HT instruments SPEED418 - Manual (Page 46)

400 Series
EN - 45
Formula used for calculating the prospective fault current:
PE
N
CC
Z
U
I

where: Z
PE
is the measured fault impedance
U
N
is the nominal phase-to-earth voltage
U
N
= 127V if V
P-PE meas
≤ 150V
U
N
= 230V or U
N
= 240V (§ 5.2.3) if V
P-PE meas
> 150V
7.
8. In TT systems, the impedance value measured by the instrument may only be referred
to the value of the total earth resistance. Therefore, in compliance with the
prescriptions of standard CEI64-8, the measured value may be taken as the value for
the system’s earth resistance
9.
The results displayed can be saved by pressing the SAVE key twice or the
SAVE
key and, subsequently, the ENTER key (§ 9.1)
6.6.1. Description of anomalous results
1. If the instrument detects an
impedance higher than the
full scale, at the and of the
test it displays the screen
reported here to the side and
gives a long acoustic signal
R a
>1999

- - - A
FRQ=50.0Hz
VP-N=230V
VP-Pe=230V
Impedance value higher than the full
scale
P-P and P-PE measured voltages
NOT OK
50V
UL
2. If the instrument detects an
impedance higher than the
limit value calculated as
U
LIM
/30mA (1666Ω@
U
LIM
=50V, 833Ω@U
LIM
=25V,
it displays the screen
reported here to the side and
gives a long acoustic signal
R a
1789

0 . 1 A
FRQ=50.0Hz
VP-N=228V
VP-Pe=228V
NOT OK
impedance value is higher than the
limit value calculated as U
LIM
/30mA
50V
UL
3.
The results displayed can be saved by pressing the SAVE key twice or the
SAVE
key and, subsequently, the ENTER key (§ 9.1)
4. If the instrument detects that
the phase and neutral leads
are inverted, the message
reported here to the side is
displayed. Rotate the shuko
plug or check the connection
of the single cables
R a
----

- - - A
FRQ=50.0Hz
VP-N=228V
VP-Pe= 1V
REVERSE P-N
The phase and neutral conductors
are inverted
50V
UL