Determining The Leakage Inductance; 4-Wire Smd Test Adapter R&S®Hz188 - Hameg R&S HM8118 Benutzerhandbuch

Fig. 8.9: Measuring the mutual inductance
The R&S®HM8118 calculates a „virtual" impedance
Z = V / I . V is the secondary voltage, I
s p s
current (all complex values). The mutual inductance is cal-
culated using the mutual inductance definition:
V = R * I + L dI /dt + M dI
s s s s s
If no current is applied to the secondary winding (I
the following is true:
V = M dIp/dt or M = Im{Z}/w.
s
In this case, the value for M can also be negative. It is pos-
sible to use a BIAS current if necessary. However, BIAS
is not used to improve the accuracy. Some coils may be
subjected to a strong bias current BIAS. In this case, the
measurement must be performed under the same condi-
tions as they are to be used for the circuit.

8.3.4 Determining the Leakage Inductance

The short circuit principle is applied to determine the
leakage inductance for the R&S®HM8118 bridge. The wi-
ring to determine the leakage inductance does not differ
from a conventional inductance measurement. The com-
ponent / transformer is connected to the instrument via
BNC connectors on the R&S®HM8118 instrument front pa-
H CUR
nel. The R&S®HZ186 is not mandatory for this purpose.
You can also use the included standard cable which is sui-
H POT
table for inductance measurements. Before determining
the leakage inductance, it is recommended to first perform L POT
a conventional inductance measurement of the primary
transformer winding. In this case, the secondary side re-
L CUR
mains open (see fig. 8.10).
H CUR
H POT
C
L POT
L CUR
Fig. 8.10: Primary inductance measurement
is the primary
p
/dt
p
s
primary secondary
SHORT
primary secondary
R
OPEN
L
Contrary to a conventional inductance measurement, de-
termining the leakage inductance requires the secondary
transformer side to be short-circuited (see fig. 8.11). If the
secondary side is short-circuited, the measured values of
the primary side correspond to the leakage inductance.
H CUR
H POT
L POT
L CUR
Abb. 8.11: Leakage inductance measurement
H CUR
8.4 4-Wire SMD Test Adapter R&S®HZ188
H POT
= 0),
L POT
L CUR
Fig. 8.12: 4-wire-SMD test adapter R&S®HZ188
The SMD test adapter R&S®HZ188 is suitable to qualify
SMD components. The test adapter converts the confi-
guration of a 4-wire measurement to a 2-wire measure-
ment. Due to its net weight, it is recommended to mount
the measurement adapter and bridge to a flat surface (e.g.
a table). The test adapter is directly connected to the front
panel BNC connectors of the bridge via the four BNC so-
ckets. For the measurement, insert the SMD component to
be measured with its connectors between the two provi-
ded contact pins (measurement contacts). This equipment
is included in delivery.
Technical Data R&S®HZ188
Function:
Measurable components:
Frequency range:
Maximum voltage:
Connectors:
Safety standards:
Environmental conditions:
Operating temperature:
Temperature limits:
Weight:
Measuring Equipment
primary secondary
primary secondary
R
L
C
Test adapter to operate (via 4-wire connec-
tion) with LCR bridge HM8118
SMD resistances, coils or capacitators
20 Hz to 200 kHz
± 40 V maximum value (AC+DC)
BNC sockets (4), measurement contacts (2)
EN61010-1; IEC61010-1;
EN61010-031; IEC61010-031
Contamination Class 2, internal use
+5 °C to +40 °C
-20 °C to +70 °C
approximately 300 g
SHORT
OPEN
63