ED&D LT-952HC User Manual Download Page 17

 

PRODUCT SAFETY SOLUTIONS

 

 

© 2017 Educated Design & Development, Inc. All rights reserved. Rev C 

                             

          

Page 16 of 19 

Problem: The meter fuse blows

Solution:  Confirm  that  the  fuse  being  used  is  the  correct  type  and  rating  as  indicated  in  the  Maintenance 
Section of this Manual. 

Solution: The device under test is inadvertently grounded through another connecting cable.  This happens 
frequently  when  testing  computers.    The  extra  ground  can  come  from  a  monitor  or  other  cord  connected 
peripheral.    To  avoid  another  blown  fuse,  verify  that  there  are  no  extra  grounds  by  measuring  with  an 
ohmmeter before trying to measure leakage. 

Solution: The device under test is connected to earth ground through the mounting means or from connection 
to a grounded water pipe.  This can be the case when testing stationary cord connected equipment.  If this is 
the case, please refer to “Field Testing Grounded Products”, chapter 2. 

Solution: Do not change test conditions while holding the Ground switch in the OPEN position.  This causes 
momentary  transients  that  will  blow  the  fuse.    Depress  the  Ground  switch  only  long  enough  to  take  a 
measurement. 

Problem: The front panel AC receptacle is dead. 

Solution: The front panel receptacle is designed to be disabled whenever the LT-952HC is connected to a 
240 Volt source.  Check the position of the rear panel Voltage Selector switch. 

Solution: The rear panel circuit breaker has tripped due to an overload.  Reset the circuit breaker.  Verify that 
the input current to the device under test does not exceed 20 Amps when using the front panel receptacle. 

Solution: The Neutral Switch is set to OPEN 

Problem The meter on the LT-952HC indicates a single "1" with the remaining 3 digits blanked. 

Solution: This indicates an over range condition.  Switch to the higher 20mA range.  If already on the 20mA 
range, the product under test has excessively high leakage or there is a ground path from the device under 
test (possibly via an accessory cable). 

Problem  The  meter  display  is  blank  and  the  Ground  Closed  indicator  does  not  light  when  the  LT-
952HC is turned on. 

Solution: Check to make sure that the LT-952HC is receiving power and that the Voltage Selector switch is in 
the proper position.  Check the Line Fuse on the LT-952HC. 

Problem The Line fuse on the LT-952HC blows

Solution: Check to make sure it is the correct type and rating as indicated in the Maintenance Section of the 
Manual. 

Solution: Verify that the rear panel Voltage Selector switch is in the proper position.  The Line fuse is  

 

 

 

Summary of Contents for LT-952HC

Page 1: ...PRODUCT SAFETY SOLUTIONS USER S MANUAL LEAKAGE CURRENT TESTER MODEL LT 952HC...

Page 2: ...s 2 Product purpose 2 Understanding Leakage Current 3 Before using 5 PRODUCT COMPONENTS 6 PRODUCT SPECIFICATIONS 10 OPERATING INSTRUCTIONS 11 THEORY OF OPERATION 14 REFERENCE STANDARDS 17 MAINTENANCE...

Page 3: ...CURRENT TESTING IS INHERENTLY HAZARDOUS RISK OF ELECTRIC SHOCK KEEP HANDS AND FINGERS AWAY FROM ENERGIZED COMPONENTS AT ALL TIMES NO USER SERICEABLE PARTS INSIDE SERVICING BY QUALIFIED SERVICE PERSON...

Page 4: ...easure leakage from surface to surface or surface to ground as required by many Safety Standards Rear panel jacks provide access to the Body Circuit Impedance to observe the wave shape of the leakage...

Page 5: ...meter with precision impedance correlating to the impedance of the human body is used to represent the human body Extensive tests have been done to approximate the impedance of the human body These t...

Page 6: ...before attempting to use the Leakage Tester Operation and use of the LT 952HC is to be performed by Qualified Personnel ONLY WARNING Person s using this device should have proper education training i...

Page 7: ...Front Panel A Neutral Open Closed Switch B Line Forward Reverse Switch C Ground Open Closed Switch D LCD Display E Power On Off Switch F D U T Device Under Test Receptacle G Open Closed Ground Indicat...

Page 8: ...hould be lit For safety the LT 952HC is designed to disable both the front and rear panel outlets when the power switch is OFF F D U T OUTLET Provides a convenient way to connect 120 Volt 15 Amp produ...

Page 9: ...er measurement circuit is connected to the meter reference This connection is used to measure the leakage between an exposed metal surface and the meter reference point PRODUCT COMPONENTS Rear Panel W...

Page 10: ...r source B VOLTAGE SELECT SWITCH This switch configures the LT 952HC to run off either 100 120 or 200 240 VAC The switch must be set to the proper position before power is applied to the LT 952HC C D...

Page 11: ...70 C Humidity 80 R H 0 C to 35 C Overall Dimensions 11 1 2 in W x 13 1 2 in D x 5 1 4 H in 29 2 cm W x 34 3 cm D x 13 33 cm H Overall Weight 9 0 lb 4 0 Kg Body Circuit Precision network in accordance...

Page 12: ...verify that there are no other grounds to the equipment under test connect an ohmmeter between the ground pin on the product under test and the power system ground Readings of close to 0 Ohms indicat...

Page 13: ...at you or another person cannot accidentally come into contact with the product during the test Since the product ground is disconnected while the Ground switch is toggled OPEN the product under test...

Page 14: ...Within a few seconds the display on the LT 952HC should settle to the final leakage current value If the displayed result is less than 20mA operate the Range switch to the 2mA position 8 IEC60950 spe...

Page 15: ...MEASUREMENT CIRCUIT THE RESULT IS EXCESSIVE CURRENT THROUGH THE METER THAT CAN CAUSE THE METER FUSE TO BLOW THEORY OF OPERATION This section of the manual contains a description of the circuitry used...

Page 16: ...l banana jacks meter reference switch and ground switching circuit The front panel Meter Connection switch a DP3T type is used to select between the various inputs The three possible meter connections...

Page 17: ...tacle is dead Solution The front panel receptacle is designed to be disabled whenever the LT 952HC is connected to a 240 Volt source Check the position of the rear panel Voltage Selector switch Soluti...

Page 18: ...meter circuit to the ground REFERENCE STANDARDS 60950 60335 and IEC 1010 based Standards MAINTENANCE STORAGE See the instructions in the Calibration section of this manual No other periodic maintenan...

Page 19: ...able to generate technically valid results The exclusive use of calibration service providers which have been recognized by an independent accreditation body as conforming to the requirements of ISO...

Page 20: ...unit caused by excessive overload Furthermore this warranty does not cover damage caused by use of any attachment not original equipment of the product In addition ED D shall not be liable for any da...

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