibration we need to know if you want a standard calibration or a calibration traceable to N I S T Includes calibration certificate plus recorded calibration data Ship To Chauvin Arnoux Inc d b a AEMC Instruments 15 Faraday Drive Dover NH 03820 USA Phone 800 945 2362 Ext 360 603 749 6434 Ext 360 Fax 603 742 2346 or 603 749 6309 E mail repair aemc com Or contact your authorized distributor Costs for repair standard calibration and calibration traceable to N I S T are available NOTE You must obtain a CSA before returning any instrument Technical and Sales Assistance If you are experiencing any technical problems or require any assistance with the proper operation or application of your instrument please call mail fax or e mail our technical support team Chauvin Arnoux Inc d b a AEMC Instruments 200 Foxborough Boulevard Foxborough MA 02035 USA Phone 800 343 1391 508 698 2115 Fax 508 698 2118 E mail techsupport aemc com www aemc com NOTE Do not ship Instruments to our Foxborough MA address M
11. ate front panel O ring seal between front panel and case sealed against water and dust folding crank Terminals Line red earth black accepts standard 4mm safety banana plugs ground accepts 4mm banana plug or spade lugs 3 1 3 Safety Specifications Sealed IP54 with lid IP52 without lid Insulation Tester VDE 413 part 1 4 except f Safety IEC1010 1 600V CAT II 1000V CAT Envelope Protection IEC529 Vibration MIL T 38800D Shock IEC51 Megohmmeter Models 1210N 1250N 11 3 2 Model 1250N Specifications 3 2 1 Electrical Specifications INSULATION TESTS DC Test Voltages 250 500 1000V Test voltages generated in full across the entire measurement range Megohm Ranges Auto ranging 250V 1 to 11MQ 11 to 500MQ 500V 1 to 11MQ 11 to 500MQ 1000V 10 to 110MQ 110 to 5000MQ Short Circuit Current 5mA approx Accuracy 2 of full scale length Charging Time 250V 0 2 s uF 500V 0 5 s uF 1000V 0 5 5 Discharging Time Auto 8 s UF VOLTAGE TESTS Safety Check Voltage Range 0 to 600VAC Accuracy 3 of full scale 3 2 2 Mechanical Specifications Test Voltage Indicator Green LED indicates proper test voltage and crank speed Warning the crank speed LED is not ON during test ing the reading is not valid Scale Direct readings on all ranges 3 76mm black on white 12 Megohmmeter Models 1210N 1250N Autorange Indicator Red LED indicates autorange multipl
12. cross the entire range for consistently reliable readings These megohmmeters incorporate a built in sealed alternator and a constant DC voltage circuit to provide a stable output and give direct insulation resistance reading They are ruggedly built and use an O ring sealed cast aluminum case with a polycarbonate front panel designed for harsh heavy duty use and protection against dust and water The Models 1210N 1250N have a unique auto ranging feature which expands the scale by x10 and almost doubles the scale length When the pointer reaches near the end of scale the auto ranging feature activates returning the pointer to the beginning of the scale with the x10 red LED indicator on Insulation resistance is indicated with a rugged taut band meter move ment on a logarithmic scale The indicator scale is easy to read Megohmmeter Models 1210N 1250N 5 2 2 2 3 Model 1210N Features Measures insulation at 500V resistance continuity Test voltage constant across the entire measurement range Autoranging MQ kQ and Q ranges Designed for harsh environments offshore mining heavy duty field industrial and military use Extra rugged cast aluminum case O ring sealed against rain water and dust aluminum lid Compact self contained package folding crank Large direct reading scale 600V test voltage range safety check Model 1250N Features Three test voltages 250 500 1000V Test voltage constant across the enti
13. egohmmeter Models 1210N 1250N 31 Limited Warranty The Models 1210N and 1250N are warranted to the owner for a period of one year from the date of original purchase against defects in manufacture This limited warranty is given by AEMC Instruments not by the distributor from whom it was purchased This warranty is void if the unit has been tampered with abused or if the defect is related to service not performed by AEMC Instruments For full and detailed warranty coverage please read the Warranty Coverage Information which is attached to the Warranty Registration Card if enclosed or is available at www aemc com Please keep the Warranty Coverage Information with your records What AEMC Instruments will do If a malfunction occurs within the one year period you may return the instrument to us for repair provided we have your warranty registration information on file or a proof of purchase AEMC Instruments will at its option repair or replace the faulty material REGISTER ONLINE AT www aemc com Warranty Repairs What you must do to return an Instrument for Warranty Repair First request a Customer Service Authorization Number CSA by phone or by fax from our Service Department see address below then return the instrument along with the signed CSA Form Please write the CSA on the outside of the shipping container Return the instrument postage or shipment pre paid to Ship To Chauvin Arnoux Inc d b
14. ervicing the instrument This symbol on the instrument indicates a WARNING and that the operator must refer to the user manual for instructions before operating the instrument In this manual the symbol preceding instructions indicates that ifthe instructions are not followed bodily injury installation sample and product damage may result 1 1 E This symbol signifies that the instrument is protected by double or rein Risk of electric shock The voltage at the parts marked with this symbol may be dangerous Megohmmeter Models 1210N 1250N 3 1 2 Definition of Measurement Categories Cat 1 For measurements on circuits not directly connected to the AC supply wall outlet such as protected secondaries signal level and limited energy circuits Cat Il For measurements performed on circuits directly connected to the electrical distribution system Examples are measurements on household appliances or portable tools Cat Ill For measurements performed in the building installation at the distribution level such as on hardwired equipment in fixed installation and circuit breakers Cat IV For measurements performed at the primary electrical supply lt 1000V such as on primary overcurrent protection devices ripple control units or meters 1 3 Receiving Your Shipment Upon receiving your shipment make sure that the contents are consistent with the packing list Notify your distributor of any missing items If the equipment
15. eti A hig saad 32 Warranty Repair S cccceecceeessseececeeeeeeesteeeeeeeeeeeeeseaeeeeeeeeeseeesseeeaeeeeeenens 32 2 Megohmmeter Models 1210N 1250N CHAPTER 1 INTRODUCTION uN Warning These safety warnings are provided to ensure the safety of personnel and proper operation of the instrument Read the instruction manual completely and follow all safety information before operating this instrument Safety is the responsibility of the operator Tests are to be carried out only on dead circuits Check for live circuits before making resistance measurements safety check The Megohmmeter Models 1210N 1250N are sources of high voltage as is the sample connected to them All persons perform ing or assisting in the tests must employ all safety precautions to prevent electrical shock to themselves and to others AEMC Instruments considers the use of rubber gloves to be an excellent safety practice even if the equipment is properly operated and correctly grounded When testing capacitance samples make sure that they have been properly discharged and that they are safe to touch Dielectric insulation samples should be short circuited for at least five times the amount of time they were energized Use the leads supplied with the megohmmeter If defective or used replace before testing International Electrical Symbols forced insulation Use only specified replacement parts when s
16. ion Figure 4 a Under Test Cable Insulation Figure 5 Figure 6 shows the connections to a transformer lighting or distribution Make sure that the switches and or circuit breakers on both sides are open Check the high voltage winding to ground low voltage to ground and the resistance between them with no winding ground Megohmmeter Models 1210N 1250N 17 Tested Winding Transformer Grounding Lug Figure 6 Figure 7 shows the connections for measuring the insulation of a three phase line to ground by connecting the jumpers between phases This gives a reading of all conductors at once If a load such as a motor heater etc is attached to the other end of the line it will read the load resistance to ground at the same time By removing the jumpers readings can be made between the individual conductors and ground Jumpers Figure 7 18 Megohmmeter Models 1210N 1250N 4 1 7 Insulation Resistance Measurements on Motors Figure 8 shows reading the resistance to ground of a three phase motor winding Since the three phase motors are internally connected it is only necessary to connect one lead to the motor lead and the other lead to the motor frame as shown 0000000000000 Figure 8 Figure 9 shows the windings of a three phase motor separated Some times this can be done at the lead terminals while other times the end bells must be removed to get at the lead wires of the coils By c
17. minimum value should be measured The IEEE standard N 43 2000 states that it is impossible to specify the value of insulation resistance at which a winding will fail electri cally but on motors minimum readings generally stated are Rated Voltage R minimum 250 or less 2 MQ 460 2 MQ There is no fixed figure for determining what is good and bad in resistance readings but a good guide would be 1 megohm for every one hundred applied operating volts as a minimum figure This applies to motors and transformers When the insulation resistance gets this low an electrical break down can be expected at any time and rewinding or replacing should be considered It is not unusual for a winding to be 10 to 100 times the recommended minimum value IEEE standard 43 2000 Recommended Practice for Testing Insulation Resistance of Rotating Machinery but this varies with temperature and humidity RATIO TESTING In time resistance reading Dielectric Absorption Ratio readings are taken at 30 seconds and 60 seconds to obtain the dielectric absorption ratio Insulation resistance 60s Dielectric Absorption ratio DAR Insulation resistance 30s This test is useful to increase the accuracy of spot testing In general a ratio of 1 25 2 or better should be required A ratio below this indicates that repair is probably needed Remember that a DC insulation test may be used for acceptance testing but is more commonly used to check the gradual
18. mpossible to specify the value of insulation resistance at which a winding will fail electri cally but on motors minimum readings generally stated are Rated Voltage R minimum 250 or less 2 MQ 460 2 MQ There is no fixed figure for determining what is good and bad in resistance readings but a good guide would be 1 megohm for every one hundred applied operating volts as a minimum figure This applies to motors and transformers When the insulation resistance gets this low an electrical break down can be expected at any time and rewinding or replacing should be considered It is not unusual for a winding to be 10 to 100 times the recommended minimum value IEEE standard 43 2000 Recommended Practice for Testing Insulation Resistance of Rotating Machinery but this varies with temperature and humidity RATIO TESTING In time resistance reading Dielectric Absorption Ratio readings are taken at 30 seconds and 60 seconds to obtain the dielectric absorption ratio Insulation resistance 60s Dielectric Absorption ratio DAR Insulation resistance 30s This test is useful to increase the accuracy of spot testing In general a ratio of 1 25 2 or better should be required A ratio below this indicates that repair is probably needed Remember that a DC insulation test may be used for acceptance testing but is more commonly used to check the gradual deterioration of equip ment over its life Consult your equipment manufacturer fo
19. n phases and B then B and C then C and A Figure 21 28 Megohmmeter Models 1210N 1250N Figure 22 shows connections for testing insulation from a supply conduc tor in a switchbox to ground motor frame An identical test may be carried out from the motor starter Motor Side of Switch Connection to One Leg Starter In Grounded Motor Frame Figure 22 Megohmmeter Models 1210N 1250N 29 CHAPTER 5 MAINTENANCE 5 1 Warning For maintenance use only original factory replacement parts e To avoid electrical shock do not attempt to perform any servicing unless you are qualified to do so Do not perform any service while the Megohmmeter Model 1210N 1250N is on any circuit e To avoid electrical shock and or damage to the instrument do not let water or other foreign agents into the electronic module Warning If the crank speed LED is not ON during testing the reading is not valid 5 2 Cleaning The megohmmeter may be gently cleaned with a soft cloth soap and water Dry immediately after cleaning Avoid water penetration into the electronic module Make sure the megohmmeter and all leads are dry before further use 30 Megohmmeter Models 1210N 1250N Repair and Calibration To ensure that your instrument meets factory specifications we recommend that it be scheduled back to our factory Service Center at one year intervals for recalibration or
20. oltage Foldaway handle Mechanical zero adjustment screw Range switch Safety test first on 500 V V range to 500VAC Autoranging Red LED illuminates when reading needs to be multiplied x10 to obtain the true value MQ range Security finger rest isolates users hand from terminals while giving a firm grip during an operation Megohmmeter Models 1210N 1250N 2 6 1210N and 1250N Control Features Figure 2 Megohmmeter Models 1210N 1250N 11 12 13 14 15 16 17 18 19 20 Long sturdy assembly bolts for tight case closing Instrument ground terminal for enhanced user safety Rugged taut band meter movement Switch slide assembly Alternator crank shaft gears and bearings permanently lubricated and sealed Foldaway crank Die cast aluminum case cover not shown O ring construction seals out dirt and water Simple printed circuit board assembly for easy calibration and maintenance High impact polycar bonate face plate CHAPTER 3 SPECIFICATIONS 3 1 Model 1210N Specifications 3 1 1 Electrical Specifications INSULATION TESTS DC Test Voltage 500V test voltage generated in full across the entire measurement range Megohm Range Auto ranging 0 5 to 5 5MQ 5 5 to 200MQ Short Circuit Current 5mA max Accuracy 2 5 of full scale length Charging Time 0 5 5 Discharging Time Auto 5 5 RESISTANCE TESTS DC Test Current 1mA c
21. onnecting the megohmmeter as shown the phase insulation resistance value can now be determined Read between phases A and B then B and C then C and A gt Figure 9 Megohmmeter Models 1210N 1250N 19 Figure 10 shows connections for testing insulation from a supply conduc tor in a switchbox to ground motor frame An identical test may be carried out from the motor starter Motor Side of Switch Connection to One Leg Starter In Grounded Motor Frame Figure 10 20 Megohmmeter Models 1210N 1250N 4 2 Using the Model 1250N 4 2 1 Instrument Ground Terminal The Megohmmeter Model 1250N is equipped with an instrument ground terminal for enhanced user safety Ground your instrument when in use 4 2 2 Auto ranging How it works When the pointer reaches approximately 90 of the full scale length the auto range is triggered the red auto range x10 LED lights up The pointer goes back to the beginning of the scale and resumes its travel The readings should be multiplied by 10 when the x10 LED is on 4 2 3 Safety Check Voltage Test Before measuring insulation resistance confirm that the sample is fully discharged particularly in dielectric and capacitance samples and that the sample is not connected to an energized circuit To perform the voltage test set the range selection to 500V connect and read on the red voltage scale 600VAC max DO NOT CRANK If measur
22. onstant 600V max Kilohm Range Auto ranging 0 to 45kQ 45 to 500kQ Accuracy 2 5 full scale length Charging Time 0 5 s uF Discharging Time Auto 5 5 CONTINUITY TESTS DC Test Current 5mA constant 10V max Ohm Range Auto ranging 0 to 90 9 to 1009 Accuracy 2 of full scale length Fuse Protection 0 2A 250V fast blow 5x20mm VOLTAGE TESTS Safety Check Voltage Range 0 to 600VAC Frequency 45 to 450Hz Accuracy 3 of full scale Input Impedance 100kQ approx 10 Megohmmeter Models 1210 1250 3 1 2 Mechanical Specifications Test Voltage Indicator Amber LED indicates proper test voltage and crank speed Scale Direct readings on all ranges 3 76mm black on white Autorange Indicator Red LED indicates Auto range multiply resistance readings x 10 Power Supply Hand cranked heavy duty brushless alternator and solid state rectifica tion and amplification for stable voltage test voltage reached at 140 rpm approx Dielectric Test 2000V 50 60 Hz between and ground terminals Meter Movement Rugged taut band suspension Dimensions 4 7 x 4 7 x 5 1 120 x 120 x 130mm Weight 3 3 Ibs 1 5 kg Temperature Range Reference range 64 to 75 F 18 to 24 C 30 50 RH Operating range 14 to 122 F 10 to 50 C 0 80 RH Storage range 4 to 176 F 20 to 80 C 0 90 RH Case Cast aluminum alloy case and lid painted safety yellow with heavy duty gray polycarbon
23. r instrument when in use 4 1 2 Auto ranging How it works When the pointer reaches approximately 90 of the full scale length the auto range is triggered the red auto range x10 LED lights up The pointer goes back to the beginning of the scale and resumes its travel The readings should be multiplied by 10 when the x10 LED is on 4 1 3 Safety Check Voltage Test Before measuring insulation resistance confirm that the sample is fully discharged particularly in dielectric and capacitance samples and that the sample is not connected to an energized circuit To perform the voltage test set the range selection to V MQ connect and read on the red voltage scale 6G00VAC max DO NOT CRANK If measur ing on a DC circuit the pointer will deflect but the measurement may be inaccurate 4 1 4 Insulation Resistance Testing MQ Range After checking for a live circuit see Safety Check above select the MQ range and connect the megohmmeter Several connection examples are illustrated further Crank the handle until the amber LED on the upper right hand side lights ensuring appropriate test voltage at the output 14 Megohmmeter Models 1210N 1250N SPOT TESTING As a general rule in spot testing test voltage should be applied until no variation in reading is noted for 15 seconds or applied for a fixed 60 sec onds On capacitance circuits cranking for up to a minute or more may be necessary to fully charge the sample What
24. r specific test or test voltage if not known Insulation resistance decreases with moisture temperature and age and should be recorded over time at a given temperature and corrected 24 Megohmmeter Models 1210N 1250N 4 2 6 Successful Insulation Resistance Testing Check with the equipment manufacturer for factory insulation resis tance readings Do not rely on insulation resistance testing alone as proof of winding conditions Do not expect the same value for all parts of all machines Observe consistent test time duration recognizing that total current through insulation under test will vary with time Correct all readings properly to a standard reference temperature see IEEE std 43 2000 Temperature Correction Curve Know what you are testing Isolate the piece of equipment from other circuitry Watch trends rather than relying on single spot readings 4 2 7 Insulation Measurement Connections Figures 16 and 17 show the connections to measure the insulation of one conductor to the other conductors The connection to the guard terminal is used to eliminate the effects of surface leakage across exposed insulation at one end of the cable Refer to the section on Utilization of the Guard Terminal The cable should be disconnected at both ends to avoid leakage through switchboards and panels Under Test Cable Insulation Figure 16 Megohmmeter Models 1210N 1250N 25 Cable Insulation Figure
25. re measurement range Autoranging MQ ranges Designed for harsh environments offshore mining heavy duty field industrial and military use Extra rugged cast aluminum case O ring sealed against rain water and dust aluminum lid Compact self contained package folding crank Four terminals including guard and ground Large direct reading scale 600V test voltage range safety check Megohmmeter Models 1210N 1250N 2 4 Model 1210N Control Features a N oo N Megohmmeter Models 1210N 1250N Figure 1 Line terminal Black Fuse 0 2A Earth terminal Red Instrument ground terminal for user safety Amber LED illuminates when proper crank speed is attained indicating presence of selected output Foldaway handle Mechanical zero adjustment screw Range switch safety test first on MQ V range to 5 0 Autoranging Red LED illuminates when reading needs to be multiplied x10 to obtain the true value MQ KQ Q ranges Security finger rest isolates users hand from terminals while giving a firm grip during an operation 2 5 Model 1250N Control Features a oo N c MEGOHMMETER ents Model 1250N RU Figure 1 A Line terminal Black Guard terminal Blue Earth terminal Red Instrument ground terminal for user safety Green LED illuminates when proper crank speed is attained indicating presence of selected test v
26. rument measures the current I and not the surface leakage current i1 which is not included in the measurement See Figure 15 This type of measurement will give the true value of the resistance Rx providing the Ry and Rz are not too low To Guard terminal 1 Rx resistance through insulation Ry surface resistance Rz surface resistance To LINE A C terminal To EARTH terminal Figure 15 4 2 5 Insulation Resistance Testing MQ Range After checking for a live circuit see safety check select the test volt age and connect the megohmmeter Several connection examples are illustrated further Crank the handle until the green LED on the upper right hand side lights ensuring that the selected test voltage has been reached TEST VOLTAGE No published standard tells which voltage to choose for any given winding However published recommendations could be summarized as follows Rated Voltage of Motor Test Voltage Below 115 250V 115 250 or 500V 230 500V 460 500 or 1000V Megohmmeter Models 1210N 1250N 23 SPOT TESTING As a general rule in spot testing test voltage should be applied until no variation in reading is noted for 15 seconds or applied for a fixed 60 sec onds On capacitance circuits cranking for up to a minute or more may be necessary to fully charge the sample What minimum value should be measured The IEEE standard N 43 2000 states that it is i
27. y resistance readings x 10 Dielectric Test 2000V 50 60 Hz between guard and ground terminals Power Supply Hand cranked heavy duty brushless alternator and solid state rectifica tion and amplification for stable voltage test voltage reached at 140 approx Meter Movement Rugged taut band suspension Dimensions 4 7 x 4 7 x 5 1 120 x 120 x 130mm Weight 3 3 lbs 1 5 kg Temperature Range Reference range 64 to 75 F 18 to 24 C 30 50 RH Operating range 14 to 122 F 10 to 50 C 0 80 RH Storage range 4 to 176 F 20 to 80 C 0 90 RH Case Cast aluminum alloy case and lid painted safety yellow with heavy duty gray polycarbonate front panel O ring seal between front panel and case sealed against water and dust folding crank Terminals Line red earth black G guard blue accepts safety 4mm banana plugs ground accepts 4mm banana plugs or spade lug 3 2 3 Safety Specifications Sealed IP54 with lid IP52 without lid Insulation Tester VDE 413 part 1 4 except f Safety IEC1010 1 600V CAT 1000V CAT Envelope Protection IEC529 Vibration MIL T 38800D Shock IEC51 All specifications are subject to change without notice Megohmmeter Models 1210N 1250N 13 CHAPTER 4 OPERATION 4 1 Using the Model 1210N 4 1 1 Instrument Ground Terminal The Megohmmeter Model 1210N is equipped with an instrument ground terminal for enhanced user safety Ground you
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