ERICO EST401 ERITECH Clamp-on Ground Resistance Tester - Manual (Page 6)

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Description
The Ground Resistance Tester Model EST401 measures ground rod and small grid resistance
through any season, without the use of auxiliary ground rods. Clamp-on ground resistance
testers are used in multi-grounded systems without disconnecting the ground under test.
The EST401 simply clamps around the ground conductor or rod and measures the resistance
to ground. By performing measurements on intact ground systems, the user also verifies the
quality of the grounding connections and bonds. Resistance and continuity of grounding
loops around pads and buildings may also be measured.
The EST401 includes a current measurement function. The probe’s high sensitivity enables
measurement of leakage current flowing to ground or circulating in ground loops down to
1mA and neutral currents to 30Arms. This feature provides additional information which is
becoming vital as distribution ground networks carry higher levels of noise and harmonics
which affect power quality.
Battery life information is given at power-up and Auto-Off for power management.
Additional features are also displayed on the large LCD to ensure precise measurements.
The Buzzer and Auto-Off features may be disabled from the push-buttons at any time.
Product Construction
The EST401 body cases are built of Lexan ® for rugged use. The probe heads are encapsulat-
ed in a double-walled Lexan shell (or equivalent polycarbonate) for extra strength and are
reinforced at the body interfaces for enhanced field reliability. Overall construction and
mechanical design ratings such as drop test, shock and vibration, weatherproofing against
water projections, meet or exceed IEC (International Electrotechnical Commission)
standards. The products have also been designed to meet IEC 1010.
Jaw Design
The probe head, or jaw, is a key component in the measurement and overall product
performance. Considerable research and development were dedicated to ensuring its
performance, reliability and versatility.
The large jaw has an inner opening diameter of 1.25" (32 mm) permitting use on tight
ground conductors on poles and in manholes. The large opening accommodates not
only ground rods, but larger ground conductors (up to 1000 kcmil) typically found in
telecommunication or railroad applications.
The inner jaw is composed of two independent and individually shielded magnetic cores
permitting the injection of a test signal and accurate return signal measurement without
noise interference or cross talk common to separate probe instruments.
Thorough mechanical design, including small winglets, ensures repetitive jaw alignment
for accuracy and prevents undesirable insertions into the jaw spring assembly.
Body Design
The ergonomic body design permits one-handed operation. The guard provides additional
strength, and prevents the hand from slipping or coming into contact with conductors
under test. The Lexan (or equivalent polycarbonate) body construction provides strength.
The LCD lens cover may be easily replaced if scratched. The sealed push-buttons directly
access all test functions and are easily operated even with gloved hands.
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