MULTI MEASURING INSTRUMENTS HWT-301 Instruction Manual

DIGITAL HARMONICS TESTER

MODEL HWT-301

INSTRUCTION MANUAL

Thank you very much for selecting our digital AC digital

harmonics tester.

This model is complex instrument and employ a very reliable

mechanical/electronic design.

Before you use your new instrument, read this Instruction

Manual completely and familiarize yourself thoroughly with

all functions. With proper use and care, your tester will give

you years of satisfactory service.

MULTI MEASURING INSTRUMENTS CO.,LTD.
Akihabara Murai Bldg. 7F, 1-26 Kanda Sakuma-cho,

Chiyoda-ku, Tokyo, Japan, 101-0025

TEL : [phone] FAX : [phone]

Home Page : http://www.mutimic.com/

E-mail : [e-mail]

C O N T E N T S

1. INTRODUCTION ......................................................................... P1.

2. SAFETY SUMMARY ...................................................................... P1.

3. SPECIFICATIONS

3-1 General Specification .................................................................. P2.

3-2 Measuring Range ........................................................................ P2.

3-2-1 All Pass Mode ........................................................................... P2.

3-2-2 Harmonics Mode ...................................................................... P3.

4. DIMENSIONS AND PANEL FUNCTION .................................... P4.

5. METHOD OF MEASUREMENT

5-1 Preparation and Caution before Measurement ........................ P5.

5-2 Line Current Measurement ....................................................... P6.

5-3 Leakage Current Measurement ................................................ P6.

5-3-1 Leakage Current Measurement for Grounding Line ............ P6.

5-3-2 Leakage Current Measurement for Single Phase or

Three Phase Circuit ................................................................ P7.

5-4 Harmonics Current Measurement ............................................ P7.

5-5 Compensation for Influence by the Harmonic Component

of Neighboring Frequency ........................................................ P7.

5-6 Calculation Method of Harmonic Distortion ............................ P8.

5-7 Voltage Measurement ................................................................ P8.

5-7-1 Voltage Measurement for AC 400V Range ............................ P8.

5-7-2 Voltage Measurement for AC 400mV Range ......................... P9.

5-8 Harmonics Voltage Measurement ............................................. P9.

5-9 Resistance Measurement ........................................................... P9.

6. REPLACEMENT OF BATTERIES ............................................... P10.

7.REPAIR SERVICE/WARRANTY .................................................... P10.

1. INTRODUCTION

Model HWT-301 harmonics tester is portable and handheld clamp-on type tester

which is least affected by external magnetic fields.

It measures not only true rms value for line current and leakage current of the low

voltage circuit over a range from 0.1mA to 300A but also the harmonics current and
voltage in the line up to the 25th harmonics.

In addition to above basic measurement functions, model HWT-301 provides voltage

and resistance measurement with a full scale display of 4000 counts as well as
conformity of IEC safety standards.

2. SAFETY SUMMARY

The WARNINGs which appear on the following pages must be followed to ensure

operator safety and to retain the operating condition of the tester.

Safety Symbols:

indicates the operator must refer to an explanation in this manual.

indicates terminals at which dangerous voltages may exist.

△

!

WARNING

● Do not make voltage measurements of power lines carrying more than 250V.
IN SOME CASES, POWER LINES MAY CARRY VOLTAGE SPIKES OF SEVERAL
TIMES OF THE NORMAL SUPPLY VOLTAGE. THIS TESTER SHOULD NOT BE
USED TO MEASURE POWER LINES.
*The term of “POWER LINE” means the electrical circuit providing the power to

factories, buildings, and etc.

● To avoid damage to the tester, disconnect test leads before changing functions.

● Always check to make sure that the function switch is set to the proper position.

● When making measurements, use CAUTION as dangerous voltages may be present

in normally safe areas.

● To avoid electrical shock, use CAUTION when working above 60V DC or 25V AC
rms. Such voltages pose a shock hazard.

● Never make measurements with the case opened.

● Never fail to keep the maximum tolerable input.

● Never operate this tester if it becomes wet, damp or has any liquid condensation

build-up on any part of the instrument.

● Do not operate the tester in presence of flammable gasses or fumes.

● Never make measurements for uninsulated conductors or bus bars.

- P1 -

3. SPECIFICATIONS

3-1 General Specification

Measuring method : Dual integration mode with true rms reading.

Measuring function: Load current, leakage current, harmonics current, AC voltage,

harmonics voltage, resistance.

Safety standard : Meets the requirements for double insulation to IEC61010-1 and

IEC 61010-2-032, Category II 600V or Category III 300V.
E.M.C. standard : Meets EN 61326
Affection of magnetic fields: Less than 3mA (nearby 100A conductor)
Display: 3 3/4 digit LCD, max. reading of 4000 count
Range: Current 0~400mA/4A/40A/300A
Voltage 0~400mV/400V
Resistance 0~4000Ω
Input frequency: 45Hz~65Hz
Sampling : 2 times/s
Over range indication : “OL” mark on LCD
Low battery indication : "B" mark on LCD readout
Data hold indication : "D･H" mark on LCD readout

Jaw opening capability : 40mmφ
Limitation of circuit voltage: Less than AC 600V
Withstanding voltage : AC 3700V, 1 minute (between outer case and core of CT)
Auto power off : The meter is set to power off mode approx. 20 minutes after the

power switch on.
Operating temperature : 0℃ to 40℃, ＜80%RH (non-condensing)
Strange temperature :‐10℃ to 60℃, ＜70%RH (non-condensing)
Power supply : 1.5V (“ AAA” size, R03) x 3
Power consumption and battery life : Approx. 13mA, 50 hours continuous.
Size : 70(W)x223(H)x34(D)mm
Weight : Approx. 440g
Accessories : Carrying case………….. 1

Instruction manual…… 1
Batteries…………………3
Test leads……………… .1 set

3-2 Measuring Range

Note: Electrical characteristic (18℃～28℃, 80%RH max.)

3-2-1 All Pass Mode

AC current (True RMS)

Range

Resolution

Accuracy

400mA

4A

40A

0.1mA
1mA

10mA

±1.0%rdg±8dgt

300A

100mA

±1.0%rdg±1% of full scale

- P2 -