Atec Hipotronics-DDX9121B - Manual (Page 3)

Haefely has a policy of continuous product improvement. Therefore we reserve the right to change design and specification without notice . LL_DDX9121b-1_1311_SG_1.doc – 3/6
SELECTABLE MEASURING BAND
A wide band detector measures and displays the composite
of all the signals and interference present within its
bandwidth. Any PD activity will be difficult to differentiate
from the noise floor. However, there could be a number of
areas in the frequency spectrum where PD signals is at a
much higher level than the unwanted interference. Defining
a measuring band within these optimized areas will result
in a higher measuring sensitivity and therefore a lower
ground noise level.
The IEC 60270 defines some limits in regards to the
measuring band as following.
30kHz < f
1
< 100kHz
f
2
< 500kHz
100kHz<  f <400kHz
0
2 0
4 0
6 0
8 0
10 0
12 0
1 10 100 1000 10000
Frequency (kHz)
f
1
f
2
The DDX9121b is equipped with a frequency spectrum
analyzer, where the operator can easily select the optimized
measuring band based on the measured ground noise.
EASY TO CONFIGURE
The DDX9121b measuring system is based on passive
coupling impedances without batteries. In addition the wide
range of the input voltage (140 V) makes the device
connection easier than ever.
Just connect the coupling impedance (AKV9310) to your
coupling capacitor, plug the DDX9121 to the net and
connect through a normal or fiber optic (optional) LAN
cable to the computer. Connect the included twin BNC
cable between the DDX9121b and the impedance and start
measuring PD.
SIMULTANEOUS PD AND RIV READINGS
(OPTIONAL)
The DDX 9121b measures RIV according to ANSI and
NEMA 107-1987, therefore the replacement of outdated RIV
measuring instruments is straight forward without
differences in measurement results.
Both RIV voltage (mV, According to NEMA 107-1987) and
Partial discharge (pC, according IEC 60270) measurements
are done simultaneously, therefore both are performed in a
single test without overstressing the test object. In
addition, real time comparison between PD level and RIV is
possible.
PD UNDER DC (OPTIONAL)
While measuring PD on DC test voltage, an
accurate recording of each PD event is of maximum
importance, as the accepting/rejecting value will
take into consideration not only the magnitude of
the pulses, also the number of pulses during the
test duration. The DDX9121b is a trusty device
while doing this particular test.
0
2 0
4 0
6 0
8 0
10 0
12 0
1 10 100 1000 10000
Partial discharge FFT RF broadcast FFT Tyristor pulse FFT
Optimized measuring band
f(khz)