METREL MI 3290, Инструкция по эксплуатации

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MI 3290 Earth Analyser Terms and definitions
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Terms and definitions
For the purposes of this document and instrument Earth Analyser, the following definitions apply.
Index: Unit: Description:
Re
[Ω]
Earth resistance of complete system.
Ze
[Ω]
Earth impedance of complete system.
Rp
[Ω]
Auxiliary potential probe impedance.
Rc
[Ω]
Auxiliary current probe impedance.
Ie [A] System current or generator current.
f [Hz] Test frequency.
Ic [A] Iron clamp current.
Zsel
[Ω]
Earth impedance of measured branch.
Ztot
[Ω]
Total earth impedance of measured branches.
If1
[A] Flex clamp 1 current [F1
– terminal].
If2 [A] Flex clamp 2 current [F2
– terminal].
If3 [A] Flex clamp 3 current [F3
– terminal].
If4 [A] Flex clamp 4 current [F4
– terminal].
Zsel1
[Ω]
Earth impedance of measured branch [F1
– terminal].
Zsel2
[Ω]
Earth impedance of measured branch [F2
– terminal].
Zsel3
[Ω]
Earth impedance of measured branch [F3
– terminal].
Zsel4
[Ω]
Earth impedance of measured branch [F4
– terminal].
ρ [Ωm/ft] Specific earth resistance [resistivity].
R
[Ω]
Resistance [DC current].
Idc [A] DC current.
Z
[Ω]
Impedance [AC current].
Iac [A] AC current.
R [m/ft] Distance between E and auxiliary earth rod H.
r [m/ft] Distance between E and S probe.
ϕ [°]
Direction of potential measurement or angle
[0° - 360°].
Igen
[A] Generator current.
If_sum [A] Flex clamp current [If_sum = If1 + If2 + If3 + If4].
Uh [V] Uh voltage [H
– terminal].
Us [V] Us voltage [S
– terminal].
Ues [V] Ues voltage [ES
– terminal].
Ig_w
[A] Overhead ground wire current [Ig_w = Igen - If_sum].
R
[Ω]
Complex number [real number].
X
[Ω]
Complex number [Imaginary number].
φ [°]
Phase angle between u and i.
Zp
[Ω]
Impulse impedance [is defined as the peak voltage divided by the peak current].
Up [V] Peak voltage.
Ip [A] Peak current.
d [m/ft] Sum of steps or total distance [d =
Step Size × (Number of measurements - 1)].
Step Size [m/ft] Distance between neighbouring measurement points [fixed value].
Ifault [A] Maximum expected fault current.
Designation of the terminals:
 E - terminal for the earth electrode;
 ES - terminal for the probe placed nearest to the earth electrode;
 S - terminal for a probe;
 H - terminal for the auxiliary earth electrode.
Notes (acc.to EN 50522-2010):

Resistance to earth, R
E
- real part of the impedance to earth.

Impedance to earth, Z
E
- impedance at a given frequency between a specified point in a
system or in an installation or in equipment and reference earth.
The impedance to earth is determined by the directly connected earth electrodes and also by connected
overhead earth wires and wires buried in earth of overhead lines, by connected cables with earth electrode
effect and by other earthing systems which are conductively connected to the relevant earthing system by
conductive cable sheaths, shields, PEN conductors or in another way.