There are five vital measurements that could be causing problems in your electrical distribution system that you may be missing even with a True-rms digital multimeter. While the digital multimeter is a valuable and indispensable tool for the electrical professional, it does have limitations. A multimeter may be able to alert you to one of these five issues, but be prepared to use a power quality analyzer to dig in further and uncover these hidden potential problems.
Those measurements are:
Current flow in the system at a whole number multiple frequency of the fundamental frequency. The third harmonic current is current that flows at 180 Hz (the third harmonic of 60 Hz). While harmonic currents not only distort the fundamental 60 Hz sine waves, but excessive harmonics can also cause severe overheating and reduce motor efficiency. Once identified, filters can be installed to limit harmonic effects.
2. Total harmonic distortion (THD)
A measure of how much harmonic content there is in a waveform and should not exceed 5 % of voltage for reliable operation. If maximum acceptable THD is exceeded, locate and isolate the source of the harmonics, adding filters if needed.
A brief decrease (sag) or a brief increase (swell) in the nominal rms line voltage. Any such fluctuations in voltage can cause problems— from improper operation of electronic equipment to inadvertent relay operation.
4. Transients
Extremely short variations in voltages, often due to lightning strikes and load switching, and can cause equipment to shut down.
5. Power factor
A representation of the volt-amp loss in a system due to reactance. While poor power factor can mean utility penalty charges, the charges can often be corrected with the installation of power factor correction systems.
Selecting a power quality analyzer
The importance of investing in the right set of tools to monitor power quality issues, and prevent them in the future, can't be emphasized enough. Fluke offers an extensive range of excellent power meters and other power quality analyzers for troubleshooting, preventive maintenance, and long-term recording and analysis in industrial applications and utilities.
Fluke's range of power meters includes both single-phase and three-phase power quality analyzers for predictive maintenance, quality of service compliance testing and load studies. The three classifications are:
- Power quality analyzers and troubleshooters. Dedicated power and power quality clamp meters for frontline troubleshooting. Single-phase and three-phase power quality analyzers for predictive maintenance, quality of service compliance testing and load studies.
- Power quality loggers. Power loggers for characterizing power quality, conducting load studies and capturing hard-to-find voltage events over a user defined period of time.
- Power quality recorders. Advanced power quality recorders for capturing comprehensive details of power disturbances, trend analysis and Class-A "quality of service" compliance testing over a user defined period of time.
- High-precision power quality analyzers. Precision power quality tools designed to handle the most difficult waveforms. These testers pick up very low power factor or high-frequency waveforms, and can measure on single-phase, three-phase, or six-phase systems.