Megger DET3, DET4, DET4TC, DET4TCR+Kit, DET4TC+Kit User Manual

NEW PRODUCT LAUNCH

Sales guide

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The latest additions to the DET Earth testing range.

Providing a solution to every

earth testing challenge

Megger Limited PWS / Nov 06
DET4TC/R launch

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Table of Contents

PRODUCT FAMILY .......................................................................3

DET4TC/R Selection Chart........................................................... 3

NEW – Professional Earth Testing Kit........................................ 4

THIS PRODUCT IS USED FOR? ..................................................5

WHY?............................................................................................. 5

THIS PRODUCT IS USED BY? ..................................................... 6

TECHNICAL OVERVIEW ..............................................................7

Principle of Operation .................................................................. 8

FEATURES, ADVANTAGES AND BENEFITS ........................... 10

ORDERING INFORMATION........................................................ 11

COMPETITOR ANALYSIS ..........................................................11

DET4TC/R Verses Fluke 1623 ...............................................................................12

DET4TC/R Verses Fluke 1625 ...............................................................................13

DET4TC/R verses Metrel M2124C.........................................................................14

Appendix A.................................................................................. 15

Application Guide .................................................................................15

The “ART” of earth electrode testing ............................................15

Just a little aside ..........................................................................................16

Megger gets down to earth with “ART”...............................................16

Don’t underestimate the power of “ART” ...........................................18

The problem with Spheres of Influence..............................................19

We all like “ART” but sometimes it’s misunderstood ....................21

Some resistance to ART ..........................................................................22

The Best Application of “ART” ...............................................................22

“STAKELESS” Earth Electrode Testing .....................................23

Incorrect use of Stakeless testing.........................................................25

The Best Application of “Stakeless” testing......................................26

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DET4TC/R Launch

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PRODUCT FAMILY

The new products are additions to the DET3 and 4 contractor series of earth testers,
launched about a year ago.

The instruments utilises the same rubber armoured, IP54 rated case as the DET3
and is supplied in a tough blow moulded case together with test leads and spikes.

The structure of the new instruments is as follows:

DET4TC 2, 3 & 4 pole earth testers with ART and Stakeless testing

capability

DET4TCR 2, 3 & 4 pole, rechargeable, earth testers with ART and

Stakeless testing capability.

DET4TC+Kit 2, 3 & 4 pole earth testers with ART and Stakeless testing,

complete with ICLAMP and VCLAMP.

DET4TCR+Kit 2, 3 & 4 pole, rechargeable, earth testers with ART and

Stakeless testing, complete with ICLAMP and VCLAMP.

The new DET4 range replaces the complete DET5/4 range, which has an intended
obsolescence date of 30

The complete contractor series of Earth testers can now be summarised by the
following chart:

DET4TC/R Selection Chart

Feature Sub-feature DET3TADET3TD DET3TC DET4TD DET4TC DET4TCR

Display Analog

Earth Tests 2 Pole

Earth Resistance Range 0.01 to 2kΩ

Earth Voltage Range 0-100V
Earth Current Range 0.5mA to 19.9A
Supply Alkaline batteries

Digital
Back light

3 Pole (Fall of potential)
4 Pole (Soil resistivity)
Selective (ART) capability
Stakeless (2 clamps)

0.01 to 20kΩ

Rechargeable batteries

Where does the name come from?

D E T 4T C R

Digital Earth Tester 4 Terminal Clamp Rechargeable

th

June 2007.

✔

✔✔✔✔✔

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✔✔✔✔✔✔

✔✔✔

✔✔✔

✔✔
✔✔✔✔

✔✔
✔✔✔✔✔✔

✔✔✔

✔✔✔✔✔

✔

Megger Limited PWS / Nov 06
DET4TC/R Launch

NEW – Professional Earth Testing Kit

To complement the launch of the new DET4TC/R a new Professional Earth Testing
Kit will be available shortly.

4

The new kit is innovative, high quality and comes supplied in a tough hard carry case
similar to the instrument carry case.

The kit consist of the following:

• Four twist in auger style test spikes

• Four test leads (2 x 50m, 2 x 30m)

o Supplied on four reels with test lead wind in while mounted on test

spike feature.

o Reels have innovative test lead brushing feature to clean while

winding in.

• Tape measure

Kit part number: 6320-245

Megger Limited PWS / Nov 06
DET4TC/R Launch

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THIS PRODUCT (DET4TC/R) IS USED FOR?

This product is used for both soil resistivity testing (4 pole) and earth electrode (2 and
3 pole) testing. Methods such as ART allow earth electrodes to be tested without
disconnection. The addition of Stakeless testing will allow testing of electrode where
the use of test stakes is impractical.

WHY?

• Soil resistivity testing. (4 pole)

o Used to locate the best lowest resistance location for a new earth

system.

o Obtain earth resistance values required to design the earth system
o Geophysics – locating changes in geology

• Earth Electrode testing (2, 3 pole)

o Earth electrode / system resistance must be low and reliable. Why?

• To ensure enough current to flow in fault conditions to ensure
the circuits’ protective device trips out in time. Failure to trip or
trip too slowly can result in expensive damage to equipment,
fire or serious injury.

• Lightning strike protection.

• Improve equipment performance by reducing noise levels.

• Static electricity dissipation.

• Prevent dangerously high step or contact voltages present

during fault or high load conditions, another safety issue.

o Earth systems require testing both immediately after installation, and

at regular intervals thereafter as part of a maintenance program.

• ART – Attached Rod Technique

o This method is an additional feature used when performing the

standard 3 pole method when testing earth electrode resistance.

o The main problem associated with testing an electrode resistance is

the requirement to disconnect it. This is because the test current from
the instrument will flow, not just down the electrode being tested, but
also through any other parallel paths. E.g. other electrodes in the
system or back through the building earth.

• ART uses a clamp to measure only the current flowing down
the electrode being tested; the instrument then uses this
measurement to calculate the resistance of electrode.

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DET4TC/R Launch

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• Stakeless Test – Look no test spikes!

o Although the 3-pole method is the traditional method of test earth

electrode resistance, it relies on driving auxiliary test spikes into the
ground, which is not always practical. Imagine trying to drive spikes in
inner city concrete jungles, and locations such as cable cellars
beneath sub stations.

o Another ideal application for this test is measuring electrode

resistance on lightning protection system on buildings.

• The stakeless method utilises two clamps. One to induces
current into the circuit the other the measure the resulting
amount.

• The measurement taken is the resistance of a loop, including
that of the electrode under test.

• The reading will not directly compare to the 3-pole method due
to the additional elements in the reading. However the
readings will always be optimistic and should be repeatable,
ideal for monitoring the earth electrode condition over time.

• Stakeless measurements made in 4-pole mode allow all test
lead resistances to be ignored.

In summary, with the addition of ART and Stakeless testing, DET4TC/R is an
excellent replacement for the DET5/4. The DET4TC/R provides real additional
benefits to the customer in terms of ease of use and the ability to take measurements
in situations the DET5/4 cannot.

Provided with this sales guide in appendix A, is a applications note giving detailed
information on how to use ART and Stakeless testing. This will give valuable
assistance to customers, allowing them to fully understand and get the most from
these test methods.
Further, more detailed information on earth testing may be found on the Megger
Earth/ground micro site. http://www.megger.com/us/story/Index.php?ID=125

THIS PRODUCT IS USED BY?

• Electrical contractors,

• Utilities, Maintenance

• Railways

• Repair Organisations (Industrials),

• Telecoms and Datacoms installers.

• Specialist grounding/earthing companies and consultants.

• Petro-chemical companies

• Service providers

Megger Limited PWS / Nov 06
DET4TC/R Launch

TECHNICAL OVERVIEW

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DET4TC/R Launch

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DET4TCR

The instrument and display layout are identical with the exception of the 12V input for
battery charging.

Principle of Operation

The principal of operation is fully described in the User Guide, a copy of which has
been provided as part of the launch pack. However since the DET4TCR is replacing
the DET5/4, just the pertinent parts covering the additional ART and Stakeless
capabilities have been reproduced in this document.

Principle of operation (three-terminal resistance measurement using
ART)

The classic three-terminal test method has a disadvantage, namely that the electrode
under test must be disconnected from the system it is supposed to protect in the
event of a power system fault. The reason for this is that the injected test current will
take all possible routes to ground and not all of it will necessarily flow through the
electrode under test. In this case, the instrument will make a reading
of the entire earthing network, not just the individual electrode.
By using a current transducer (the Megger ICLAMP) to measure the current flowing
through the electrode under test as a fraction of the total test current injected, the
instrument can determine the individual resistance. This arrangement is shown in
Figure 7.

Megger Limited PWS / Nov 06
DET4TC/R Launch