METREL Eurotest 61557 User manual

Eurotest 61557
MI 2086
User Manual
Version 4.2, Code no. 20 750 719

MI 2086 Eurotest Measurement instructions
27
3.5. Earth Resistance (internal generator)
The Eurotest 61557 test instrument is able to carry out Earth Resistance
measurement using tree different methods. The appropriate one is to be selected by
the operator on basis of concrete earthing system to be tested.
For additional general information concerning Earth Resistance measurement, refer to
enclosed handbook Measurements on electric installations in practice and
theory.
How to carry out Earth Resistance measurement using
standard four-lead test method?
Step 1
♦Set function switch to ρREposition, “Earth Resistance” or “Earth Resistivity”
menu will be displayed.
♦Select Earth Resistance function (standard four-lead method) by using the
FUNC (F1) key. Earth Resistance function (standard four-lead method) is
selected, when R EARTH is displayed; see the figure below.
Fig. 23. Earth Resistance initial menu
Step 2
♦Set High limit Earth Resistance value. Later will test results be compared with
the set limit value and, if higher, they will be equipped with “!”mark and Result
over limit message.
How to set the high limit value?
♦Press the Hlim (F2) key, to enter “Limit value adjustment mode”, the following
menu will be displayed:
Rc... Resistance of current probe.
Rp... Resistance of potential probe.

MI 2086 Eurotest Measurement instructions
28
Fig. 24. Limit adjustment menu and table of presettable limit values
♦Value between 1 Ωand 5000 Ω, according to the table above may be selected
by using the ↑(F2) and ↓(F3) keys. If test result is not to be compared with set
limit value at all, then press the Off (F4) key. Set limit value (displayed on top
display line) will be substituted with ∗Ω mark. The Off key will alter to On,
enabling the operator to turn the limit value ON again and vice versa.
♦Press the Back (F1) key after setting limit value, to return to “Earth Resistance
initial menu” (see the figure 19.).
Step 3
♦Connect test leads to the instrument and to tested object according to the
figures below (press the HELP key for basic connection information).
Fig. 25. Connection of optional Earth Test Set – 20 m (Order No. S 2001)
Range / discrete
value (Ω) Step (Ω)
1 – 100 1
166, 250, 500,
833, 1666,
2500, 5000
⁄
MPEC
Rc Rp R E
d
Option S 2001
>5d
E
ES
HS
b
lue
black
g
reen
r
e
d

MI 2086 Eurotest Measurement instructions
29
Fig. 26. Connection of optional Earth Test Set – 50 m (Order No. S 2002)
Step 4
♦Press the START key and keep it pressed, until result is stabilised, then release
the key. Test result is displayed; see an example of the result on figure below.
Rc
Rp k k
64.8 1.52
2.63
Fig. 27. Example of Earth Resistance test result
♦Store displayed result for documentation purpose; see instructions how to store it
in chapter 4.3. Storing test results.
Notes!
♦In case of present external voltage higher than 20 V a.c./d.c. between H and E
or ES and S test terminals, the Earth Resistance measurement will not be
carried out after pressing START key, but the voltage will be displayed,
equipped with “!” mark and Input voltage > 20 V message! Beep warning sound
will be affected too!
♦If resistance of current or potential probe is too high (>(4 k Ω+ 100 RE) or >50
kΩ, whichever is lower), test result will be equipped with “!” mark and
Pote. spike Rp > xxx Ω/ Curr. spike Rc > xxx Ωmessage. The value xxx is
currently calculated (for each displayed result) on basis of displayed result!
♦If test result is out of measurement range (open test leads), >20 k Ωmessage
will be displayed!
Both resistances, Rc and Rp are
measured and displayed
continuously.
E
ES
HS
b
lue
black
green
r
e
d
R3 E
R4 E
MPEC
d
>5d
Option S 2002
R E1
R2 E
RpRc