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OPERATING INSTRUCTIONS

Ground Resistance Measurement

1. Open the jaws and make sure that the mating surfaces are clean and free of dust, dirt or any 

foreign substance.

2. Snap the jaws a few times to ensure clean contact is made.

3. Turn the rotary switch to the 

position to power the instrument on. Do not clamp on to any 

conductor or open the jaws, as this is a self-calibration phase.

4. At power on in _ mode, the instrument will perform a self-calibration for optimum accuracy. Users 

must

wait for self-calibration to be complete before use.  During the self-calibration phase, the 

LCD will show CAL7, CAL6, CAL5, CAL4, CAL 3, CAL2, and CAL1. 

5. When the ground tester is ready, a beep will be heard.

6. Place the clamp around the electrode or ground rod to be measured. Operate the jaws a few 

times for better accuracy.

7. Read the value of Rg (ground resistance) from LCD.

NOTE: For better measurement:

1. Operate the jaws a few times before powering on to clear mating surfaces.

2. Do not clamp on to any conductor during power up (point 3 above).

3. Operate the jaws a few times after clamping around the ground electrode.

NOTE: If self-calibration does not complete (The instrument will continue the process until a
successful self-calibration is achieved):

1. Check the jaw mating surfaces. If there is any dirt, dust, or any foreign substance, clean the 

surfaces.

2. Ensure the jaws are not open during self-calibration.

NOTE: Noise present in the electrode or ground rod. 

If there is excessive current or over 30V noise in the ground rod, a symbol of "NOISE" will be shown
in LCD. Under these conditions, the reading is no longer accurate. We recommend the current flow is
measured before a resistance reading is taken. 

NOTE: If jaws are opened during a measurement, a symbol of "OPEN" will be displayed on the LCD.

High and Low Alarm (

)

1. Set the rotary switch to the 

position. 

2. Press the FUNC button to select "HI" or "LO" alarm. The present value of High or Low alarm will 

be shown in the lower row of the LCD.

3. Press the 

button to increment the value by 1 ohm. If the button is held down, the rate of

increment accelerates. The value can be set from 0 ohm to 1550 ohm and then OL. The value will
roll over to 1(HI) or 0 (LO) if the set value in incremented past OL.

4. Once the value is set, press the FUNC button several times until the upper row LCD does not show

any letters.

6

Summary of Contents for DET10C

Page 1: ...M DET10C and DET20C Clamp on Ground Resistance Tester User Manual...

Page 2: ...und tester to twist or pry the ground electrode or ground wire away from the equipment being grounded All metal objects or wires connected to the electrical system should be assumed to be lethal until...

Page 3: ...ng Interval 8 Data Logging 8 Downloading Data to a PC DET20C only 8 Format of Down Loaded Data DET20C only 9 Reading the Data Stored in Memory 9 Clearing the Data Memory 9 Enable RS 232C output DET20C...

Page 4: ...esistance tester enables the user to measure the ground resistance of a ground rod without the use of auxiliary ground rods The clamp on ground resistance tester is used in multi grounded systems with...

Page 5: ...CD panel 5 REC button Function dependant on mode Starts either data logging single measurement recording or data download to PC Also used to increment a value in conjunction with FUNC button 6 FUNC bu...

Page 6: ...Indicates ground resistance tester senses noise or excessive current present in the ground electrode 7 Jaw Open Displayed if the jaws are opened during the measurement this symbol and word OPEN will b...

Page 7: ...amping around the ground electrode NOTE If self calibration does not complete The instrument will continue the process until a successful self calibration is achieved 1 Check the jaw mating surfaces I...

Page 8: ...ction is disabled The HI or LO value can be disabled individually NOTE The HI value cannot be lower than the LO value Similarly the LO value cannot be higher than the HI value HI value will be adjuste...

Page 9: ...REC will be shown on the LCD Data will be recorded at the specified sampling interval Data logging will be stopped if the memory is full or the unit detects a low battery condition or the REC button...

Page 10: ...tion OPEN Jaws open NS Noise HI Hi alarm LO Low alarm HD Data Hold LB Battery low Example of down loaded data 0001 sampling time 10 00 ohm 10 02 ohm 5 200 ohm LO 1 000 ohm NS 1 500 mA 9 00 A NOTE Each...

Page 11: ...putted every 0 5 seconds NOTE The RS 232C output is automatically disabled if data logging is in progress Installation of Megger Download Manager Software DET20C The DET20C instrument is supplied as s...

Page 12: ...plified typical ground distribution system The equivalent circuit is shown in Figure A If R1 R2 R3 Rn are simplified to Req then only Rg and Req are left in the circuit refer to Figure B If a constant...

Page 13: ...12 Rg Rg Req R1 R1 R2 R2 R3 R3 Rn Rn Figure A Figure B...

Page 14: ...and Low Alarm Range Resolution High Alarm 0 1550 1 Lo Alarm 0 1550 1 Ground Leakage Current Auto range 50 60 Hz True RMS Crest Factor 3 5 Range Resolution Accuracy of Reading 0 200 1 000 mA 0 001 mA 2...

Page 15: ...Down 5 minutes approx Sampling Time 0 5 seconds Operating Temperature 0 C to 50 C 14 F to 122 F Operating Humidity Less than 85 RH Storage Temperature 20 C to 60 C 4 F to 122 F Storage Humidity Less t...

Page 16: ...ery with a new battery Remove instrument from test piece during battery change 1 Turn the switch to the OFF position 2 Unfasten the battery cover screw 3 Lift and remove the battery cover 4 Remove the...

Page 17: ...unauthorized prior repair or adjustment will automatically invalidate the Warranty Instrument Repair and Spare Parts For service requirements for Megger Instruments contact Megger Limited or Megger Ar...

Page 18: ...APPES France T 33 1 30 16 08 90 F 33 1 34 61 23 77 OTHER TECHNICAL SALES OFFICES Toronto CANADA Sydney AUSTRALIA Madrid SPAIN Mumbai INDIA and the Kingdom of BAHRAIN Megger products are distributed in...

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