Measurement Procedure And Results Of " R; A " Mode - MARTINDALE VR2250 User Instruction Manual

6.4.5. Measurement procedure and results of " R

1. Select R
A
2. Connect the Red, Green and Black connectors of the three-terminal mains cable or
of the split cables to the corresponding input terminals of the instrument B1, B3, B4.
Red
Instrument connection for P-PE test in a 230V
single-phase System
3. Connect the mains plug into a 230V 50Hz socket or the crocodiles to the
conductors of the three-phase system (see previous pictures).
4. If possible disconnect all low impedance loads downstream of the point at which
the measurement is to be taken; as such impedance would be in parallel with
the line impedance to be measured.
5. The key F4 permits to select one of the following limit values for the contact
voltage (which can be shown cyclically when pressing the key):
50V (default)
25V.
6. Press the START key once to execute a test with "0°" test current.
START
STOP
Press the START key twice to execute a test with "180°" test current.
The R
A
tripping of 10mA. If necessary perform the test upstream of the switch. Never
disconnect the test leads when the message "MEASURING" is displayed.
At the end of the test
the instrument emits a
double sound signal
indicating that the test
is correctly
terminated and
displays the values
alongside.
Working mode
Formula for calculation of prospective short circuit current:
Where U = Nominal phase to neutral voltage =
N
This result can be stored pressing the SAVE key twice (according to paragraph 9.1).
mode by means of the F1 key.
I
I
P
I1
B1 B2 B3 B4
Black
Green
measurement make a test current of 15mA. This may cause the
LOOP
2
115A
Freq=50.0HZ
VP-N=231V
R
A
FUNC
Page 43 of 131
" mode
A
1
3
N
Black
Instrument connection for P-PE in a 400V three-
phase system
or
CAUTION
05.06.01
Value of phase to Earth
Resistance expressed in Ω.
Ω
Effective value of the phase
to Earth prospective short
circuit current expressed in
Amps calculated according to
Vp-PE=231V
the following formula.
=
I
CC
≤ 150
127 if V
meas
230 if 150V< V
VR2250
Red
Green
I1
B1 B2 B3 B4
U
N
Z
PE
≤ 250
meas