User`s Manual Low Voltage Megohmmeter Model 380350
Contents
1. voltage is present on the device under test DO NOT proceed to test with voltage present Shock to the user and damage to the meter or device under test can result if testing is done with voltage present Proceed with testing only when the voltage is removed from the device under test Power Test Status LED When the meter is actively testing the Power Test status LED will blink When this status LED is flashing DO NOT touch the test leads or any exposed parts in the testing area Hazardous voltages exist that can cause shock If the Power Test LED fails to light the batteries must be replaced Refer to the Maintenance section near the end of this manual Low Resistance Tests WARNING Do not run this test unless the voltage on the device under test is zero Do not use this mode to check diodes or other semiconductor devices If the Live Circuit status LED lights when a test is initiated immediately abort the test and check that the circuit under test is not powered 1 Set the Function select switch to the Resistance position 2 Connect the red test lead to the LINE input and the black lead to the EARTH input 3 Perform a zero adjustment using the zero adjust screw on the display as described earlier 4 Connect the other ends of the test leads to the circuit under test and read the resistance on the green display scale The maximum resistance is 50Q AC Voltage Tests 1 Set the Function select switch to the red ACV2. 600V position 2 Connect the red test lead to the LINE input and the black test lead to EARTH 3 Connect the other end of the test leads IN PARALLEL to the circuit under test 4 Read the voltage value on the red display scale 6 380350 V1 4 11 2003 Maintenance Battery Replacement If the red Power Test status LED no longer lights when a test is initiated the eight 1 5 V AA batteries must be replaced 1 2 3 4 5 Ensure that the meter is not in the test mode and that the test leads aren t connected Remove the phillips head screw on the rear battery compartment cover Remove the battery compartment cover Replace the eight AA batteries ensuring proper polarity Affix the rear cover and secure the rear screw Fuse Replacements To test for an open fuse first assure that the batteries are not defective and then proceed as follows 1 Connect the test leads to the meter and short the clip ends of the test leads 2 Set the function switch to the ohms position and press the TEST button 3 If the fuse is open blown the pointer will indicate an open circuit max resistance 4 To locate the fuse open the rear battery fuse compartment via the Phillips head screw located at the center of the meter case 5 Replace the fuse 250V 1A fast acting located in the battery fuse compartment just above the batteries to the right Secure the battery fuse cover Cleaning Periodically wipe the case with a dry
3. User s Manual EXTECH INSTRUMENTS Low Voltage Megohmmeter Analog Insulation Tester plus AC Voltage and Continuity Tests Model 380350 SCALE MULTIPLIER 125Vx1 LIVE CIRCUIT 250V x2 DO NOT OPERATE FUT N POWER cE FUNCTION EXTECH 380350 LOW VOLTAGE MEGOHMMETER Introduction Congratulations on your purchase of Extech s Low Voltage Megohmmeter This meter is geared toward low voltage insulation testing applications such as Information Technologies and Telecommunications In addition to Megohmmeter Insulation Resistance measurements low Resistance and AC Voltage can be measured This professional meter with proper care will provide years of safe reliable service Safety Circuits under test must be de energized and isolated before connections are made except for voltage measurements Circuit connections must not be touched during a test Use extreme caution when working near bare conductors and bus bars Accidental contact with conductor could result in electrical shock Use caution when working near voltages above 60VDC or 30VACrms After insulation tests capacitors must be discharged Test leads including alligator clips must be in good working order clean and without broken or cracked insulation When servicing use only specified replacement parts International Safety Symbols Caution refer to this manual before using this meter Dangerous Voltage
4. cloth Do not use solvents or abrasives Do not allow water to seep into the meter case 7 380350 V1 4 11 2003 Calibration and Repair Services Extech offers repair and calibration services for the products we sell Extech also provides NIST certification for most products Call the Customer Service Department for information on calibration services available for this product Extech recommends that annual calibrations be performed to verify meter performance and accuracy Warranty EXTECH INSTRUMENTS CORPORATION warrants this instrument to be free of defects in parts and workmanship for one year from date of shipment a six month limited warranty applies on sensors and cables If it should become necessary to return the instrument for service during or beyond the warranty period contact the Customer Service Department at 781 890 7440 ext 210 for authorization or visit our website at www extech com click on Contact Extech and go to Service Department to request an RA number A Return Authorization RA number must be issued before any product is returned to Extech The sender is responsible for shipping charges freight insurance and proper packaging to prevent damage in transit This warranty does not apply to defects resulting from action of the user such as misuse improper wiring operation outside of specification improper maintenance or repair or unauthorized modification Extech specifically disclaims any implie
5. ct the meter leads to the circuit under test before pressing the TEST button Do not touch the clip ends of the test leads when the TEST button is pressed Some electrical equipment especially cables may retain an electrical charge when disconnected from the line It is good practice to discharge such equipment with grounding straps or other suitable devices before testing The meter automatically discharges the test circuits when the spring loaded TEST button is released Connecting Test Leads For all functions Megohmmeter Low Resistance and AC Voltage connect the red test lead to the LINE terminal and the black lead to the EARTH terminal Mechanical Zero Adjust Insert the test leads into the meter and short the free ends of the test leads Set the function switch to the ohms position and push the TEST button to the test position Carefully adjust the mechanical zero screw for a zero ohms reading Test Lead Check Set the rotary switch to the low resistance position Q Connect the leads to the meter and short the clip ends of the test leads and read the green resistance scale on the display The resistance should read between 0 and 0 5Q The display should read maximum range with the leads open not shorted If any readings are obtained other than the readings just described the test leads should be considered faulty and must be replaced before using the meter Failure to do so could result in damage to equipment and electrical sh
6. d warranties or merchantability or fitness for a specific purpose and will not be liable for any direct indirect incidental or consequential damages Extech s total liability is limited to repair or replacement of the product The warranty set forth above is inclusive and no other warranty whether written or oral is expressed or implied T Support Hotline 781 890 7440 Tech support Ext 200 Email support extech com Repair Returns Ext 210 Email repair extech com Website www extech com Copyright 2003 Extech Instruments Corporation All rights reserved including the right of reproduction in whole or in part in any form 8 380350 V1 4 11 2003
7. er Range Accurac Short circuit Overload y current Protection 0 to 20MQ 50VDC 10 5 of 2mA 250Vrms 0 to 5OMQ 125VDC 10 reading 0 to 100MQ 250VDC 10 3 380350 V1 4 11 2003 Meter Description Analog Display Live Circuit status LED Pointer zero adjustment screw Power Test status LED TEST pushbutton with Lock function Function select switch 3 Battery compartment on rear Test lead EARTH input jack Test lead LINE input jack 10 Test lead storage compartment OC OAONOARWN SR LOW VOLTAGE MEGOHMMETER I OD oF Analog Scale Description 1 125V 50MQ Megohmmeter Scale multiply reading by 2 for 250V 100MQ range 2 50V 20MQ Megohmmeter Scale Low Resistance Scale 0 to 50Q 4 AC Voltage Measurement Scale 0 to 600V w MULTIPLIER 600 125V xt ACV 4 250V x2 There are two Scales for the Megohmmeter Insulation Resistance measurements The top scale No 1 in diagram is used for the 125V 50MQ range This same top scale is also used for the 250V 100MQ range but the user must multiply the reading by 2 Scale No 2 in the diagram is used for the 50V 20MQ range only Scale No 3 in the diagram is used for low resistance measurements Scale No 4 is used for AC voltage measurements 4 380350 V1 4 11 2003 Operation Measurement Precautions Refer to the earlier Safety section for detail safety information Always conne
8. ock Insulation Resistance Megohmmeter Testing 50V 20MQ 125V 50MQ 250V 100MQ Connect the red test lead to the LINE input jack and connect the black test lead to the EARTH input jack Connect the other ends of the test leads to the device under test Turn the rotary switch to the desired range and press and hold down the TEST button To lock the TEST button down turn the TEST button to the right after pressing it down The resistance reading will display until the TEST button is released To interpret the Insulation Resistance reading on the Analog display scale refer to the previous section entitled Analog Scales Description Note on large installations In large wiring installations where the insulation of outlets is being tested more than one measurement may have to be made to take into account parallel resistances Divide large systems into subgroups and test subgroups individually Also in large installations the capacitance of the insulation will be high thereby taking longer to charge when being tested Care must be taken not to finish a measurement until the insulation capacitance is fully charged a steady stable reading is an indication that this is the case The charge stored in the insulation after a test will be discharged automatically when the test button is released Be careful not to turn the range switch while the test button is pressed 5 380350 V1 4 11 2003 Live Circuit Status LED If the Live Circuit status LED is lit
9. s Meter is protected throughout by double or reinforced insulation Rated Environmental Conditions Indoor use only Installation Category III Pollution degree 2 Altitude up to 2000 meters Ambient conditions Temperature 32 to 104 F 0 to 40 C RH 80 max 2 380350 V1 4 11 2003 Specifications General specifications Display Taut band multi scale analog display with Power Test and Live Circuit status LEDs and zero screw adjust Insulation test ranges 20 50 100MQ 50V 125V 250V tests AC Voltage test 600VAC measurements 40 to 1kHz Low Resistance 0 to 50Q Live circuit indicator LED lights when live circuit is sensed Withstand voltage Meets IEC 1010 safety requirements for Cat III 600V Power source Eight 1 5 AA cells included Power consumption Megohmmeter 160mA max Continuity 120 mA max Fuse protection 250V 1A for Insulation Resistance and Continuity Tests Operating conditions 32 to 104 F 0 to 40 C lt 80 RH Dimensions 6 7 x 6 5 x 3 6 170 x 165 x 92mm Weight 2 1 Ibs 970g Range Specifications Low Resistance Range Max open circuit Accuracy Overload Volt Protect 0 to 500 600mV 240mA 5 of scale 250Vrms length AC Voltage Range Accuracy Line Frequency 600VAC 2 5 of full 40 to 1kHz scale Insulation Resistance Megohmmet
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