Electricians are discovering that the new Fluke 345 goes beyond simply monitoring voltage or current. It displays waveforms and harmonics, performs power measurements for power-factor evaluations, measures inrush current, and logs data over time for later analysis.
Like other test and measurement equipment from Fluke Corporation, the Fluke 345 Power Quality Clamp Meter was designed based on input from electricians, electrical contractors, maintenance personnel, and other test tool users.
What customers requested
- More capabilities in a single meter. The Regional Justice Center for King County, Washington, served as a Beta test site for the Fluke 345 Clamp Meter. Before receiving the instrument, Paul Swanson, a lead electrician at the site, used a digital multimeter (DMM) and a clamp meter to do his job. He says, "The 345 adds a visual representation of what I'm monitoring. When I use a DMM, I might be able to detect a little variation in voltage or current, but there's no indication of what's causing it." By contrast, the Fluke 345 simultaneously displays readings and waveforms for voltage and current. "You can see things with the 345 you can't see with a DMM," Swanson observes. "I probably could log the same data with a Scope-MeterÃ‚Â® test tool, but it wouldn't be as easy. With the 345, I simply clamp on, set the function selector, and read both the current and the voltage simultaneously. That really helps with troubleshooting."
- A clearer, more easily read display. According to Frank Healy, marketing manager for Fluke power quality products, the improved, color display is a direct result of customer feedback. The clarity and color allow users to distinctly view multi-channel information. In waveform mode, for example, current and voltage waveforms are separate and clearly defined. The color also improves other current and voltage views, harmonics, and load.
- An external power supply. While an external power supply may not seem like a breakthrough, engineering a tool to be both CAT IV 600 V safety rated and externally powered is no small feat. But why an external power supply?
- Long-term logging capability. Strictly battery-powered instruments can't perform long-term sampling. The batteries run down. But customers needed long-term sampling to track intermittent faults and other hidden power quality problems. When the Fluke 345 is connected to an external power source, sampling time is limited only by the memory capacity of the instrument and the sampling rate.
- The ability to monitor both ac and dc loads. When it comes to long-term data logging, users of earlier meters said they needed to monitor single-phase ac and dc loads. Healy notes that most loggers only read ac. Some are dc-only loggers. By contrast, the Fluke 345 offers ac current monitoring up to 1400 A and dc up to 2,000 A.
The dual-current capability could only be engineered into a clamp meter. Healy explains: "There is no technology available for measuring dc current using a flexible probe. So, the clamp itself is a Hall-effect sensor, and it can measure ac and dc current simultaneously. By contrast, a Rogowski-type device can only measure ac. We wanted one self-contained tool that didn't need extra leads to measure current."
- A large, flexible memory configuration. The Fluke 345 has three distinct memory locations, where three separate logs can be stored at the same time. Using this feature, an electrician can go into the field and make a log of, say, twenty minutes and then hour-long logs in two other places, all without returning to the office to download data.
Alternatively, if the electrician needs to sample data for a longer period, the logger can be left at a single location for an extended period of time. There, it can store data in all three memory areas during the sampling period. According to Healy, an electrician could record for hundreds of days, depending upon the averaging period (sample frequency). The data is stored in memory, and, following downloading to a PC via USB, can be analyzed using the Power Log software shipped with the instrument.
- The ability to easily measure inrush. When a motor starts, some electrical systems may experience a surge in load demand called inrush. It can be enough to trip breakers, dim the lights, and cause other anomalies. To log inrush data on the Fluke 345, says Healy, "just set the trigger level for current and put the instrument in pulse. Then, when the meter sees a high level of current, it finds it and captures its characteristics."
Swanson ties the easy monitoring of powerswitching events - the rapid adding or removing of loads from a system to the Fluke 345's versatile data storage capabilities. "I was happy to discover that regardless of the sample frequency, the instrument records peak, low, and average readings - all three. If I take the time to do the math, I can even figure out the duration of an event."
Who's the Fluke 345 designed for?
While the Fluke 345 Power Quality Clamp Meter was designed with many users in mind, Frank Healy says utility trouble-shooters and field install/service techs will find it especially useful.
- Utility personnel
- Electrical maintenance personnel
- Installers and maintainers
Adding new loads
Whenever a facility brings in new pieces of production or process equipment, that adds new loads to existing electrical supply systems. Because the Fluke 345 can take power measurements (watts, VA, VAR, volts, amps, and power factor) in both single-phase and balanced three-phase power systems, the instrument allows users to determine circuit loading and thereby judge whether it is safe to add more load or if a new circuit is required.
Then, while connecting the new equipment, the electricians can use the Fluke 345 to measure the loading of the equipment as it is installed. Finally, they can check post-installation harmonics to see whether the new equipment is operating as predicted or if it is producing new, possibly harmful harmonics or contributing to other problems. For initial installations of new plant and equipment, plant personnel will want to look at current waveforms and voltage waveforms to how the installed equipment is affecting supply components and other equipment.
Power measurements are also essential for identifying and correcting low power factor, a cause of high utility bills. In fact, the Fluke 345 offers the ease of use, portability and flexibility needed to solve most electrical problems in commercial, industrial, and residential settings, when standard instruments do not provide answers.