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SGT-600 USER’S MANUAL
REV 1
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1.0 INTRODUCTION
1.1
General Description and Features
The SGT-600 is a 600 ampere micro-ohm meter designed for testing utility safety ground cables.
The SGT-600 features microprocessor-controlled highly accurate measuring of very low
resistances ranging from 1 micro-ohm to 450 milliohms. The SGT-600 is field-portable, rugged,
and easily operated by first-time users with a minimum training. It features a 44-key
"QWERTY"-style keypad for entering test parameters and controlling the unit and a back-lit LCD
screen (128 x 64 pixels) for displaying menus, measured resistance values, and related
identifying data. The SGT-600 also features a built-in thermal printer used to print test data on
2.5" wide thermal paper. Operating the unit requires little more than connecting the safety
leads to the SGT-600 terminals, enter the test cable size, cable length, cable temperature, and
the test current. The SGT-600 will measure the cable resistance and compare this reading
against the maximum allowable resistance value (defined by ASTM F2249). The resistance
reading along with the Pass or Fail results can be printed using the built-in thermal printer.
Test current is selectable from 10 to 600 amperes. The SGT-600 can also store 100 test records
in internal FLASH EEPROM memory. Stored resistance measurements and related data can be
recalled at a later time for review and printing and can also be transferred to a USB Flash drive
using the unit's built-in Flash drive port.
Windows®-based analysis software is provided with each unit. The software can be used to
retrieve test records from the unit's internal memory or from a computer hard drive, analyze
test results, and print test results on a desktop printer. Test results can also be exported to PDF,
Excel and XML formats.
The SGT-600 measures the total resistance value of the cable under test and then compares it
to the calculated value to determine the Pass or Fail result. In order to calculate the total
resistance value, the user is first prompted for the cable size, cable length, and cable
temperature. Total resistance (
Rm
) is calculated in accordance with the ASTM F2249-03
standard using the formula below:
Rm = 1.05 RL + 2Y = 1.05 RL + 320 µ
Ω
*
Where:
Y
= Resistance of clamps, ferrule, and portions of the cable inside the ferrule, in milliohms*
L
= Cable length in feet (ferrule to ferrule measurement to the nearest inch)
R = Cable resistance, in milliohms/foot
* NOTE:
The clamp and ferrule resistance value of 160 µ
Ω
is used per the ASTM-F2249-03
standard.
