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Introduction
played. The value should be appr. 280 µH. As shown in Fig.
3.2, the phase angle of an inductor must be in the range
of + 45 to 90°. In order to prove this, leave the automatic
mode by pushing the button „Z-Θ
played will be appr. +70° and depends on the measuring
frequency set.
For comparison: the phase angle of the capacitor meas-
ured before is appr. -87° at 50 Hz.
3.4
Measurement of a resistor
Disconnect the choke and connect the 100 kΩ resistor sup-
plied. As the instrument was previously set manually to the
function Z-Θ, the value of its impedance can be directly
read (appr. 100 kΩ). As decribed on the page before, an
ideal resistor has no capacitive or inductive components.
Hence the phase resp. loss angle of the component con-
nected is close to zero degrees.
The R&S®HM8118, upon connection of the resistor, auto-
matically changed the internal equivalent circuit from se-
ries connection SER to parallel connection PAR (LED push-
buttons
and
). If the automatic selection of the equiv-
15
16
alent circuit was chosen (pushbutton AUTO
measuring bridge will automatically select the equivalent
circuit which, depending on the component connected,
is best suited to yield a precise measurement result. The
equivalent circuit represents the measurement circuit.
Usually, components with a low impedance (capacitors,
chokes) will be measured using the series connection
equivalent circuit while components with a high impe-
dance (e.g. resistors) will be measured using the parallel
equivalent circuit.
46
. The phase angle dis-
39
), the LCR
14
4 First-Time Ope-
ration
4.1
Connecting the instrument
Fig. 4.1: Power Input
Prior to connecting the instrument to the mains, check
whether the mains voltage conforms to the mains voltage
range specified on the rear panel. This instrument has a
wide-range power supply and hence requires no manual
setting of the mains voltage.
The fuse holder of the BIAS FUSE
input, is accessible on the rear panel. Prior to exchanging a
fuse the instrument must be disconnected from the mains.
Then the fuse holder may be removed with a suitable
screw driver, using the slot provided. Afterwards the fuse
can be removed from the holder and exchanged. The hol-
der is spring-loaded and has to be pushed in and turned.
It is prohibited to use „repaired" fuses or to short-circuit
the fuse. Any damages incurred by such manipulations will
void the warranty. The fuse may only be exchanged by this
type:
Fuse with ceramic body, filled with fire extinguishing
material:
Size 6.3 x 32 mm; 400 V
AC
(alternatively DIN 41 571, p. 3), (F) 0,5 A
Fig. 4.2: Rear panel with fuse
4.2
Turning on the instrument
Prior to operating the instrument for the first time, ple-
ase be sure to observe the safety instructions mentioned
previously!
The LCR bridge is switched on by using the power switch
. Once all keys have briefly been illuminated, the bridge
1
can be operated via keys and the knob on the front pa-
nel. If the keys and the display do not light up, either the
mains voltage is switched off or the internal input line fu-
ses are defective. The current measurement results are
, i.e. the external BIAS
45
, C; IEC 127, Bl. III; DIN 41 662
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