problem concerning voltage or current that results in a failure or misoperation of
customer equipment is a power quality problem.
Harmonic distortion in a power system is caused by nonlinear devices. Electronic
power converter loads constitute the most important class of nonlinear loads in a
power system. The switch mode power supplies in a number of single-phase
electronic equipment, such as personal computers, printers and copiers, have a very
high third-harmonic content in the current. Three-phase electronic power
converters, that is, dc/ac drives, however, do not generate third-harmonic currents.
Still, they can be significant sources of harmonics.
Power quality monitoring is an essential service that utilities can provide for their
industrial and key customers. Not only can a monitoring system provide
information about system disturbances and their possible causes, it can also detect
problem conditions throughout the system before they cause customer complaints,
equipment malfunctions and even equipment damage or failure. Power quality
problems are not limited to the utility side of the system. In fact, the majority of
power quality problems are localized within customer facilities. Thus, power
quality monitoring is not only an effective customer service strategy but also a way
to protect a utility's reputation for quality power and service.
CMHAI provides a method for monitoring the power quality by means of the
current waveform distortion. CMHAI provides a short-term 3-second average and a
long-term demand for TDD.
10.1.6 Signals
Table 643: CMHAI Input signals
Name
Type Default Description
I_A Signal 0 Phase A current
I_B Signal 0 Phase B current
I_C Signal 0 Phase C current
BLOCK BOOLEAN 0=False Block signal for all binary outputs
Table 644: CMHAI Output signals
Name
Type Description
ALARM BOOLEAN Alarm signal for TDD
1YHT530004D05 D Section 10
Power quality measurement functions
615 series 767
Technical Manual
To Next Page
Loading...
