Fluke 374, 375, 376 Operating Manual

Users Manual

374/375/376

Clamp Meter

PN 3608883
July 2010

© 2010 Fluke Corporation. All rights reserved. Printed in China. Specifications are subject to change without notice.
All product names are trademarks of their respective companies.

LIMITED WARRANTY AND LIMITATION OF LIABILITY

This Fluke product will be free from defects in material and workmanship for three
years from the date of purchase. This warranty does not cover fuses, disposable
batteries, or damage from accident, neglect, misuse, alteration, contamination, or
abnormal conditions of operation or handling. Resellers are not authorized to extend
any other warranty on Fluke’s behalf. To obtain service during the warranty period,
contact your nearest Fluke authorized service center to obtain return authorization
information, then send the product to that Service Center with a description of the
problem.

THIS WARRANTY IS YOUR ONLY REMEDY. NO OTHER WARRANTIES, SUCH AS
FITNESS FOR A PARTICULAR PURPOSE, ARE EXPRESSED OR IMPLIED. FLUKE
IS NOT LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR
CONSEQUENTIAL DAMAGES OR LOSSES, ARISING FROM ANY CAUSE OR
THEORY. Since some states or countries do not allow the exclusion or limitation of an
implied warranty or of incidental or consequential damages, this limitation of liability
may not apply to you.

Fluke Corporation
P.O. Box 9090
Everett, WA 98206-9090
U.S.A.

11/99

Fluke Europe B.V.
P.O. Box 1186
5602 BD Eindhoven
The Netherlands

Table of Contents

Title Page

Introduction................................................................................................................. 1

How to Contact Fluke ................................................................................................. 2

Safety Information ...................................................................................................... 3

The Meter ................................................................................................................... 9

Specifications ............................................................................................................. 19

Electrical Specifications.......................................................................................... 19

Mechanical Specifications ...................................................................................... 26

Environmental Specifications ................................................................................. 27

i

374, 375, 376

Users Manual

ii

Introduction

XWWarning

Read "Safety Information" before you use the Meter.

The Fluke 374, 375, and 376 (the Meter) measure true-rms ac current and voltage, dc current
and voltage, inrush current, resistance, and capacitance. The 375 and 376 also measure
frequency and dc millivolts. The detachable iFlex (Flexible Current Probe) that is included with the
376 (optional with the 374 and 375) expands the measurement range to 2500 A ac. The Flexible
Current Probe provides increased display flexibility and allows measurements of awkward sized
conductors and improved wire access. The illustrations in this manual show the 376.

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Users Manual

How to Contact Fluke

To contact Fluke, call one of the following telephone numbers:

• Technical Support USA: 1-800-44-FLUKE (1-800-443-5853)

• Calibration/Repair USA: 1-888-99-FLUKE (1-888-993-5853)

• Canada: 1-800-36-FLUKE (1-800-363-5853)

• Europe: [phone]

• Japan: [phone]

• Singapore: [phone]

• Anywhere in the world: [phone]

Or, visit Fluke's website at www.fluke.com

To register your product, visit http://register.fluke.com

To see, print, or download the latest manual supplement, visit

http://us.fluke.com/usen/support/manuals

2

.

.

.

Clamp Meters

Safety Information

Safety Information

A Warning identifies conditions and actions that pose hazard(s) to the user. A Caution identifies
conditions and procedures that could cause Meter damage, equipment under test damage, or
permanent loss of data.

Symbols used on the Meter and in this manual are explained in Table 1.

XWWarning

To prevent possible electrical shock or personal injury, follow these guidelines:

• Use the Meter only as specified in this manual or the protection provided by the

Meter can be compromised.

• Examine the case before you use the Meter. Look for cracks or missing plastic.

Carefully look at the insulation around the connectors.

• Never measure current while the test leads are inserted into the input jacks.

• Make sure the battery door is closed and latched before operating the Meter.

• Remove the test leads from the Meter before the battery door is opened.

• Examine the test leads for damaged insulation or exposed metal. Check test lead

continuity. Replace damaged test leads before using the Meter.

• Do not use the Meter if it operates incorrectly. Protection can be compromised.

When in doubt, have the Meter serviced.

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Users Manual

• Do not use the Meter around explosive gas, vapor or in damp or wet

environments.

• Use only type AA batteries, properly installed in the Meter case, to power the

Meter.

• When measuring current with the Jaw, keep fingers behind the Tactile Barrier.

See "The Meter" .

• To avoid false readings that can lead to electrical shock and injury, replace the

batteries as soon as the low battery indicator () appears.

• When servicing the Meter, use only specified replacement parts.

• Have the Meter serviced only by qualified service personnel.

• Be careful around voltages > 30 V ac rms, 42 V ac peak, or 60 V dc. Such

voltages pose a shock hazard.

• Do not apply more than the rated voltage, as marked on the Meter, between the

terminals or between any terminal and earth ground.

• When using the probes, keep fingers behind the finger guards on the probes.

• Connect the common test lead before connecting the live test lead. When

disconnecting test leads, disconnect the live test lead first.

• Do not work alone so assistance can be rendered in an emergency.

• Use extreme caution when working around bare conductors or bus bars. Contact

with the conductor could result in electric shock.

4

Clamp Meters

Safety Information

• Adhere to local and national safety codes. Individual protective equipment must

be used to prevent shock and arc blast injury where hazardous live conductors
are exposed.

• Disconnect circuit power and discharge all high-voltage capacitors before you

measure resistance, continuity, or capacitance.

• For the 374 and 375, do not measure ac/dc current in circuits carrying more than

1000 V or 600 A with the Meter Jaw.

• For the 376, do not measure ac/dc current in circuits carrying more than 1000 V

or 1000 A with the Meter Jaw.

• Never operate the Meter with the back cover removed or the case open.

• Do not measure ac current in circuits carrying more than 1000 V or 2500 A with

the Flexible Current Probe.

• Do not apply the Flexible Current Probe around or remove from HAZARDOUS

LIVE conductors.

• Do not use the flexible current sensor if the inner contrasting insulation color is

showing.

• Take special care during fitting and removal of the Flexible Current Probe. De-

energize the installation under test or wear suitable protective clothing.

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Users Manual

WCaution

To avoid possible damage to the Meter or to equipment under test:

• Use the proper jacks, function, and range for the measurement application.

• Clean the case and accessories with a damp cloth and mild detergent only.

Do not use abrasives or solvents.

Table 1. Symbols

Symbol Meaning Symbol Meaning

B AC (Alternating Current)

F DC (Direct Current) ~

X Hazardous voltage P

6

J

Earth ground

Do not dispose of this product as
unsorted municipal waste. Go to
Fluke’s website for recycling
information.

Conforms to European Union
directives.

Clamp Meters

Safety Information

Symbol Meaning Symbol Meaning

W



®

-

Risk of Danger. Important
information. See Manual.

Battery. Low battery when shown
on display.

Examined and licensed by TÜV
Product Services.

Do not apply to or remove from
HAZARDOUS LIVE conductors.

)

T

;

,

Conforms to relevant North American
Safety Standards.

Double insulated

Conforms to relevant Australian
standards.

Application around and removal from
HAZARDOUS LIVE conductors is
permitted.

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Symbol Meaning Symbol Meaning

IEC Measurement Category III
CAT III equipment has protection

CAT III

8

against transients in equipment in
fixed-equipment installations, such
as distribution panels, feeders and
short branch circuits, and lighting
systems in large buildings.

The Measurement Category (CAT) and voltage rating of any combination of test probe,
test probe accessory, current clamp accessory, and the Meter is the LOWEST rating of
any individual component.

CAT IV

Note

IEC Measurement Category IV
CAT IV equipment has protection

against transients from the primary
supply level, such as an electricity
Meter or an overhead or
underground utility service.

Clamp Meters

The Meter

The Meter

Clamp Meter

fig01.eps

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374, 375, 376

Users Manual

Auto Power Off Backlight

20

ON

10

ON

fig02_3.eps

Clamp Meters

The Meter

Display Hold MIN MAX AVG

=

1x

=

2x

=

3x

2 sec = Exit

fig04_5.eps

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Users Manual

Flexible Current Probe

1

12

2

<0.5 A

>0.5 A

3

fig06.eps

Clamp Meters

The Meter

Jaw

<0.5 A

>0.5 A

Hz

(375 & 376)

1

> 5 A

> 20 A

2

Fig07.eps

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374, 375, 376

Users Manual

1

14

3

<0.5 A

2

Fig08.eps

Clamp Meters

The Meter

dc (375 & 376)

fig09_10.eps

15

374, 375, 376

Users Manual

16

e

e

R

R

ON

<30

Fig15.eps

Clamp Meters

The Meter

Off

On

3

100 ms

1

2

INRUSH

4

fig13_14.eps

17

374, 375, 376

Users Manual

1

3

2

18

fig11_12.eps

Clamp Meters

Specifications

Specifications

Electrical Specifications

AC Current via Jaw

Range

374 and 375 ......................................600.0 A

376.....................................................999.9 A

Resolution ............................................... 0.1 A

Accuracy .................................................2 % ± 5 digits (10-100 Hz)

2.5 % ± 5 digits (100-500 Hz)

Crest Factor (50/60 Hz) ..........................3 @ 500 A (375 and 376 only)

2.5 @ 600 A

1.42 @1000 A (376 only)
Add 2 % for C.F. > 2

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Users Manual

AC Current via Flexible Current Probe

Range ....................................................2500 A

Resolution

374 and 375 ........................................0.1 A (≤ 600 A)

1 A (≤ 2500 A)

376 ......................................................0.1 A (≤ 999.9 A)

1 A (≤ 2500 A)

Accuracy .................................................3 % ±5 digits (5 – 500 Hz)

Crest Factor (50/60Hz) ...........................3.0 at 1100 A (375 and 376 only)

2.5 at 1400 A

1.42 at 2500 A
Add 2 % for C.F. > 2

20

Clamp Meters

Specifications

Position Sensitivity

A

B

C

ghn12.eps

Figure 1. Position Sensitivity

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Users Manual

Distance from

Optimum

A 0.5 in (12.7 mm) 1.4 in (35.6 mm) ± 0.5 %

B 0.8 in (20.3 mm) 2.0 in (50.8 mm) ± 1.0 %

C 1.4 in (35.6 mm) 2.5 in (63.5 mm) ± 2.0 %

Measurement uncertainty assumes centralized primary conductor at optimum position, no
external electrical or magnetic field, and within operating temperature range.

DC Current

Range

374 and 375 ......................................600.0 A

376.....................................................999.9 A

Resolution............................................... 0.1 A

Accuracy .................................................2 % ± 5 digits

AC Voltage

Range

22

i2500-10 Flex i2500-18 Flex Error

Clamp Meters

Specifications

374 and 375 ........................................600.0 V

376 ......................................................1000 V

Resolution

374 and 375 ........................................0.1 V

376 ......................................................0.1 V (≤ 600.0 V)

1 V (≤ 1000 V)

Accuracy .................................................1.5 % ± 5 digits (20 – 500 Hz)

DC Voltage

Range

374 and 375 ........................................600.0 V

376 ......................................................1000 V

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Users Manual

Resolution

374 and 375 ........................................0.1 V

376 ......................................................0.1 V (≤ 600.0 V)

1 V (≤ 1000 V)

Accuracy .................................................1 % ± 5 digits

mV dc

Range

375 and 376.......................................500.0 mV

Resolution............................................... 0.1 mV

Accuracy .................................................1 % ± 5 digits

Frequency via Jaw

Range

375 and 376.......................................5.0 - 500.0 Hz

Resolution............................................... 0.1 Hz

Accuracy .................................................0.5 % ± 5 digits

24

Clamp Meters

Specifications

Trigger Level ........................................... 5 – 10 Hz, ≥10 A

10 – 100 Hz, ≥5 A
100 – 500 Hz, ≥10 A

Frequency via Flexible Current Probe

Range

375 and 376 ........................................5.0 – 500.0 Hz

Resolution ............................................... 0.1 Hz

Accuracy .................................................0.5 % ± 5 digits

Trigger Level ........................................... 5 – 20 Hz, ≥ 25 A

20 – 100 Hz, ≥ 20 A
100 – 500 Hz, ≥ 25 A

Resistance

Range

374.....................................................6000 Ω

375 and 376.......................................60 kΩ

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Users Manual

Resolution

374.....................................................0.1 Ω (≤ 600 Ω)

1 Ω (≤ 6000 Ω)

375 and 376.......................................0.1 Ω (≤ 600 Ω)

1 Ω (≤ 6000 Ω)
10 Ω (≤ 60 kΩ)

Accuracy .................................................1 % ± 5 digits

Capacitance

Range .....................................................1000 μF

Resolution............................................... 0.1 μF (≤ 100 μF)

1 μ F (≤ 1000 μF)

Accuracy .................................................1 % ± 4 digits

Mechanical Specifications

Size (L x W x H) ..................................... 246 mm x 83 m x 43 mm

Weight..................................................... 388 g

Jaw Opening........................................... 34 mm

26

Clamp Meters

Specifications

Flexible Current Probe Diameter ............7.5 mm

Flexible Current Probe Cable Length

(head to electronics connector)...............1.8 m

Environmental Specifications

Operating Temperature........................... -10 °C – +50 °C

Storage Temp .........................................-40 °C – +60 °C

Operating Humidity .................................Non condensing (< 10 – °C)

≤ 90 % RH (at 10 °C – 30 °C)
≤ 75 % RH (at 30 °C – 40 °C)
≤ 45 % RH (at 40 °C – 50 °C)

Operating Altitude ...................................3000 meters

Storage Altitude ......................................12,000 meters

EMC ........................................................ EN 61326-1:2006

Temperature Coefficients........................Add 0.1 x specified accuracy for each degree C above

28 °C or below 18 °C

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Users Manual

Safety Specifications

Safety Compliance.................................. CAN/CSA-C22.2 No. 61010-1-04

ANSI/UL 61010-1:2004
ANSI/ISA-61010-1 (82.02.01):2004
EN/IEC 61010-1:2001 to
1000V Measurement Category (CAT) III
600V Measurement Category (CAT) IV
Pollution Degree 2
EN/IEC 61010-2-032:2002
EN/IEC 61010-031:2002+A1:2008

P

Agency Approvals...................................

Batteries.................................................. 2 AA, NEDA 15A, IEC LR6

28

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