CIRCUTOR QNA500 series - Manual (Page 33)

POWER QUALITY ANALYZER QNA500 8IO
QNA500 8IO Instruction manual 33 / 111
2. dV/dt detection (ramp method): This detection is achieved by comparing the measured wave
shape with an ideal wave shape. Each one of the 512 samples is compared to the previous
sample; when this value exceeds the value of the maximum ramp calculated for each point, the
system will consider that a transient or disturbance has been generated, depending on the
sensitivity selected by the user. The maximum ramp is the tangent calculated for each point of
the sine wave.
Rm = Vp * w/o
ϕ * trigger level
The following variables must be configured to record the wave shape:
• Nº pre-trigger cycles: Number of cycles registered before activating the record (1 to 10.
Default: 5)
• Nº. post-trigger cycles: Number of cycles registered after activating the record (1 to 50.
Default: 15)
• Trigger level (maximum ramp detection): Value that determines the transient detection
sensitivity level. The value entered must be from 1 to 100.
When the sensitivity value entered is very low, the analyzer will be very sensitive when
detecting transients. On the other hand, when the sensitivity value entered is very high, the
deformation of the signal must be greater for the analyzer to start detecting it.
• Maximum and minimum effective comparison values (RMS system): A maximum and
minimum voltage / current percentage must be programmed, when compared to the nominal
value.
The trigger is activated when the effective value of a cycle updated each semi-cycle exceeds
the maximum value or is under the minimum programmed value.
• Trigger variables: Variable or variables that will trip the trigger, in accordance with the
conditions described above. The trigger is activated by the first programmed variable that meets
the conditions when more than one variable is programmed.
The transient will be recorded in the COMTRADE format (according IEEE C37.111) and the data will
be saved in the WAVE directory of the memory. The waveform of the 4 voltage and current channels
(P1, P2, P3, N) will be stored for each disturbance detected. The memory record is stored at 204
samples per cycle.
The date of the last disturbance detected can be checked to guarantee the correct configuration of the
transient setup, adjusting the most adequate sensitivity degree for the installation.
The same configuration can be easily and quickly saved with CIRCUTOR's PC software.
8.5.- REMOVE FILES
Records can be deleted from the MULTIFIT system through the WEB server or the software supplied
by CIRCUTOR.
Refer to the specific section in this manual for more information about deleting records via the WEB
server. This action deletes all files associated to the measurements taken by the analyzer.