Fluke 1742 User Manual page 37

This trigger is a general-purpose trigger that detects non-stationary
phenomena and is perfectly suitable for all kinds of disturbance
analysis and troubleshooting, because most of the power quality
problems result in a sudden change of the waveform. From the
recorded waveforms, in most cases the root-cause of distortions can
be identified: Switching of capacitor banks, commutation distortions,
and oscillations on the mains supply. In addition, ground shorts in the
medium voltage systems with their typical significant waveforms can
be identified. See Figure 13.
Maximum deviation V
Figure 13. Waveform Deviation
Parameters to configure:
•
Trigger on/off
•
Limit
The voltage threshold limit is the maximum deviation of the sample
magnitude of the actual cycle to the magnitude of the previous
cycle in % of nominal voltage.
Duration
Waveform of previous
cycle plus threshold limit
max
Waveform of previous
cycle minus threshold
limit
Recommendation of values depending on the required trigger
sensitivity:
Trigger 120V-System
Coarse 50%
Medium 20%
Fine 10%
Mains Signaling
Power distribution systems can carry control signals to remotely
switch on and off appliances (also known as ripple control). The
control signals are present only at the moments that a remote
appliance has to be controlled. The Mains Signaling trigger can
capture the occurrence (signal level) of control signals with 2 different
frequencies.
Parameters to configure:
•
Trigger on/off
•
Mains Signaling Voltage (MSV) frequency 1 and MSV frequency 2
in Hz
•
Frequency range is 100 Hz up to 3000 Hz
•
Limit
The voltage threshold limit value is defined as % of nominal
voltage. The value is typically in the range of 1 % to 5 %.
•
Recording time
The event triggers a 10/12 cycle recording of up to 120s.
Power Quality Logger
Instrument and Logging Setup
230V-System
25%
10%
5%
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