10
GMC-I Messtechnik GmbH
8.1
Measuring Alternating Current with (Clip-On) Current
Transformers
8.1.1
Transformer Output mA / A
Attention!
!
If current transformers are operated without being
connected at the secondary side (e.g. as a result of
defective or missing cables, a blown device fuse or
incorrect connection), dangerously high voltages
may occur at the connector jacks. For this reason,
make sure that the measuring instrument’s current
path and the transformer’s secondary coil connected
to the instrument constitute an uninterrupted circuit,
and connect this circuit to the
⊥
and mA or A jacks.
Maximum allowable operating voltage is equal to the current
transformer’s nominal voltage. Do not forget to consider the
transformer’s transformation ratio and additional display error
when reading measured values.
8.1.2
Transformer Output V
Some transformers are equipped with a voltage output
(designation mV/A). The secondary terminals must thus be
connected to
⊥
and V.
9
Resistance Measurement
➭
Make sure that the device under test is voltage-free.
Interference voltages distort measurement results!
➭
Set the
rotary selector switch
to
Ω
.
➭
Connect the device under test as shown.
Zero Balancing
Δ
REL in the entire resistance measuring range
Cable and contact resistances can be eliminated during
resistance measurement by means of zero balancing:
➭
Plug the measuring cables into the instrument and
connect the free ends to each other.
➭
Press the
MAN / AUTO
and
HOLD
keys after selecting the
measuring range.
The instrument acknowledges zero balancing with an
acoustic signal and „0“ (+1 digit) and
Δ
REL appears at
the LCD, depending on the measuring range. The
resistance value measured at the moment the key is
pressed is automatically subtracted from all subsequent
measured values.
Zero balancing can be deleted:
–
by briefly pressing the
MAN / AUTO
key, which is
acknowledged by an acoustic signal,
–
by switching the instrument off.
~
R
x
~
R
x
1
3
Current
V~
05
.
00
V
Z13
B
2
0
.
5
k
Ω
Ω
R
x
Ω
:
600
Ω
…
40 M
Ω
Measuring Range:
+
–
R
x
0 V !
!
