Hioki 3256-50, 3256-51, 3257-50, 3257-51 Instruction Manual

INSTRUCTION MANUAL

3256-50
3256-51

DIGITAL HiTESTER

i

Contents

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

Inspection ............................................................... 1

Safety Notes ...........................................................2

Usage Notes........................................................... 6

Chapter 1 Overview 9

1.1 Product Overv iew ........................... ...... ..9

1.2 Features ..................................................9

1.3 Parts Names and Functions .................10

Chapter 2 Measurement Procedures 15

2.1 Voltage Meas urem en t........................... 16

2.2 Frequency Measurement...................... 18

2.3 Current Measurement........................... 19

2.4 Resistance Measurement..................... 22

2.5 Continuity Chec k............. ...... ...... .......... 23

2.6 Diode Check......................................... 24

Chapter 3 Additional Functions 25

3.1 HOLD AUTO Function ..........................25

3.2 HOLD Function .............. ...... .................26

3.3 Overflow Warning Function ..................27

3.4 Relative Display Function .....................28

3.5 Auto Power Save Function ................... 30

3.6 Voltage Detecti ng Func ti on ...................31

3.7 Dynamic Recording Function ................32

3.8 Memory Function ..................................33

ii

Chapter 4 Specificatio ns 35

4.1 General Specifications ..........................35

4.2 Accuracy ................................................39

Chapter 5 Maintena ce and Service 43

5.1 Replacing the Batteries and Fuses ........43

5.2 Cleaning ................................................45

5.3 Service ..................................................45

1

Introduction

Thank you for purchasing the HIOKI "3256-50/51
DIGITAL HiTESTER". To obtain maximum perfor­mance from the product, please read th is manual
first, and keep it handy for future reference.

Inspection

• When you receive the product, inspect it carefully
to ensure that no damage occurred during ship­ping. In particular, check the accessories, panel
switches, and connectors. If damage is evident, or
if it fails to operate according to the specifications,
contact your dealer or Hioki representative.

• Before using the product 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.

• Before using the product, make sure that the insu­lation on the test leads is undamaged and that no
bare conductors are improperly exposed. Using
the product under such conditions could result in
electrocution. Replace the test leads and probes
with the specified Hioki Model 9207-10.

2

Accessories

3256-50

*1

3256-51

Safety Notes

This manual contains information and warnings
essential for safe operation of the product and for
maintaining it in safe operating condition. Before
using the product, be sure to carefully read the fol­lowing safety notes.

9207-10 TEST LEAD .................. 1

*2

Instruction Manual....................... 1

R03 Manganese battery..............2

(Supplied with this product, for
monitor)

9378 CARRYING CASE
(3256-50 only)

Protective holster

*2

(3256-51only)

*1

This product is designed to conform to 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 product. 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 product defects.

3

Safety Symbols

In the manual, the symbol indicates particu­larly important information that the user should
read before using the product.

The symbol printed on the product indicates
that the user should refer to a corresponding topic
in the manual (marked with the symbol) before
using the relevant function.

Indicates that dangerous voltage may be present
at this terminal.

Indicates a double-insulated device.

Indicates a grounding terminal.

Indicates DC (Direct Current).
Indicates AC (Alternating Current).

Indicates DC (Direct Current) or AC (Alternating
Current).

4

The following symbols in this manual indicate the
relative importance of cautions and warnings.

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

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

Indicates that incorrect operation presents a pos­sibility of injury to t he user or damage to the prod­uct.

Advisory items related to performance or correct
operation of the product.

Other Symbols

❖

Accuracy

f.s.

rdg.

Indicates the quick guide for operations

Indicates the prohibited action

Indicates the reference

We define measurement tolerances in terms of f.s.
(full scale), rdg. (reading) and dgt. (digit) values,
with the following meanings:

(maximum display value or scale length)
The maximum displayable value or the full length
of the scale. This is usually the maximum value of
the currently selected range.

(reading or displayed value)
The value currently being measured and indicated
on the measuring product.

(resolution)

dgt.

The smallest displayable unit on a digital measur­ing product, i.e., the input value that causes the
digital display to show a "1".

5

Measurement categories (Overvoltage categories)

This product complies with CATIII (600 V), CATII (1000 V) safety
requirements.
To ensure safe operation of measurement products, 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 connected to an AC elec­trical outlet through a transformer or similar device.

Primary electrical circuits in equipment connected to

CAT II

an AC electrical outlet by a power cord (portable tools,
household appliances, etc.)

Primary electrical circuits of heavy equipment (fixed

CAT III

installations) connected directly to the distribution
panel, and feeders from the distribution panel to out­lets.

The circuit from the service drop to the service en-

CAT IV

trance, and to the power meter and primary overcur­rent protection device (distribution panel).

Higher-numbered categories correspond to electrical environ­ments with greater momentary energy. So a measurement
device designed for CAT III environments can endure greater
momentary energy than a device designed for CAT II.
Using a measurement product in an environment designated
with a higher-numbered category than that for which the product
is rated could result in a sev ere accident, and mus t be carefully
avoided.
Never use a CAT I measuring product in CAT II, III, or IV envi­ronments.
The measurement categories comply with the Overvoltage Cate­gories of the IEC60664 Standards.

6

Usage Notes

Follow these precautions to ensure safe operation
and to obtain the full benefits of the various func­tions.

• To avoid electric shock, do not allow the
product to get wet, and do not use it when
your hands are wet.

• Do not use the product where it may be
exposed to corrosive or combustible
gases. The product may be damaged or
cause an explosion.

7

Direct

-

st

-

n

n

sunlight

High temper
ature, high
humidity, du

Observe the following to avoid damage to the
product.

• Installation and Operating Environment
Between 0°C and 40°C; 80% RH or less;
indoors only. Howev er, it can be safely operated
at as low as -10°C.

• Do not store or use the product where it could
be exposed to direct sunlight, high tem perature
or humidity, or condensation. Under suc h condi­tions, the product may be damaged and insula­tion may deteriorate so that it no longer meets
specifications.

• This product is not designed to be entirely
water- or dust-proof. To avoid damage, do not
use it in a wet or dusty environment.

• Do not use the product near a device that gener­ates a strong electromagnetic field or electro-

Electromag

etic radiatio

static charge, as these may cause erroneous
measurements.

• To avoid damage to the product, protect it from
vibration or shock during transport and handling,
and be especially careful to avoid dropping.

• Adjustments and repairs should be made only

Impact,

dropping

by technically qualified personnel.

• If the protective functions of the product are
damaged, either remove it from service or mark
it clearly so that others do not use it inadvert­ently.

• To avoid corrosion from battery leakage, remove
the batteries from the product if it is to be st ored
for a long time.

8

• Accurate 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.

• To avoid battery depletion, turn the function
selector OFF after use (the Auto Power Save
feature consumes a small amount of current).

• The indicator appears when battery voltage
becomes low. Replace the batteries as soon as
possible.

9

1.1 Product Ov e r view

Overview Chapter 1

1.1 Product Overview

This measurement product is a multi-functional
digital multimeter capable of measuring DC and
AC voltages, DC and AC currents, and the resis­tance, checking the diode and continuity, and
detecting voltage.

1.2 Features

Compliance with CE marking requirements

The measurement product is designed to comply
with the international safety standard (IEC61010-

1) and EMC standards.

Safety-designed handy digital multimeter

The measurement product is equipped with test­lead misinsertion preventive shutters and fast -act­ing fuses at the current measurement terminals.

Multi-functional and voltage detecting

• Live conductors can be examined safely and easily.

• The Hold Auto function allows measur ed v alue s to
be maintained by simply disconnecting the test
leads.

• The Hold function maintains the displayed value.

• The Memory function saves the held value dis­played.

• The Recording function displays the maximum,
minimum, average, and currently measured values
selectively.

• The Relative function displays any discrepancy
from the reference.

1.3 Parts Names and Functions

10

1.3 Parts Names and Functions

*: for details, see
the following
pages

REC•MEMO

Button

(Press this button
to change to the
function indi ca t­ed in blue.)

For other func­tions, see the fol­lowing pages.

LCD display *

H.AUTO/REL

Button *

RANGE

Button *

V.Ω terminal

Terminal used to
measure volta g­es and resis­tances

(red test lead)

COM terminal

Terminal com mon to
all functions

(black test lead)

The terminal shutter works together with the
function selector to prevent incorrect operation.
Note that if the function selector is toggled with
the test leads connected, the measurement
product may be damaged.

Function
Selector

(Selects functions
and turns the
power on/off)

A terminal

Terminal used to
measure currents
in 10-A mode

μA.mA terminal

Terminal used to 
measure currents in

μA/mA mode

11

1.3 Parts Names and Functions

LCD(Display)

n
n

r

d

s

k

­s

-

)

­)

-

Indicates HOLD AUTO/

HOLD function

Indicates Relative functio n
Indicates Autorang ing

function
Indicates DC

voltage/cur­rent function

Indicates AC
voltage/cur­rent function

Indicates low
battery volt­age

Lights up when the voltage
drops below the battery
accuracy guarantee voltage
(2.2±0.1 V)

REC•MEMO

Decimal point

Indicates Recording function

Indicates Continuity Check functio

Indicates Diode Check functio

Indicates Auto Powe

Save is enabl e

Frequency unit
Resistance and

continuity chec
units

Voltage and di
ode check unit

Current unit s
Indicates the

memory data

number
Bar-graph scale (42 dots)
Bar graph (with polarity indicator)

H.AUTO/REL RANGE

Changes to the func­tion indicated in blue

Toggles between AC
and DC modes(Cur­rent measurement)

(page 19)

Recording function
(Displays MAX/MIN/
AVG)*1

(page 32)

Voltage Detecting

(page 31)

Memory Function

(page 33)

Cancels the Auto
Power Save function
*2

(page 30)

HOLD AUTO function
(Holds the measured
value)

(page 25)

Turns the HOLD
function on/off

Turns the Relative
function (displaying
the relative value) on/
off*1

*1: Press the button for at least 1 second (REC

and REL require the button to be pressed
for a longer time).

*2: Turn on the power while pressing the but-

ton, and hold the button down until a beep
ing sound is generated (power-on option).

*2

(page 26)

(page 28)

Changes the manual
range and selects
range
Changes the auto
range from the manu
al range*1

Changes the input
level
(Frequency fun cti on )

Calls data from mem
ory*2

(page 18

(page 34

1.3 Parts Names and Functions

12

t

Function Selector

n

theses.

t

nt

( )

t

( )

t

( )

nt

10A

( )

nt

nt

(

)

nt

( )

nt

(Diode Check function)

Continuity function

Resistance function

DC voltage function

(Voltage detecting)

(Frequency

function)

AC voltage

function

Power OFF

Quick Reference

Indicates the function selector position

V

Indicates the terminal to which the red
test lead should be connected
Indicates the terminal to which the
black test lead should be conn ecte d

Press

REC•MEMO

when the
function in parentheses is being
used.

μA DC/AC current

40

function

μA DC/AC current

function

mA DC/AC curren

function
10A DC/AC

current function

Example

Switches betwee

REC•MEMO

( )

measurement to
display in paren-

Measurements Operations (page)

AC voltage
DC voltage

DC/AC Current
(40 μA)

DC/AC Current
(400/4000 μA)

DC/AC Current
(40/400 mA)

DC/AC Current
(10A)

Resistance
Continuity

V

V

40μA

μ

A

mA

Ω

REC•MEMO

REC•MEMO

REC•MEMO

REC•MEMO

REC•MEMO

Measuremen

Measureme

Measuremen

Measuremen

Measureme

Measureme

Measureme

Measureme

16
16

20

20

21

21
22
23

Diode

REC•MEMO

Measureme

24

13

1.3 Parts Names and Functions

V

e-

V

Bring test leads
c

r

line.

).

Example

V/ V/Ω/
4
10A

V/ V/Hz/Ω/

A/mA/10A

L

/

A/mA/10A

4
1

D
r

Frequency

Voltage
detecting

REC•MEMO

"Hz"

lights up

REC•MEMO

"1"

lights up

RANGE

( 1 - 4 )

×

2

RANGE

( 1 - 4 )

Measur
ment

lose to the powe

18

31

Quick Reference (application)

REC•MEMO

:Button

<1 second:
Press the button for at least 1 second.

Hold the measured value. (HOLD AUTO function)

This function is used when the displayed value cannot be checked during
measurement (such as when necessary to measure the conductor in a
dark place or using both hands.

REC•MEMO

: Turn on the power while pressing

the button (hold the button down
until a beeping sound is generated

0μA/μA/mA/

H.AUTO/REL

"HOLD"
Blinking

Move th e test lead s away from
the measurement object.

(Intermittent

sound)

25

Hold the measured value. (HOLD function)

//40μA/

H.AUTO/REL

Measure-

ment

H.AUTO/RE

26

μ

"O.F" is displayed to provide a warning

(Overflow Warning function)

V/ V/40μA

μ

When the measured value exceeds the maxi­mum value, "O.F" is displayed.

27

Use this function to check any disc repancy f rom t he r eference,
or to control the resistance for the purpose of zero adjustment

(Relative function)

V/ V/Ω/
0μA/μA/mA/
0A

isplay the

eference.

Cancellation: H.AUTO/REL (press again)

H.AUTO/REL

(<1 second)

("REL"

lights up)

28

1.3 Parts Names and Functions

14

V
4
10A

.

("APS"

Power

4
1

R

(

L

)

4
1

)

4
1

.

E

4
10A

Cancel the Auto-Power Save function.

(Auto-Power Save function)

V/ V/Hz/

D/Ω///

0μA/μA/mA/

REC•MEMO

Enable the Power Save function:

OFF

Function

change

Press this button unt il a
beeping sound is generated

lights up)

10 minutes

After

Save

mode

30

Check the maximum, minimum, and average values during
measurement. (Recording function)

V/ V/Ω/
0μA/μA/mA/
0A

EC•MEMO

<1 second)

MAX:maximum value/ MIN:minimum value/
AVG:average value / MAX MIN AVG: Current
value
Cancellation: REC

("

MAX MIN A VG"

lights up

•MEMO (press aga in)

)

H.AUTO/R E

(

MAX MIN AVG

32

Save the measured value to memory. (Memory function)

V/ V/Ω/
0μA/μA/mA/
0A

Hold the dis­played value

H.AUTO/REL

REC •MEMO

("MEM."
lights up

33

Call the saved data.

V/ V/Ω/

RANGE

0μA/μA/mA/
0A

Delete all data from memory.

V/ V/Ω/

RANGE

0μA/μA/mA/

Memory-data

V

REC•MEMO

V

display

Select MEM#

(<1 second)

RANG

34

RANGE

34

15

1.3 Parts Names and Functions

Measurement
Procedures

Observe the following precautions to avoid
electric shock.

• Always verify the appropriate setting of the
function selector before connecting the
test leads.

• Disconnect the test leads from the mea­surement object before switching the func­tion selector.

• When it is necessary to replace the mea­surement terminal, remove the test lead
from the measurement object and discon­nect the lead from the terminal before tog­gling the function selector.

Chapter 2

Even when the shutter is closed, the termi­nals are not sufficiently separated. To avoid
electrocution, do not touch the terminals.

When the shutter is damaged, discontinue mea­surement and repair it.

2.1 Voltage Measurement

16

n

V

r
r

r

t
,

d

2.1 Voltage Measurement

• The maximum input voltage is 1000 VDC,

7

1000 Vrms, or 10
However, for CATIII circuits, the maximum
voltage is 600 Vrms. Attempting to mea­sure voltage in excess of the maximum
input could destroy the product and result
in personal injury or death.

• To avoid electrical shock, be careful to
avoid shorting live lines with the test leads.

• For safety, test lead connections must
always be made at the secondary side of a

V•Hz.

AC Voltage

Measurement

circuit breaker.

• The maximum rated voltage between input
terminals and ground is 1000 V DC/AC

7

(CATII), 600 V DC/AC(CATIII), or 10

V•Hz.
Attempting to measure voltages exceeding
this limit with respect to ground could dam­age the product and result in personal
injury.

DC Voltage

Measurement

1. Move the functio

selector to the
position for AC mode o

to the V position fo
DC mode (in eithe
case, “V” lights up).

Red

Black

2. Connect the red tes

lead to terminal V.Ω
and the black test lea
to termina l COM.

17

2.1 Voltage Measurement

2.

o
t,
d

AC Voltage Measurement

Black

Red

DC Voltage Measurement

Black

Red

3. Connect the test leads t

the measurement objec
and read the indicate
value.

Selecting the manual
range:
Reselecting the auto
range:

Holding the measured
value:

HOLD AUTO Function,

page 25) or

HOLD Function, page

26)

Appearance of O.F: The measured value exceeds 4200

Press RANGE
("AUTO" is turned off)
Press RANGE
ond) ("AUTO" lights up)

Press H.AUTO/REL
ment
Move the test leads away from the
measurement object.

Press H.AUTO/REL
Measurement

REL

counts (up to the 420-V range) or
1050 counts (1000- V ran ge ).

→ Intermittent sound →

(for at least 1 sec-

→ Measure-

+Power-on →

→ Press H.AUTO/

The indicated value may vary due to the existence
of induced voltage under no-power conditions.
However, this is not a problem.

2.2 Frequency Measurement

18

1.

"

)

-

2.2 Frequency Measurement

• The maximum input voltage is 1000 VDC,

7

1000 Vrms, or 10
However, for CATIII circuits, the maximum
voltage is 600 Vrms. Attempting to mea­sure voltage in excess of the maximum
input could destroy the product and result
in personal injury or death.

• For safety, test lead connections must
always be made at the secondary side of a
circuit breaker.

V•Hz.

Move the function selector to
the V position and press

the REC
lights up).

REC•MEMO

2. Connect the red test lead to

terminal V.Ω, and the black
test lead to terminal COM.

3. Select the input level (1 to 4

using the RANGE button, in
accordance with the input volt
age.

4. Connect the test leads to the

measurement object, and read

RANGE

Input level

Attenuation factor of the input voltage
(1/10n)
(n: Scale num be r)
Indication range: 0.5 Hz to 500 kHz

the indicated value.

•MEMO button ("Hz

Input level Range

1

0.8 to 4 V

2

4 to 40

3

40 to 400 V

4

400 to 1000V

4.200V

42.00V

420.0V
1000V

Canceling the frequency
measurement:

Press REC•MEMO

19

2.3 Current Measurement

2.3 Current Measurement

• Never apply voltage to the test leads when
a current measurement function is
selected. Doing so may damage the prod­uct and result in personal injury.

• To avoid electrical accidents, remove
power from the circuit before connecting
the test leads.

• To avoid electrical shock, do not use the
product to measure current in circuits of
600 V or greater. The current function
overload protection trips at 600 Vrms.

• Maximum input current in each range
40μA/μA/mA range: 420mADC/ 420 mA rms
10A range: 10 ADC/ 10 A rms
Do not input a current in excess of this
value. Otherwise, the measurement prod­uct will be damaged, resulting in an acci­dent that may cause injury or deat h.

Select ing t he man ual ra nge:
Reselecting the auto range:

Holding the measured
value:

HOLD AUTO Function,

page 25) or

Press RANGE
("AUTO" is turned off)
Press RANGE (for at least 1 sec­ond) ("AUTO" lights up)

Press H.AUTO/REL

ment → Intermittent sound →

Move the test leads away from the
measurement object.

→ Measure-

HOLD Function, page 26)

Appearance of O.F: The measured value exceeds

Press H.AUTO/REL
Measurement →
Press H.AUTO/REL

1050 counts(10-A range) or 4200
counts (other range s).

+Power-on →

2.3 Current Measurement

20

1.

e

g

r-

st

e
d

t

e

g

r-

t

e
d

40μA Measurement (42μA range)

Move the function se lector to th

40μA position.

REC•MEMO

2. Select DC ( ) or AC ( ) usin

the REC•MEMO button.

3. Connect the red test lead to te

minal μA.mA, and the black te
lead to terminal COM.

4. Connect the test leads to th

Black

μA

Red

Measurement

1. Move the function selector to th

REC•M EMO

2. Select DC ( ) or AC ( ) usin

3. Connect the red test lead to te

measurement object, and rea
the indicated value.
The Auto Range function is no

provided.

(420 μA/4200 μA

μA position.

the REC•MEMO button.

minal μA.mA, and the black tes
lead to terminal COM.

range

)

Black

Red

4. Connect the test leads to th

measurement object, and rea
the indicated value.

21

2.3 Current Measurement

1.

e

g

­t

e
d

1.

e

g

i­o

-

e

t

mA

Black

Measurement (40 mA/400 mA)

Move the function selector to th

mA position.

REC•MEMO

2. Select DC ( ) or AC ( ) usin

the REC•MEMO but ton.

3. Connect the red test lead to ter

minal μA.mA, and the black tes
lead to terminal COM.

4. Connect the test leads to th

Red

measurement object, and rea
the indicated value.

A

Measureme nt

Note that the product may be damaged if current
exceeding the selected measurement range is
applied for a long time (for the 10 A range, continu­ous current m ust be limited to 7A, or to less than
one minute if over 7A)

REC•MEMO

Black

Red

(10 A range)

Move the function selector to th

10A position.

2. Select DC ( ) or AC ( ) usin

the REC•MEMO button.

3. Connect the red test lead to term

nal A, and the black test lead t
terminal COM.

4. Connect the test leads to the mea

surement object, and read th
indicated value.
The Auto Range function is no
provided.

2.4 Resistance Measurement

22

e

r-

d

e
d

2.4 Resistance Measurement

• Never apply voltage to test leads when
the Resistance function is selected.
Doing so may damage the product and
result in personal injury.

• To avoid electrical accidents, remove
power from t he circuit before measur ing.

1. Move the function selector to th

Ω position.

Red

Black

Black

2. Connect the red test lead to te

minal V.Ω, and the black test lea
to term i n a l COM.

3. Connect the test leads to th

measurement object, and rea
the indicated value.

Red

Selecting the manual range:
Reselecting the auto range:

RANGE (AUTO is turned off)
RANGE

ond) ("AUTO" lights up)

(Pr es s for at l east 1 sec-

Holding the measur ed
value:

HOLD AUTO Function,

page 25) or

HOLD F unction, page 26)

H.AUTO/REL

→Intermittent sound→

Move the test leads away from the
measurement object.

H.AUTO/REL

surement →H.AUTO/REL

→Measurement

+Power-on→ Mea-

23

2.5 Continuity Check

e

e

).

r-

d

e

2.5 Continuity Check

• Never apply voltage to test leads when
the Continuity function is selected. Doing
so may damag e the product and res ult in
personal injury.

• To avoid electrical accidents, remove
power from the circuit before measuring.

1. Mov e the function selector to th

position.

2. Select Diode ( ) using th

REC•MEMO

REC•MEMO

button ( lights up

Red

Black

Black

Red

3. Connect the red test lead to te

minal V.Ω, and the black test lea
to terminal COM.

4. Connect the test leads to th

measurement object.

When the continuity (threshold:
50±30 Ω or less) is established,
the beeping sounds and the
resistance is displayed
(fixed to the 420-Ω range).

2.6 Diode Check

24

e

e

).

r-

d

e

t-

l

2.6 Diode Check

• Never apply voltage to test leads when
the Diode Check function is selected.
Doing so may damage the product and
result in personal injury.

• To avoid electrical accidents, remove
power from t he circuit before measur ing.

1. M ove the function selector to th

position.

REC•MEMO

Red

Black

Cathode Anode

2. Select Diode ( ) using th

REC•MEMO

button ( lights up

3. Connect the red test lead to te

minal V.Ω, and the black test lea
to termina l COM.

4. Connect the test leads to th

measurement object.
The display shows forward vol

age (0.4 V to 0.7 V) for a norm a
diode.

Black

Appearance of O.F: The diode is invertedly connected or

Appearance at approxi­mately 0 V:

Red

broken.
The diode is short-circuited.

25

Additional

)

e

ce

t o

rm

mo

ct.

est

3.1 HOLD AUTO Function

Functions

Chapter 3

3.1 HOLD AUTO Function

Functions
Description

H.AUTO/REL

HOLD

(blinks)

Measure

V/ V/Ω/40μA/μA/mA/10A

Simply moving the test leads away from the mea­surement object holds the measured value. This
function is useful when it is difficult to read the
displayed value in the current location or both
hands are being used to conduct the measure­ment.

1. Select the desired function and connect th

the measurement product.

2.

Press the H.AUTO/REL button.

("HOLD" blinks) (In the measurement of resistan
played.)

HOLD

(lights up)
Beeping

sound

HOLD

(blinks)

The measured
value is held.

Blind zone V/ V:

Ω: O.F

Canceling the hold
mode:

3. Connect the test leads to the measuremen

4. When the intermittent sound is heard,

A/ A: less than 40 counts

HOLD AUTO is disabled in the AC/DC 420-mV
range.

the measured value is stabilized, an inte
is generated.

("HOLD" lights up)

leads away from the measurement obje
sured value immediately before the t
removed is held.

("HOLD" blinks)

420 mV range, less than 400 counts (other range

Press H.AUTO/REL again.
(HOLD is turned off)

Saving the data: Press

REC•MEMO

3.2 HOLD Function

26

g
d
g
e
d

n
e

e

3.2 HOLD Function

Functions
Description

H.AUTO/REL

H.AUTO/REL

The measured

value is held.

V/ V/Hz/Ω///40μA/μA/mA/10A

This function holds the currently measured
value.

1. Turn on the power while pressin

the H.AUTO/REL button, and hol

Measure

Displayed
value

the button down until a beepin
sound is generated (toggle th
function selector to the desire
position).

2. Press the H.AUTO/REL butto

HOLD

lights up

again at the measured value to b
held. The value is held.

("HOLD" lights up)

3. To cancel the hold mode, pres s th

H.AUTO/REL button again.

The Hold function is active until the measurement
product is turned off.

27

3.3 Overflow War ning Function

3.3 Overflow Warning Function

Functions
Description

V/ V/40μA/μA/mA/10A

When the measured value exceeds the maxi­mum indication (4200 counts), O.F is displayed
and an intermittent sound is generated.

When the measured value exceeds 1050 counts in
the ranges specified below, O.F is displayed and
an intermittent sound is generated.

• Maximum range (1000-V range) of DC voltage
measurement ( V) or AC voltage measurement
(V)

• 10-A range of current measurement

Example: When the measured value exceeds
1050 counts in the 1000-V range of AC voltage

measurement ( V)

3.4 Relative Display Function

28

r
d
o

o

L

d
d

n
d

Checking any discrepancy from the reference (when 10 V is

3.4 Relative Display Function

Functions
Description

V/ V/Ω/40μA/μA/mA/10A

Once an arbitrary value is specified as a refer­ence, the relative value ag ainst the reference is
displayed. This function is useful to check any
discrepancy from the reference.

defined as the reference in the voltage measurement)

Measure a voltage of 10 V

1. Move the function selecto

to the desired position an
connect the test leads t
the measurement product.

(example: V)

2. Connect the test leads t

The manual
range is
enabled.

The bar graph
indicates the
measured value.

H.AUTO/REL

for at least
1 second

the measurement object.

3. Press the H.AUTO/RE

button for at least 1 secon
for the value to be define
as the reference.

(Example: Press the button at
10 V. "REL" lights up and
“0000” is displayed.)

4. Measure the voltage agai

and read the displaye
value (discrepancy from
the reference).

(The measured value minus the
reference is displayed.)

Any discrepancy from the reference
(10 V) is displayed. In the case of a
negative value, “-” is also displayed.

The measurement range is fixed to the range that
is active when the
If the reference value deviates from the full scale,
O.F is displayed. While O.F is displayed, the Rela­tive function is disabled.

H.AUTO/REL button is pressed.

29

3.4 Relative Display Function

r

-

e

s.
st

L

c-

to

t,
d

Application: Using the Relative Display function for the purpose
o

f zero adjustment in the measurement of low resistances

Short-circuit the test leads

1. Move the function selecto

to the Ω position and con
nect the test leads to th
equipment.

2. Short-circuit the test lead

The resistance of the te
leads is displayed.

3. Press the H.AUTO/RE

H.AUTO/REL

for at least
1 second

button for at least 1 se
ond.
("REL" lights up, "0000")

4. Connect the test leads

the measurement objec
and read the indicate
value.

Measure the resistance.

Canceling the Relative
function:

Press H.AUTO/REL

3.5 Auto Power Save Function

30

3.5 Auto Power Save Function

Functions
Description

All functions
Approximately 10 minutes after completing final

operation, the measurement product automati­cally enters Power Sa ve mode. When the mea­surement product is turned on, it automatically
enters Auto Power Save mode ("APS" lights up).

• In Power Save mode, the LCD is blank but power
is supplied to the measurement product.

• To avoid battery depletion, turn the function
selector OFF after use (the Auto Power Save
feature consumes a small amount of current).

Recovery from Power Save mode:

Turn off the function selector. In the current mea­surement, disconnect the test leads from the termi­nals and turn off the function selector.

After the measurement product exits Power Save
mode, all conditions are reset . If t he m easur ement
product is to be us ed f or an extended perio d, Aut o
Power Save mode should be canceled in advance.

Canceling the Auto Power Save function:

REC•MEMO

The Auto Power Save function is disabled until the
measurement product is turned off (APS is turned
off).

Turn on the measure­ment product while press­ing the

REC•MEMO button.

(Hold down the button
until the beeping sound is
generated.)

31

3.6 Voltage Detecting Function

o

s

e

t

r

e
e

r

e
n

-

3.6 Voltage Detecting Function

This function should be used for the covered
power line. Depending on the measurement sta­tus, the power may not be detected. Before using
this function, check that the measuring device can
detect the existing live power line.

Functions
Description

REC•MEMO

V

This function allows you to check whether the
power line is live. If the line is live, the measure­ment product indicates that fact both audibly
(intermittent sound) and visually (display).

1. Move the f unction selector t

the V position, and pres
the REC•MEMO button twic

(“1” lights up).

2. Bring the measuremen

product close to the powe
line.

3. If necessary, change th

detection range with th

RANGE button.

Guidelines for detect­ing power line level
1-3: Approx. 100 V
4: Approx. 200 V

RANGE

When the line is live, the ba
graph fluctuates.
When the voltage is outsid
of the detection range, a
intermittent sound is gener
ated and the display blinks.

The voltage detecting sensor is
mounted at the top of the mea­surement product.
Bring the top close to the
power line, as shown at left.

3.7 Dynamic Recording Funct ion

32

1.

n
o

e

t-

e

­f

­:

-

-

3.7 Dynamic Recording Function

Functions
Description

REC•MEMO

Current
value

Maximum value

Minimum value

Average value

V/ V/Ω/40μA/μA/mA/10A

This function allows the maximum (MAX), mini­mum (MIN), average (AVG ), and currently mea­sured values to be displayed selectively. It is
useful for measuring any discrepancy over an
extended period.

Select the desired functio

Press
for at least
1 second.

and connect the test leads t
the measurement product.

2. Connect the test leads to th

measurement object.

3. Press the

REC•MEMO

bu

ton for at least 1 second.

H.AUTO/REL

("MAX MIN AVG" lights up)

4. Select the item using th

H.AUTO/REL

• The maximum, minimum, and aver
age measured after the acti vation o
the Recor ding f unction a re au tom ati
cally recorded (recording interval
approx. 0.4 seconds).

• When the maximum and/or minimum
is updated , a beepin g sound is g en
erated.

• The simple average is displayed
within 30 min from the star t of mea
surement and t he moving ave rage is
displayed after the elapse of 30 min.

• While the Recording function is in
operation, the Auto Power Save
function is disabled (APS is turned
off). The range is fixed.

button.

Appearance of O.F: The measurement range exceeds the

Canceling Press REC

specified level.
Before using the Recording function, use
the manual range to set the range as­sumed as the maximum level.

•MEMO again.

33

3.8 Memory Function

e
d

n

­f

t

e

3.8 Memory Function

Saving data to memory

Functions
Description

REC•MEMO

V/ V/Ω/40μA/μA/mA/10A

This function memorizes the measured value
held using the Hold Auto or Hold function.

1. Hold the measured valu

using the Hold Auto or Hol
function.

2. Press the REC•MEMO butto

in hold mode. The value dis
played is saved in mem ory o
the number specified.

Wait a moment for curren
value display on the LCD.
Up to 20 values can b
saved.

Memory numbers cannot be specified.
The data is saved to the memory in order, start­ing from 01. When the memory number reaches
20, the subsequent data sets are overwritten to
memory starting from number 01.

3.8 Memory Function

34

e

.

o

t-

s

o
r.
d

e

.

Calling data from memory

Call data from memory as specified below.

RANGE

1. Turn on the power whil

pressing the RANGE button
Move the function selector t

the V position (hold the bu

ton down until a beeping sou nd i
generated).

2. Press the RANGE button t

select the memory numbe

RANGE

When there is no data
in memory

Deleting all data from memory

The saved data is displaye
on the LCD.

Delete all data from memory as specified below.

REC•MEMO

Press both buttons
simultaneo usly for at
least 1 second.

RANGE

Data in the memory of the specified number cannot
be deleted.

Returning to the
normal mea­surement mode:

In Memory Call mode, press th

REC•MEMO and RANGE buttons

simultaneously for at least 1 second
All data is deleted from memory.

Toggle the function selector.
(Five minutes after completing final operation,
the measurement product returns to the nor­mal measurem ent mo de. )

35

4.1 General Specifications

Specifications Chapter 4

4.1 General Specifications

Measurement
Method

AC Measurement
System

Function

Additional
Function

Dual integration

Average rectifying measurement 
DC voltage ( V), AC voltage( V),

Resistance (
AC current ( A), Continuity check( ),

Diode check( ), Frequency (Hz ),
Voltage detecting

Auto Range function
Manual Range function
Hold functi o n
Hold Auto function
Relative Display Function
Dynamic Recording function
Memory function (Registration, call, deletion)
Auto Power Save function
Overflow Warning function
Battery-Life Warning function

Ω), DC current ( A),

Display Type TN type LCD, 1/4 duty, dynamic drive
Display Elements 3(1/2) dgt.

Units and Symbols

Bar-graph
Indicator

Max. 4200 counts (19,999 counts for Hz
function)
Number display: "20"
Polarity indicator: "–" sign (automatic)
Overflow indicator: "OF" or "–OF"

AUTO/REL/HOLD/MAX/MIN/AVG/ / /
APS

M/k/m/μ/Hz/Ω/A/V/ / / /MEM
Indication of scale, 42-dot bar graph, and ±

(polarity)

4.1 General Specifications

36

Input Terminals V.Ω ter m i n a l (V, Hz, Ω, continuity, diode)

μA.mA/ A/ COM terminals

Equipped with terminal shutter to prevent

improper operation.
Function Selector Rotary selector
Range Switching Auto/Manual Range
Sampling Rate 2.5 S/s (except Frequency), 5 S/s (Fre-

quency), 25 S/s (Update of bar graph)
Power Supply Two manganese (R03) batteries or

two alkaline (LR03) batteries

Rated supply voltage:1.5VDC × 2
Battery-Life

Warning
Continuous

Operating Time

Maximum Rated
Voltage to Earth

Maximum Input
Voltage

Maximum Input
Current

indicates low battery

(2.2 V±0.1V or less)

Approx. 100 hours

( V, with R03 manganese batteries)

Approx. 200 hours

( V, with LR03 alkaline batteries)

1000VDC/ 1000Vrms(sin), or 107V•Hz(CATII)

7

600VDC/ 600Vrms(sin), or 10

V•Hz(CATIII)

V/ V/Ω/Hz

1000VDC/ 1000Vrms(sin), or 107V•Hz(CATII)

600VDC/ 600Vrms(sin), or 10

7

V•Hz(CATIII)

A/ A

42μA - 420mA range: 420 mA DC/AC

(fuse 0.5A/700V DC/AC)

10A range:10 A DC/AC

(fuse 10A/600V DC/AC)
Dielectric Strength Input terminals to case:

Noise Suppression

Maximum Rated
Power

7.4 kVrms sin (50/60 Hz for one minute)

NMRR: V -60dB or better (50/60 Hz)

CMRR: V -100dB or better (50/60 Hz)

V -60dB or better (50/60 Hz)

20 mVA (supply voltage 3.0 V)

0.1 mVA (Auto Power Saving,

supply voltage 3.0 V)

37

4.1 General Specifications

Operating

Indoors, altitude up to 2000 m (6562-ft.)

Environment
Operating Tem per-

ature & Humidity
Storage Tempera-

ture & Humidity
Tem peratur e

Characteristic

0 to 50°C (32 to 122°F), at 80%RH or less
(non-condensating)

-20 to 60°C (-4 to 140°F), at 70%RH or
less (non-condensating)

(Measurement accuracy) × 0.1/°C
(except 23±5°C)

Size & Weight Approx.76W × 167H × 33D mm

(2.99"W × 6.57"H × 1.30"D)

without protrusions

(

)

Approx. 260 g (9.2 oz)

Accessories 9207-10 TEST LEAD

Instruction Manual
Two R03 manganese batteries
Protective holster(3256-51) or
9378 CARRYING CASE (3256-50)

Applicable
Standards

Safety EN61010-1:2001

EN61010-031:2002
Pollution Degree 2
Measurement Category III(600 V),
Measurement CategoryII(1000 V)
(Anticipated Transient Overvolt­age: 6000 V)

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

+A3:2003

Options 9207-10 TEST LEAD

9014 HIGH VOLT AGE PROBE*(30 kVDC)
(*no CE marking)
3853 CARRY ING CASE (for 3256-51 can
be packag ed together with the holster.)
9378 CARRYING CASE (St andard item for
the 3256-50)

4.1 General Specifications

38

Protective Fuse 10A terminal: TDC600-10A

(made by Cooper Bussmann*)

Rating 10 A/600 VAC Fast-Acting

Breaking capacity: 10 kA/250 VAC,

200 A/600 VAC

μAmA terminal:70125 (made by SIBA Inc.)

Rating 0.5 A/700 VAC Fast-Acting

Breaking capacity: 50 kA

Cooper Industries Inc., Bussmann Division,

*

USA

39

4.2 Accuracy

4.2 Accuracy

Accuracy guarantee for

23±5°C(73±9°F), 80%RH or less
temperature and hu­midity
Guaranteed accuracy

1 year
period

Regulated power sup­ply range

3.4 V or lower (until the mark

lights up)

(rdg.: displayed value, dgt.: resolution)

Voltage Measurement

V

Range

[V]

420.0 m

4.200

42.00

420.0
1000

Accuracy

±(rdg.)±(dgt.)

±0.5%±2
±0.5%±2
±0.5%±2
±0.5%±2
±0.5%±2

100 MΩ or more
Approx. 11MΩ
Approx. 10MΩ
Approx. 10MΩ
Approx. 10MΩ

Input Impedance

(Frequency range)

*1

V

420.0 m

4.200

42.00

420.0
1000

±1.5%±3
±1.2%±3
±1.2%±3
±1.2%±3
±1.2%±6

*2

100MΩ or more
Approx. 11MΩ (50 to 500 Hz)
Approx. 10MΩ (50 to 500 Hz)
Approx. 10MΩ (50 to 500 Hz)
Approx. 10MΩ (50 to 500 Hz)

(50 to 100 Hz)

Overload protection (for one minute):
1000 VDC,1000 Vrms(sin)(CAT II),

7

600 VDC,600 Vrms(sin)(CATIII), or 10

V•Hz

*1: For the input of less than 10% of the full scale, ±2 dgt. is

added to the above measurement accuracies.

*2: The above measurement accuracy for the 420.0 mV range

is not defined for inputs of less than 1.0 mV.

4.2 Accuracy

40

(rdg.: displayed value, dgt.: resolution)

Frequency Measurement

Hz

*1

Range

[Hz]

199.99

1999.9

19.999k

199.99k

500.0k

Accuracy

±(rdg.)±(dgt.)

±0.02%±2
±0.02%±1
±0.02%±1
±0.02%±1
±0.02%±1

Input level (Range)

1: 0.8 to 4 V (4.200V)
2: 4 to 40 V (42.00V)
3: 40 to 400 V (420.0V)
4: 400 to 1000 V (1000V)

Overload protection (for one minute):
1000 VDC,1000 Vrms(sin)(CAT II),

7

600 VDC,600 Vrms(sin)(CATI II), or 10

V•Hz

*1: Frequencies of less than 0.50 Hz cannot be measured.

Maximum input voltage: 1000 Vrms(sin) or 10

7

V•Hz

Resistance Measurement/ Continuity Check/
Diode Check

Measurement
current (max.)
(Reference value)

Range

Accuracy

±(rdg.)±(dgt.)

Open terminal

voltage

Ω

(Resis­tance)

(Continu­ity)

420.0Ω

4.200kΩ

42.00kΩ

420.0kΩ

4.200MΩ

42.00MΩ

±0.7%±4
±0.7%±2
±0.7%±2
±0.7%±2
±1.5%±2
±2.5%±2

420.0Ω ± 0.7%± 4 3.4 V or le ss

3.4 V or less
Approx. 0.7V
Approx.0.5V
Approx.0.5V
Approx.0.5V
Approx.0.5V

700μA
250μA
50μA
5μA

0.5μA

0.05μA

Threshold:
50Ω±30Ω

2.00V*1 ±5.0%± 2 3.4 V or less 700 μA

(Diode)

Overload protection (for one minute):
1000 VDC,1000 Vrms(sin)(CAT II),
600 VDC,600 Vrms(sin)(CATI II), or 10

7

V•Hz

*1: The measurement range varies depending on the battery

voltage level.(2.10 V to 2.90 V)

*2: A beeping sound is generated when the continuity is estab-

lished.

41

(rdg.: displayed value, dgt.: resolution)

Current Measurement

4.2 Accuracy

*1

A

A

Range

[A]

42.00μ

420.0μ
4200μ

42.00m

420.0m

10.00*2

42.00μ

420.0μ
4200μ

42.00m

420.0m

10.00*2

Accuracy

±(rdg.)±(dgt.)

±1.5%±4
±1.5%±4
±1.5%±4
±1.5%±4
±1.5%±4
±1.5%±4

±2.5%±5
±2.5%±5
±2.5%±5
±2.5%±5
±2.5%±5
±2.5%±5

Input Impedance

(Shunt resistance)

Approx. 10kΩ
Approx. 100Ω
Approx. 100Ω
Approx. 1Ω
Approx. 1Ω
Approx. 0.01Ω

Approx. 10kΩ
Approx. 100Ω
Approx. 100Ω
Approx. 1Ω
Approx. 1Ω
Approx. 0.01Ω

Frequency ran ge
50 Hz to 500 Hz

Protective Fuse
42μA to 420mA range: 0.5 A/700 VAC,

Breaking capacity 50 kA
10A range: 10A/600VAC, Breaking capacity 10 kA/250 VAC,

200 A/600 VAC
*1:For the input of less than 10% of the full scale, ±2 dgt is

added to the above measurement accuracies.

*2:For the 10-A range, the measurement time is infinite at or

below 7 A and within 1 minute for 7 A to 10 A.

4.2 Accuracy

42

43

5.1 Replacing the Batteries and Fuses

Maintenace and
Service

Chapter 5

5.1 Replacing the Batteries and Fuses

• To avoid electric shock when replacing
the batteries and fuses, first disconnect
the test leads from the object to be mea­sured.

• Before using the product after replacing
the batteries or fuses, replace the cover
and screw.

• Do not mix old and new batteries, or dif­ferent types of batteries. Also, be careful
to observe battery polarity during instal­lation. Otherwise, poor performance or
damage from battery leakage could
result.

• To avoid the possibility of explosion, do
not short circuit, disassemble or inciner­ate batteries.

• Handle and dis po se of ba tteri es in ac c or­dance with local regulations.

• Replace the fuse only with one of the
specified characteristics and voltage and
current ratings. Using a non-specified
fuse or shorting the fuse holder may
cause a life-threatening hazard.

5.1 Replacing the Batteries and Fuses

44

s

r-

e
e

t
e
g

s

e

.
e

o
e

d

er

A fuse is mounted to the μA.mA and A terminals in
order to protect the circuit. If the current cannot be
measured, the fuse may have blown due to
overcurrent. Replace the fuse or battery in
accordance with the procedure specified below.

Lower case

Upper case

Necessary tool: Phillips screwdriv

1. Disconnect the test lead

from the measurement ci
cuit, and make sure th
function selector is in th
OFF position.

2. Position the measuremen

product with the rear cas
(bottom face) pointin
upward, and use the Phillip
screwdriver to remove th
three lock bolts.

3.

Lif t and remove th e rear case

4. Replace the two manganes

batteries (R03) mounted t
the rear case, or the fus
mounted to the front case.

5. Mount the rear case an

tighten the three lock bolts.

μA.mA terminal

10A terminal

Different fuses are mounted to the μA, mA and A
terminals. When replacing a fuse, make sure you
are accessing the correct terminal.

Fuse type
10A terminal:
TDC600-10A (made by Cooper
Bussmann*), F as t-A ctin g, Rating
10A/600VAC, Breaking capacity 10
kA/250 VAC, 200 A/600 VAC

μAmA terminal:
70125 (made by SIBA Inc.), Fast-Act­ing, Rating 0.5 A/700 VAC, Breaking
capacity 50 kA
*Cooper Industries Inc., Bussmann
Division, USA

45

5.2 Cleaning

To clean the product, 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.

5.3 Service

• If the product seems to be malfunctioning, con­firm that the batteries are not discharged, and
that the test leads and fuse are not open cir­cuited before contacting your dealer or Hioki rep­resentative.

5.2 Cleaning

• To avoid corros ion from battery leakage, remove
the batteries from the produc t if it is to be stored
for a long time.

5.3 Service

46

HIOKI 3256-50/51 DIGITAL H iTESTER

Instruction Manual

Publication date: September 2006 Revised edition 4
Edited and p ublished by HIOKI E .E. CORPO RATION

Technical Support Section
All inquiries to International Sales and Marketing De-

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

Printed in Japan 3256C981-04

• 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 headqu arte rs.

• 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]

3256C981-04 06-09H

Printed on recycled paper