Hioki 3275 Instruction Manual

INSTRUCTION MANUAL

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3274

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CLAMP ON PROBE

Contents

Introduction 1

Inspection 1

Notes on Safety 1

Notes on Use 4

Chapter 1 Overview 9

1.1 Product Overview 9

1.2 Features

9

1.3 Names of Parts

10

1.4 Parts of the Sensor

11

Chapter 2 Specifications 13

2.1 Product Specifications 13

2.2 Standards Applying

14

Chapter 3 Measurement Procedure 17

3.1 Notes on Use 17

3.2 Preparations for Measurement

20

3.3 Demagnetizing and Zero Adjustment

21

3.4 Measurement Procedure

22

1

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WARNING

This device is designed to comply with IEC 61010
Safety Standards, and has been thoroughly tested for
safety prior to shipment. However, mishandling
during use could result in injury or death, as well as
damage to the device. Be certain that you understand
the instructions and precautions in the manual before
use. We disclaim any responsibility for accidents or
injuries not resulting directly from device defects.

Introduction

Inspection

Notes on Safety

Thank you for purchasing this HIOKI 3274 CLAMP ON PROBE.

To obtain maximum performance from the device, please read this

manual first, and keep it handy for future reference.

When you receive the device, inspect it carefully to ensure that no

damage occurred during shipping. If damage is evident, or if it

fails to operate according to the specifications, contact your dealer

or Hioki representative.

Supplied accessories

Instruction manual 1

Carrying case 1

2

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The symbol printed on the device indicates that the user
should refer to a corresponding topic in the manual
(marked with the

symbol) before using the relevant
function.
In the manual, the symbol indicates particularly
important information that the user should read before
using the device.

Wear appropriate protective insulation (insulating rubber
gloves and boots, helmet and etc.) when connecting and
disconnecting from live electric circuits.

DANGER

Indicates that incorrect operation presents an extreme
hazard that could result in serious injury or death to the
user.

WARNING

Indicates that incorrect operation presents a significant
hazard that could result in serious injury or death to the
user.

CAUTION

Indicates that incorrect operation presents a possibility of
injury to the user or damage to the device.

NOTE

Indicates advisory items related to performance or correct
operation of the device.

Safety Symbols

This manual contains information and warnings essential for safe

operation of the device and for maintaining it in safe operating

condition. Before using the device, be sure to carefully read the

following safety notes.

The following symbols in this manual indicate the relative

importance of cautions and warnings.

3

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Measurement categories (Overvoltage categories)

This device conforms to the safety requirements for CAT II

(600V), CAT III (300V) measurement instruments.

To ensure safe operation of measurement devices, IEC 61010

establishes safety standards for various electrical environments,

categorized as CAT I to CAT IV, and called measurement

categories. These are defined as follows.

CAT I : Secondary electrical circuits that are connected to a wall

outlet through a transformer or similar instrument.

CAT II : Primary electrical circuits in equipment connected to a

wall outlet via a power cord (portable tools, household

appliances, etc.)

CAT III : Primary electrical circuits of heavy equip ment (fixed

installations) connected directly to the distribution

panel, and feeders between the distribution panel and

outlets.

CAT IV : The circuit from the service drop to the service entrance,

then to the power meter and to the primary overcurrent

protection instrument.

Higher-numbered categories correspond to electrical environments

with greater momentary energy. So a measurement device

designed for CAT III environments can endure greater momentary

energythanadevicedesignedforCATII.

Using a measurement device in an environment designated with a

higher-numbered category than that for which the device is rated

could result in a severe accident, and must be carefully avoided.

Never use a CAT I measuring device in CAT II, III, or IV

environments.

The measurement categories comply with the Overvoltage

Categories of the IEC60664 Standards.

4

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DANGER

To avoid short circuits and potentially life-threatening
hazards, follow these precautions.
z Never attach the clamp to a circuit that operates at

more than the maximum rated voltage to earth.

z For safety's sake, avoid clamping around bare

conductors, while clamping or measuring.

z While clamping and measuring, do not touch the

clamp in front of the barrier or the conductor being
measured.

z Be careful to avoid damaging the insulation surface

while taking measurements.

z This device is made for use with the 3269 or 3272

POWER SUPPLY. It is possible to use a power
supply other than the 3269 or 3272, provided that
the connector and pin assignments match, and that
voltage and other electrical specifications are
satisfied. In the interest of safety, make sure that
the power supply has a protective earthing with
double-insulation construction.

z Make sure that the waveform measuring equipment

connected to this device's output terminal (BNC) is
equipped with a protective earthing with double­insulation construction.

Notes on Use

Follow these precautions to ensure safe operation and to obtain

the full benefits of the various functions.

5

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DANGER

z If the waveform measuring instrument being

connected to the output terminal (BNC) on this
device is equipped with any other measurement
terminals, take the following precautions to ensure
that the other instrument does not form a bridge
between the probe and any hazardous live of a
part.

1. Isolate the terminal to which the probe is
connected from other terminals on the measuring
instrument using basic insulation

conforming to

the measurement category

, working voltage, and

pollution degree

requirements of the circuit being

tested.

2. If basic insulation

requirements cannot be met
between the terminal to which this device is
connected and other terminals of the measuring
instrument, make sure that the voltage input to
the measurement terminal does not exceed the
Separated Extra-Low Voltage Earthed (SELV-E)

.

3. Read and observe all warnings and precautions
relating to electrical safety for the measuring
instrument being connected to the probe.

Refer to the following standards regarding the
meanings of underlined terms.

IEC 61010-1
IEC 61010-031
IEC 61010-2-032

6

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DANGER

z Be sure to observe all operating precautions for the

waveform monitoring instrument (oscilloscope or
recorder) and other measurement instruments to
which this device is connected

z When using a measurement instrument that does

not provide isolation between its input terminals
and chassis or other input terminals, please pay
attention to the following points.
If a signal is applied to an input terminal other than
that to which this device is connected, do not
connect the ground-side terminal to any non­ground potential. Otherwise, short-circuit current
will flow through the 3269 or 3272, or this device
from the ground terminal, which could cause an
electrical accident or damage.

WARNING

z Do not allow the device to get wet, and do not take

measurements with wet hands. This may cause an
electric shock.

7

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CAUTION

z To avoid damage to the device, protect it from vibration

or shock during transport and handling, and be
especially careful to avoid dropping.

z Do not store or use the device where it could be

exposed to direct sunlight, high temperature, humidity,
or condensation. Under such conditions, the device
may be damaged and insulation may deteriorate so
that it no longer meets specifications.

z Before using the device the first time, verify that it

operates normally to ensure that the no damage
occurred during storage or shipping. If you find any
damage, contact your dealer or Hioki representative.

z This device is not designed to be entirely water- or

dust- proof. To avoid damage, do not use it in a wet or
dusty environment.

z The sensor head is a precision assembly including a

molded component, a ferrite core, and a Hall effect
element. It may be damaged if subjected to sudden
changes in ambient temperature, or mechanical strain
or shock, and therefore great care should be exercised
in handling it.

z The matching surfaces of the sensor head are

precision ground, and should be treated with care. If
these surfaces are scratched, performance may be
impaired.

z Foreign substances such as dust on the contact

surfaces of the sensor head can cause acoustic
resonance and degrade measurement, so it should be
cleaned by gently wiping with a soft cloth.

z To avoid damaging the sensor cable and power supply

cable, do not bend or pull the cables.

8

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CAUTION

z When the power is on, keep closed, except when

clamping them onto the conductor to be measured.
The facing surface of the core section can be
scratched while it is open.

NOTE

z Correct measurement may be impossible in the presence of strong

magnetic fields, such as near transformers and high-current

conductors, or in the presence of strong electromagnetic fields

such as near radio transmitters.

Service / Maintenance

z To clean the device, wipe it gently with a soft cloth moistened

with water or mild detergent. Never use solvents such as

benzene, alcohol, acetone, ether, ketones, thinners or gasoline, as

they can deform and discolor the case.

z If the device seems to be malfunctioning, contact your dealer or

Hioki representative.

z When sending the device for repair, pack carefully to prevent

damage in transit. Include cushioning material so the device

cannot move within the package. Be sure to include details of

the problem.

z Hioki cannot be responsible for damage that occurs during

shipment.

9

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Chapter 1 Overview

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Chapter 1

Overview

1.1 Product Overview

1.2 Features

This device can be directly connected to a BNC input connector

of a waveform measuring instrument such as an oscilloscope or

recorder, and by clamping on a conductor to be measured, allows

the current waveform to be easily captured.

z Highly accurate current detection.
z Easy current measurement.
z Broadband frequency characteristics DC to 10 MHz.
z Large diameter allows high-current measurements.
z Easy protection function to avoid self-heating during excessive

input.

z Unique HIOKI development of thin film Hall effect element

10

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Chapter 1 Overview

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Current direction indication

Terminator

Sensor cable

Power supply cable

"UNLOCK" indication

(inside)

Sensor

"LOCK" indication

3

4

1

5

2

2

7

8

6

9

1.3 Names of Parts

External view

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Chapter 1 Overview

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1.4 Parts of the Sensor

1. Clamp

This clamps around the conductor to be measured.

2. Slider

This slider opens the clamp. Always use it to open and close the

clamp.

3. Lever

This lock mechanism keeps the clamp closed.

4. Sensor head

This clamps the conductor being measured, and carries out the

actual current measurement. It is a precision assembly including a

molded component, a ferrite core, and a Hall effect element. It

may be damaged if subjected to sudden changes in ambient

temperature, or mechanical strain or shock, and therefore great

care should be exercised in handling it.

5. Barrier

This structure reduces the likelihood of touching the conductor

while testing, and indicates the limit of safe physical contact.

Avoid touching the clamp in front of the barrier when clamping

or measuring.

6. Demagnetizing switch (DEMAG)

This demagnetizes the core if it has been magnetized by switching

the power on and off, or by an excessive input. Always carry out

demagnetizing before measurement.

The demagnetizing process takes about 3 second. During

demagnetizing, a demagnetizing waveform is output.

7. Zero adjustment dial (ZERO ADJ)

Use the zero adjustment dial to correct for the effect of a voltage

offset or temperature drift on the device.

When beginning measurement, after demagnetizing always carry

out zero adjustment.

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Chapter 1 Overview

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NOTE

8. Output connector

The current waveform of the measured conductor is output at a

constant rate (0.01 V/A).

Connect to the BNC input connector of the waveform measuring

instrument.

z The output of this device is terminated internally. Use a high-

impedance input to the measuring instrument. With an input

impedance of 50 Ω, accurate measurement is not possible.

z If using BNC-banana plug adapters or similar to connect to input

terminals other than BNC connectors, make sure the polarity is

correct.

z Turn the collar until it clicks, and check that it is locked

securely.

9. Power plug

Connect this to the 3269 or 3272 POWER SUPPLY receptacle to

supply power to the sensor terminator.

13

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Chapter 2 Specifications

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Bandwidth DC to 10 MHz (-3 dB)

(Typical characteristics shown in Fig.1)

Rise time 35 ns or less

Maximum
continuous input
range

150 A
Derating according to frequency shown in Fig.2

Maximum peak
current value

Non-continuous 300 A peak;
at pulse width

30 μs, 500 A peak

Output voltage rate 0.01 V/A

Amplitude
accuracy

To 150 A: 1.0% rdg. 1mV
150 A to 300 Apeak:

2.0% rdg.

(DC,and45to66Hz)

Noise Equivalent to 25 mA rms or less (for 20 MHz band

measuring instrument)

Input impedance (Typical characteristics shown in Fig.3)

Temperature
coefficient for
sensitivity

2% or less (Input: 55 Hz 150 A, within a range of 0

to 40

, within a range of 32 to 104 )

Maximum rated
power

5.5 VA max. (within maximum continuous input range)

Rated supply
voltage

12 V 1V

Chapter 2

Specifications

2.1 Product Specifications

Guaranteed at 23

±

5

(73

±

9

) after the power has been

on for 30 minutes.

14

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Chapter 2 Specifications

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Operating
temperature and
humidity range

0to40 (32 to 104 ), 80 %RH or less (no
condensation)

Storage
temperature and
humidity range

-

10 to 50 (14 to 122 ), 80 %RH or less (no

condensation)

Location for use Indoor, altitude up to 2000 m (6562 feet)

Period of
guaranteed
accuracy

1 year (Opening/Closing up to 10,000 times)

Effect of external
magnetic fields

Equivalent to a maximum of 150 mA (in a DC or 60
Hz, 400 A/m magnetic field)

Maximum rated
voltage to earth

600 V CAT II, 300 V CAT III (insulated conductor)

Diameter of
measurable
conductors

20 mm dia.

0.79" dia.

Cable lengths Sensor cable Approx. 2 m (78.7")

Power supply cable Approx. 1 m (39.4")

External
dimensions

Sensor Approx. 176W X 69H X 27D mm
Approx. 6.93"W X 2.72"H X 1.06"D
Terminator Approx. 27H X 55W X 18D mm
Approx.1.06"W X 2.17"H X 0.71"D

Mass Approx. 500 g

Approx. 17.6 oz.

Accessories Instruction manual, Carrying case

Safety EN61010-2-032:2002

Measurement category II, III (anticipated transient
overvoltage 4000 V), Pollution Degree 2

EMC EN61326:1997+A1:1998+A2:2001+A3:2003

2.2 Standards Applying

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Chapter 2 Specifications

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Fig.1 Frequency characteristics (Typical characteristics)

Frequency [Hz]

A

m

p

l

i

t

u

d

e

[

d

b

,

0

d

B

=

1

V

]

Frequency [Hz]

M

a

x

i

m

u

m

i

n

p

u

t

c

u

r

r

e

n

t

[

A

r

m

s

]

Fig.2 Derating according to frequency

I

n

p

u

t

i

m

p

e

d

a

n

c

e

[

o

h

m

]

Fig.3 Input impedance (Typical characteristics)

Frequency [Hz]

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Chapter 2 Specifications

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17

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Chapter 3 Measurement Procedure

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DANGER

To avoid short circuits and potentially life-threatening
hazards, follow these precautions.
z Never attach the clamp to a circuit that operates at

more than the maximum rated voltage to earth.

z For safety's sake, avoid clamping around bare

conductors, while clamping or measuring.

z While clamping and measuring, do not touch the

clamp in front of the barrier or the conductor being
measured.

z Be careful to avoid damaging the insulation surface

while taking measurements.

z This device is made for use with the 3269 or 3272

POWER SUPPLY. It is possible to use a power
supply other than the 3269 or 3272, provided that
the connector and pin assignments match, and that
voltage and other electrical specifications are
satisfied. In the interest of safety, make sure that
the power supply has a protective earthing with
double-insulation construction.

z Make sure that the waveform measuring equipment

connected to this device's output terminal (BNC) is
equipped with a protective earthing with double­insulation construction.

Chapter 3

Measurement Procedure

3.1 Notes on Use

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Chapter 3 Measurement Procedure

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DANGER

z Make sure that the waveform measuring equipment

connected to this device's output terminal (BNC) is
equipped with a protective earthing with double­insulation construction.

z If the waveform measuring instrument being

connected to the output terminal (BNC) on this
device is equipped with any other measurement
terminals, take the following precautions to ensure
that the other instrument does not form a bridge
between the probe and any hazardous live of a
part.

1. Isolate the terminal to which the probe is
connected from other terminals on the measuring
instrument using basic insulation

conforming to

the measurement category

, working voltage, and

pollution degree

requirements of the circuit being

tested.

2. If basic insulation

requirements cannot be met
between the terminal to which this device is
connected and other terminals of the measuring
instrument, make sure that the voltage input to
the measurement terminal does not exceed the
Separated Extra-Low Voltage Earthed (SELV-E)

.

3. Read and observe all warnings and precautions
relating to electrical safety for the measuring
instrument being connected to the probe.

Refer to the following standards regarding the
meanings of underlined terms.

IEC 61010-1
IEC 61010-031
IEC 61010-2-032

19

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Chapter 3 Measurement Procedure

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DANGER

z Be sure to observe all operating precautions for the

waveform monitoring instrument (oscilloscope or
recorder) and other measurement instruments to
which this device is connected

z When using a measurement instrument that does

not provide isolation between its input terminals
and chassis or other input terminals, please pay
attention to the following points.
If a signal is applied to an input terminal other than
that to which this device is connected, do not
connect the ground-side terminal to any non­ground potential. Otherwise, short-circuit current
will flow through the 3269 or 3272, or this device
from the ground terminal, which could cause an
electrical accident or damage.

20

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Chapter 3 Measurement Procedure

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CAUTION

Before turning on the power, make sure that the voltage
of the power supply being used matches the supply
voltage indicated on the rear panel of the 3269 or 3272.

NOTE

3.2 Preparations for Measurement

(1) Have the 3269 or 3272 POWER SUPPLY, and oscilloscope or

recorder for waveform measurement ready.

z The output of this device is terminated internally. Use a high-

impedance input to the measuring instrument. With an input

impedance of 50 Ω, accurate measurement is not possible.

z Depending on the current value being measured, there are cases

in which two CLAMP ON PROBEs cannot be used

simultaneously on the 3272. Power consumption on the CLAMP

ON PROBE depends on the current value being measured.

(2) Turn the power switch off and connect the power cord.

(3) Connect the power plug of the 3274 to the power receptacle of the

3269 or 3272.

(4) Turn the 3269 or 3272 power switch on, and check that the front

panel power indicator lights.

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Chapter 3 Measurement Procedure

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CAUTION

z When disconnecting the output connector, be sure to

release the lock before pulling off the connector. Forcibly
pulling the connector without releasing the lock, or pulling
on the cable, can damage the terminator.

z If using BNC-banana plug adapters or similar to connect

to input terminals other than BNC connectors, make sure
the polarity is correct.

z Do not demagnetize while the 3274 is clamping a

conductor to be measured. Demagnetizing causes current
to flow into the conductor, which may damage parts in the
circuit to be measured.

Demagnetizing

Conductor

z Check that the conductor being measured is not clamped

when supplying power to the 3274 for the same reason.
Demagnetized waveforms are generated when supplying
electric power.

3.3 Demagnetizing and Zero Adjustment

(1) With the waveform measurement instrument input at ground,

adjust the trace to the zero position.

(2) Set the input coupling of the waveform measurement instrument

to DC.

(3) Connect the output connector of the 3274 to the input connector

of the waveform measurement instrument. Turn the collar until it

clicks, and check that it is locked securely.

22

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Chapter 3 Measurement Procedure

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I

3.4 Measurement Procedure

(4) Before clamping a conductor, confirm that the clamp can be

securely closed: press the slider until UNLOCK is no longer

displayed, and hold it until LOCK appears.

(5) Press the demagnetizing switch (DEMAG) on the terminator.

(6) Turn the zero adjustment dial on the terminator, to adjust the trace

to the zero position.

(1) Check that the system is safe, and that the preparations described

in the preceding section have been carried out.

(2) Pull the sensor slider, so that the clamp opens.

(3) Align the sensor so that the current direction indication

corresponds to the direction of current flow through the conductor

to be measured, and clamp so that the conductor is in the center

of the sensor aperture.

(4) Press the slider on the sensor head until the "UNLOCK"

indication disappears, and hold it until LOCK appears, and check

that the opening lever is firmly locked and the clamp securely

closed.

(5) It is now possible to monitor the current waveform. The output

rate of the 3274 is 0.01 V/A. The current sensitivity can be

derived from the voltage sensitivity of the waveform measurement

instrument. For example, if the voltage sensitivity is 10

mV/division, the current sensitivity is 1 A/division.

23

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Chapter 3 Measurement Procedure

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NOTE

0

100

200

300

400

500

600

0 100 200 300

AC(f=50Hz)
DC

C

o

n

s

u

m

p

t

i

o

n

c

u

r

r

e

n

t

(

m

A

)

Current (A)

CAUTION

z The maximum continuous input range is based on

heat that is internally generated during
measurement. Never input current in excess of this
level. Exceeding the rated level may result in
damage to the probe.

z The maximum continuous input range varies

according to the frequency of the current being
measured. See the figures in Chapter 2,
"Specifications"

z If excess current is input, generated heat activates

a built-in safety function that blocks normal output.
If this happens, remove the input immediately
(remove the sensor from the conductor being
measured, or reduce the input current to zero).
Wait until the sensor has had sufficient time to cool
before resuming operation.

･

When using the 3274, note that two clamp-on probes may not be
used simultaneously with the 3272 POWER SUPPLY, depending
on the current to be measured.

･

The current consumption of clamp-on probes depends on the
current to be measured. Confirm that the total current
consumption of the clamp-on probes does not exceed the rated
output current of the 3272. See Figure 1.

Fig.1

Current consumption* vs. current to be measured (typical)

*The sum total of a positive and negative current consumption

24

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Chapter 3 Measurement Procedure

――――――――――――――――――――――――――――――――――

CAUTION

z Even if the input current does not exceed the rated

continuous maximum, continuous input for an
extended period of time may result in activation of
the safety circuit to prevent damage resulting from
heating of the sensor.

z At high ambient temperatures, the built-in safety

circuit may activate at current input levels below
the rated continuous maximum.

z Continuous input of current exceeding the rated

maximum or repeated activation of the safety
function may result in damage to the device.

z The probe is rated for maximum input under two

conditions in addition to the input maximums
shown in the Product Specifications. These are (1)
300 Apeak, for non-continuous input, and (2) 500
Apeak for pulse widths

30 μs. (1) indicates an
upper waveform response limit of 300 Apeak. Use
the sensor at RMS current input levels that are
within the rated continuous maximums. (2)
indicates the upper response limit for a single input
pulse. Do not allow current level to exceed the
specified limit of the operating range.

z To avoid damage to the device, when opening the

clamp of the probe, be sure to operate with the
slider.

25

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Chapter 3 Measurement Procedure

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NOTE

z The output of this device is terminated internally. Use a

waveform measurement instrument with an input impedance of at

least 1 MΩ.

z Immediately after powering on, this device may be subject to an

appreciable offset drift due to the effect of self-heating. To

counteract this, allow the device to warm up for about 30

minutes before carrying out measurement.

z When performing continuous measurements, it is necessary to be

aware that the offset voltage drifts, depending on factors such as

the ambient temperature.

z Under certain circumstances, oscillation may occur if the probe is

connected to the 3269 or 3272 POWER SUPPLY while the

power supply is on. This does not indicate a malfunction.

Oscillation can be stopped and operation restored to normal by

opening and closing the clamp.

z Acoustic resonance may occur depending on the level and

frequency of the measured current. This does not normally affect

measurements unless a foreign substance such as dust is present

on the contact surfaces of the sensor head.

z The reading may be affected by the position within the clamp

aperture of the conductor being measured. The conductor should

be in the center of the clamp aperture.

z When carrying out measurement, press the slider on the sensor

head until the "UNLOCK" indication disappears, and hold it until

LOCK appears, and check that the opening lever is firmly locked

and the clamp securely closed. Correct measurements cannot be

performed unless the clamp is securely closed and the slider is

pressed until LOCK is displayed.

26

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Chapter 3 Measurement Procedure

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Power source Load

High

Low

z At high frequencies, common mode noise may affect

measurements taken on the high voltage side of circuits. If this

occurs, reduce the frequency range of the waveform measuring

instrument, or clamp onto the low-voltage side of the circuit, as

appropriate.

z When power is turned on, a demagnetizing waveform is initially

applied to the output: this is intentional in the design, and not a

fault.

z Accurate measurement may be impossible in locations subject to

strong external magnetic fields, such as transformers and high-

current conductors, or in locations subject to strong external

electric fields, such as radio transmission equipment.

HIOKI 3274 CLAMP ON PROBE

Instruction Manual

Publication date: September 2006 Revised edition 4

Edited and published by HIOKI E.E. CORPORATION

Technical Support Section

All inquiries to International Sales and Marketing Department

81 Koizumi, Ueda, Nagano, 386-1192, Japan

TEL: [phone] / FAX: [phone]

E-mail: [e-mail]

URL http://www.hioki.co.jp/

Printed in Japan 3274A981-04

All reasonable care has been taken in the production of this manual,
but if you find any points which are unclear or in error, please
contact your supplier or the International Sales and Marketing
Department at HIOKI headquarters.
In the interests of product development, the contents of this manual
are subject to revision without prior notice.
Unauthorized reproduction or copying of this manual is prohibited.

HEAD OFFICE

81 Koizumi, Ueda, Nagano 386-1192, Japan
TEL [phone] / FAX [phone]
E-mail: [e-mail] / URL http://www.hioki.co.jp/

HIOKI USA CORPORATION

6 Corporate Drive, Cranbury, NJ 08512, USA
TEL [phone] / FAX [phone]

3274A981-04 06-09H

Printed on recycled paper

2003-01

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