Fluke 43B Application Note

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Application Note

The power of

a waveform:

Expanded troubleshooting

options with the Fluke 345

Power Quality Clamp Meter

From the Fluke Digital Library @ www.fluke.com/library

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.

• An external power supply. While an exter-

nal power supply may not seem like a break-

through, 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.

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, Wash-

ington, served as a Beta test site for the Fluke

345 Clamp Meter. Before receiving the instru-

ment, 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 moni-

toring. 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 dis-

plays 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-

Meter® test tool, but it wouldn’t be as easy.

With the 345, I simply clamp on, set the func-

tion selector, and read both the current and the

voltage simultaneously. That really helps with

troubleshooting.”

• A clearer, more easily read display. Accord-

ing to Frank Healy, marketing manager for Fluke

power quality products, the improved, color dis-

play 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, har-

monics, and load.

2 Fluke Corporation The power of a waveform: Expanded troubleshooting options with the Fluke 345 Power Quality Clamp Meter

• 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 sam-

ple 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 mem-

ory, 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 power-

switching 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 can use the Fluke 345 to

measure high current on large cables, thanks to

the oversized jaws and current rating to 2,000 A

dc. Most clamp meters are limited to 1,000 A.

Electrical maintenance personnel can use the

Fluke 345 as a predictive maintenance tool. “With

this meter,” says Paul Swanson, “we could regu-

larly measure the secondary on our VFDs, establish

operational bench marks, and watch for condi-

tioning issues and other potential problems. We’d

establish the nominal operating parameters for

each drive’s output, like taking snapshots and stor-

ing them. Then, we’d go back every six months or

every year to see if there had been any noticeable

deterioration on the drive output waveform.”

Installers and maintainers of UPSs, VFDs,

and other switching loads will appreciate the

meter’s ability to measure both ac and dc, as well

as its low-pass filter. With a 345, an electrical

technician could go through a UPS checking the

input currents and inrush and look for harmonics.

Inside the UPS, the tech could check the dc link

and see the dc current prior to conversion into ac

on the opposite side.

Swanson explains that instead of one large,

centralized UPS, the King County Justice Center has

38 UPS units throughout the facility. They supply

backup power to the computerized security and

alarm systems and to various computer networks.

“We’ve spread out the UPSs,” Swanson explains.

“We have more points of potential failure, but

when one does fail it takes less out of our system.”

In monitoring a UPS, Swanson asks questions

that the Fluke 345 waveform display can answer:

What do my input and output look like? Do I have

harmonics? Is the UPS deteriorating in any way?

“Both on the input and the output, I can see if

anything’s being

pushed out onto

the lines,” Swan-

son says, “and

I can determine

whether the UPS

is actually doing

its job. I might be

able to do some of

that with a DMM,

but the findings

would be much

less clear.”

3 Fluke Corporation The power of a waveform: Expanded troubleshooting options with the Fluke 345 Power Quality Clamp Meter

Swanson, who has responsibility for a large

number of VFDs as well as all those UPSs, says

that the Fluke 345 would help him keep the

motor drives performing well and protect against

problems the drives might cause in the rest of the

facility. “The scope function on the 345 gives me

an opportunity to look at waveforms, which can

show me irregularities,” Swanson notes. “I could

detect any kind of distortion that may be coming

in on the power line or harmonics that could be

generated by the drive itself and going back onto

the grid. I need to know if the drive is creating

anything that could be detrimental to other equip-

ment.” With the low-pass filter, the 345 can accu-

rately read VFD output without interference.

The Fluke 345 is also useful for low-power

applications. “I’m often looking at the low-power

end of things,” Swanson acknowledges, “and

asking, ‘What noise is hitting my electronics?’ If

something affects my alarm system or my essential

computer systems, I’ve got problems. That’s my

primary concern.”

Adding new loads

Whenever a facility brings in new pieces of pro-

duction 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

Fluke Corporation

PO Box 9090, Everett, WA USA 98206

Fluke Europe B.V.

PO Box 1186, 5602 BD

Eindhoven, The Netherlands

For more information call:

In the U.S.A. (800) 443-5853 or

Fax (425) 446-5116

In Europe/M-East/Africa

+31 (0) 40 2675 200 or

Fax +31 (0) 40 2675 222

In Canada (800)-36-FLUKE or

Fax (905) 890-6866

From other countries +1 (425) 446-5500 or

Fax +1 (425) 446-5116

Web access: http://www.fluke.com

©2007 Fluke Corporation. All rights reserved.

Specifications subject to change without notice.

Printed in U.S.A. 4/2007 3034574 A-EN-N Rev A

Fluke. Keeping your world

up and running.®

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 pre-

dicted 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 wave-

forms 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 com-

mercial, industrial, and residential settings, when

standard instruments do not provide answers.