Measurement Procedure And Results Of "P-N" Mode - MARTINDALE VR2250 User Instruction Manual

6.4.2. Measurement procedure and results of "P-N" mode

1. Select P-N mode by means of the F1 key.
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-N 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 the point at which
the measurement is to be taken; as such impedances would be in parallel with
the line impedance to be measured.
START
5. Press the START key. The instrument starts the test.
STOP
The measurement in a 230V System, make a test current of 6A approx.
This may cause the tripping of magnetic protection switch with nominal
value lower than 10A. 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).
I
I
P
I1
B1 B2 B3 B4
Green
Black
CAUTION
LOOP
1.07
215A
FRQ=50.0HZ
VP-N=231V VP-PE=231V
P-N
FUNC Z2Ω
U
=
N
I
CC
Z
PN
Page 39 of 131
1
3
N
Red
B1
Instrument connection for P-N in a 400V three-
phase system
05.06.01
Value of phase to neutral line
impedance expressed in Ω.
Ω
Value of the phase to neutral
prospective short circuit
current expressed in Ampere
calculated according to the
following formula.
≤150
127 if V
meas
230 if 150V< V
VR2250
Black
Green
I1
B4
B2 B3
≤250
meas